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PEP on path module for standard library

P: n/a
Many of you are familiar with Jason Orendorff's path module
<http://www.jorendorff.com/articles/python/path/>, which is frequently
recommended here on c.l.p. I submitted an RFE to add it to the Python
standard library, and Reinhold Birkenfeld started a discussion on it in
python-dev
<http://mail.python.org/pipermail/python-dev/2005-June/054438.html>.

The upshot of the discussion was that many python-dev'ers wanted path
added to the stdlib, but Guido was not convinced and said it must have a
PEP. So Reinhold and I are going to work on one. Reinhold has already
made some changes to the module to fit the python-dev discussion and put
it in CPython CVS at nondist/sandbox/path.

For the PEP, do any of you have arguments for or against including path?
Code samples that are much easier or more difficult with this class
would also be most helpful.

I use path in more of my modules and scripts than any other third-party
module, and I know it will be very helpful when I no longer have to
worry about deploying it.

Thanks in advance,
--
Michael Hoffman
Jul 21 '05 #1
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70 Replies


P: n/a
Michael Hoffman wrote:
For the PEP, do any of you have arguments for or against including path?
Code samples that are much easier or more difficult with this class
would also be most helpful.


I believe the strongest argument for "path" can be made for how it
integrates functionality which, although closely related conceptually,
is currently distributed across a half dozen or more different modules
in the standard library. Especially for newbies (I can only imagine, at
this stage) it would make working with files much easier in a many ways.

"Easier" or "more difficult" is a subjective thing, of course, but one
can't argue with the fact that path can sometimes do through a single
object what would otherwise require several imports and a bunch of calls
into things like open(), os.path, grep, and shutil.

Examples showing effective uses of path that simplify those cases would
probably merit the label "easier" even in Guido's mind, though
unfortunately that's not certain. "Easier" in some minds might simply
translate to "many lines less code", and while path can sometimes do
that, aside from the ease of splitting and joining stuff without
multiple calls to os.path.this-and-that, it really doesn't often reduce
code size _that_ much, in my experience. (Postings to c.l.p showing a
50% reduction in code size for contrived examples notwithstanding.)

A related thoughts: since paths are objects, they have attributes or
properties, and having things like ".basename" and ".parent" readily
available without having to do obscure things like
os.path.split(somepath)[0] makes things much easier to read (therefore
more maintainable). In fact, I'd propose that as another strong
argument in path's favour: it makes code much more readable, even if not
"easier" to write.

Hmm... does "easier" or "more difficult" apply to the writing of the
code or the reading of it? I find it self-evident that code written
using "path" is much easier to read, not necessarily much easier to
write (for non-newbies).

I'd summarize this by saying that the integration of "path" in the
stdlib would make it easier for newbies to write code (that might not be
obvious to a non-newbie... shall we ask some to help?), and easier for
everyone to read code (self-evident, no?), and if that's not a
sufficient condition for inclusion I don't know what is.

-Peter
Jul 21 '05 #2

P: n/a
Peter Hansen wrote:
Michael Hoffman wrote:
For the PEP, do any of you have arguments for or against including path?
Code samples that are much easier or more difficult with this class
would also be most helpful.


I believe the strongest argument for "path" can be made for how it
integrates functionality which, although closely related conceptually,
is currently distributed across a half dozen or more different modules
in the standard library. Especially for newbies (I can only imagine, at
this stage) it would make working with files much easier in a many ways.


+10

One of the few things that annoys me about the stdlib is what one could call
performing 'shell-scripting-like' tasks, and precisely because of the problem
you point out. A number of conceptually related and common tasks are
scattered all over, and every time I need to write this kind of code, I find
myself paging over the docs for multiple modules, with no real intuition as to
where I could even guess where to find things. This is very unusual for
python, where in most cases things are so well organized, that blind guessing
tends to work remarkably well.

Personally I like the path module _a lot_, though I'm sure a thorough once-over
from c.l.py and python-dev, via a PEP, can only make it better and smooth out
hidden rough edges and corner cases. But I'll be very happy if it does go
into the stdlib in the future.

Just my .02.

Best,

f

Jul 21 '05 #3

P: n/a
I really love Jason's 'path' module. Sadly, I've encountered a serious
problem with using it. When you try to 'freeze' an application module,
and Jason's 'path' module is present in any of the directories that are
looked at by freeze's module finder (your app doesn't have to import
it), freeze goes into an infinite loop of imports, eventually getting a
'maximum recursion depth' exception. This seems to be related to
freeze getting confused between 'os.path' and Jason's 'path'.

I encountered this using Jason's latest 'path' module and Python 2.3.2.
I was able to solve it for my use by renaming path.py to newpath.py
and using 'from newpath import path' in my modules.

I've just notified Jason about this. I presume a solution like mine
will be used, and look forward to seeing Jason's module in stdlib.

Jul 21 '05 #4

P: n/a
FYI: I modified the path module a bit so that it fits many of the suggestions
from python-dev, and put the result in the Python CVS tree under
nondist/sandbox/path.

Most prominent change is that it doesn't inherit from str/unicode anymore.
I found this distinction important, because as a str subclass the Path object
has many methods that don't make sense for it.

Peter Hansen wrote:
Michael Hoffman wrote:
For the PEP, do any of you have arguments for or against including path?
Code samples that are much easier or more difficult with this class
would also be most helpful.
I believe the strongest argument for "path" can be made for how it
integrates functionality which, although closely related conceptually,
is currently distributed across a half dozen or more different modules
in the standard library. Especially for newbies (I can only imagine, at
this stage) it would make working with files much easier in a many ways.

"Easier" or "more difficult" is a subjective thing, of course, but one
can't argue with the fact that path can sometimes do through a single
object what would otherwise require several imports and a bunch of calls
into things like open(), os.path, grep, and shutil.


Correct.
Examples showing effective uses of path that simplify those cases would
probably merit the label "easier" even in Guido's mind, though
unfortunately that's not certain. "Easier" in some minds might simply
translate to "many lines less code", and while path can sometimes do
that, aside from the ease of splitting and joining stuff without
multiple calls to os.path.this-and-that, it really doesn't often reduce
code size _that_ much, in my experience. (Postings to c.l.p showing a
50% reduction in code size for contrived examples notwithstanding.)
Well, these examples are the ones we'd like to see here. So, people:
If you posted examples to c.l.py in the past, please try to collect
them here!
A related thoughts: since paths are objects, they have attributes or
properties, and having things like ".basename" and ".parent" readily
available without having to do obscure things like
os.path.split(somepath)[0] makes things much easier to read (therefore
more maintainable). In fact, I'd propose that as another strong
argument in path's favour: it makes code much more readable, even if not
"easier" to write.

Hmm... does "easier" or "more difficult" apply to the writing of the
code or the reading of it? I find it self-evident that code written
using "path" is much easier to read, not necessarily much easier to
write (for non-newbies).
And it is much more "Pythonic" in my eyes. Though that word may be inaccurate
when it comes from someone else that Guido, I feel that endless chains of
'[os.path.join(os.path.join(z, "a"), x) for x in os.path.listdir(os.path.join(z, "a") if os.path.isfile(os.path.join(....
are not qualified as being Pythonic.
I'd summarize this by saying that the integration of "path" in the
stdlib would make it easier for newbies to write code (that might not be
obvious to a non-newbie... shall we ask some to help?), and easier for
everyone to read code (self-evident, no?), and if that's not a
sufficient condition for inclusion I don't know what is.


Reinhold
Jul 21 '05 #5

P: n/a

"Reinhold Birkenfeld" <re************************@wolke7.net> wrote in
message news:3k************@individual.net...
Most prominent change is that it doesn't inherit from str/unicode
anymore.
I found this distinction important, because as a str subclass the Path
object
has many methods that don't make sense for it.


While I am - on adding more to learn, I am + on collecting scattered
filesystem functions into methods of coherent classes for eventually
replacement of the former. And I understand that this will mean a period
of duplication. But it is important to get the replacement right.

My only knowledge of the path module is what has been posted. However, it
seems to me that a path is conceptually a sequence of strings, rather than
the single joined-string representation thereof. If so, then of course it
is not and should not be a subclass of single strings. But that Path was
so defined makes me wonder, in my ignorance, whether the current
implementation is the best we can do for the future.

One advantage, for instance, of a split-up list implementation is that a
set of paths with a common prefix could be represented by replacing the
last string with a set of strings.

A more OO-friendly OS than the dominant ones today would accept a path as a
list (sequence) instead of requiring that the list be joined (by an
artifactual character) just to be split back into a list again.

My thoughts anyway.

Terry J. Reedy

Jul 21 '05 #6

P: n/a
mk***@webmd.net wrote:
I really love Jason's 'path' module. Sadly, I've encountered a serious
problem with using it. When you try to 'freeze' an application module,
and Jason's 'path' module is present in any of the directories that are
looked at by freeze's module finder (your app doesn't have to import
it), freeze goes into an infinite loop of imports, eventually getting a
'maximum recursion depth' exception. This seems to be related to
freeze getting confused between 'os.path' and Jason's 'path'.

I encountered this using Jason's latest 'path' module and Python 2.3.2.
I was able to solve it for my use by renaming path.py to newpath.py
and using 'from newpath import path' in my modules.

I've just notified Jason about this. I presume a solution like mine
will be used, and look forward to seeing Jason's module in stdlib.


This sounds like a bug in "freeze" rather than something that should be
worked around in the standard library. Although there have already been
people opposed to naming it path because the duplication with os.path
might confuse humans.
--
Michael Hoffman
Jul 21 '05 #7

P: n/a
Reinhold Birkenfeld wrote:
FYI: I modified the path module a bit so that it fits many of the suggestions
from python-dev, and put the result in the Python CVS tree under
nondist/sandbox/path.

Most prominent change is that it doesn't inherit from str/unicode anymore.
I found this distinction important, because as a str subclass the Path object
has many methods that don't make sense for it.


Having path descend from str/unicode is extremely useful since I can
then pass a path object to any function someone else wrote without
having to worry about whether they were checking for basestring. I think
there is a widely used pattern of accepting either a basestring[1] or a
file-like object as a function argument, and using isinstance() to
figure out which it is.

What do you gain from removing these methods? A smaller dir()?

[1] Probably str in actuality.
--
Michael Hoffman
Jul 21 '05 #8

P: n/a
Michael Hoffman wrote:
Reinhold Birkenfeld wrote:
FYI: I modified the path module a bit so that it fits many of the suggestions
from python-dev, and put the result in the Python CVS tree under
nondist/sandbox/path.

Most prominent change is that it doesn't inherit from str/unicode anymore.
I found this distinction important, because as a str subclass the Path object
has many methods that don't make sense for it.
Having path descend from str/unicode is extremely useful since I can
then pass a path object to any function someone else wrote without
having to worry about whether they were checking for basestring. I think
there is a widely used pattern of accepting either a basestring[1] or a
file-like object as a function argument, and using isinstance() to
figure out which it is.


Where do you see that pattern? IIRC it's not in the stdlib.
What do you gain from removing these methods? A smaller dir()?


It made sense to me at the time I changed this, although at the moment
I can't exactly recall the reasons.

Probably as Terry said: a path is both a list and a string.

Reinhold
Jul 21 '05 #9

P: n/a
Michael Hoffman wrote:
mk***@webmd.net wrote:
I really love Jason's 'path' module. Sadly, I've encountered a serious
problem with using it. When you try to 'freeze' an application module,
and Jason's 'path' module is present in any of the directories that are
looked at by freeze's module finder (your app doesn't have to import
it), freeze goes into an infinite loop of imports, eventually getting a
'maximum recursion depth' exception. This seems to be related to
freeze getting confused between 'os.path' and Jason's 'path'.

I encountered this using Jason's latest 'path' module and Python 2.3.2.
I was able to solve it for my use by renaming path.py to newpath.py
and using 'from newpath import path' in my modules.

I've just notified Jason about this. I presume a solution like mine
will be used, and look forward to seeing Jason's module in stdlib.


This sounds like a bug in "freeze" rather than something that should be
worked around in the standard library. Although there have already been
people opposed to naming it path because the duplication with os.path
might confuse humans.


As the most likely placement will be a class named "Path" inside the "os.path"
module, that bug with freeze won't apply to the "stdlib version" of Path.

Reinhold
Jul 21 '05 #10

P: n/a
"Michael Hoffman" <ca*******@mh391.invalid> wrote in message
news:db**********@gemini.csx.cam.ac.uk...
Many of you are familiar with Jason Orendorff's path module
<http://www.jorendorff.com/articles/python/path/>, which is frequently
recommended here on c.l.p. I submitted an RFE to add it to the Python
standard library, and Reinhold Birkenfeld started a discussion on it in
python-dev
<http://mail.python.org/pipermail/python-dev/2005-June/054438.html>.

The upshot of the discussion was that many python-dev'ers wanted path
added to the stdlib, but Guido was not convinced and said it must have a
PEP.
Why did Guido want a PEP? Is it because he likes the idea but
feels the feature set needs to be examined a bit more by the wider
community, or is it some other reason?

I'm all in favor of having something that gives an alternative to
the kludge of functions that are "just a thin wrapper on the C
standard library." Considering the known problems with the
C standard library and the fact that it's strictly procedural, that
statement doesn't fill me with confidence. Rather it creates a
mild sense of dread: nobody has thought out how to do those
functions in a useful oo manner.

Path looks useable to me. Do I think it's going to be the
last word? I sincerely hope not! The only way we're going
to find out where it really needs to go from here, though, is
to put it out and find out how the wider community uses
and abuses it.

John Roth
Thanks in advance,
--
Michael Hoffman


Jul 21 '05 #11

P: n/a
John Roth wrote:
"Michael Hoffman" <ca*******@mh391.invalid> wrote in message
news:db**********@gemini.csx.cam.ac.uk...
Many of you are familiar with Jason Orendorff's path module
<http://www.jorendorff.com/articles/python/path/>, which is frequently
recommended here on c.l.p. I submitted an RFE to add it to the Python
standard library, and Reinhold Birkenfeld started a discussion on it in
python-dev
<http://mail.python.org/pipermail/python-dev/2005-June/054438.html>.

The upshot of the discussion was that many python-dev'ers wanted path
added to the stdlib, but Guido was not convinced and said it must have a
PEP.


Why did Guido want a PEP? Is it because he likes the idea but
feels the feature set needs to be examined a bit more by the wider
community, or is it some other reason?


He said,

"""
Whoa! Do we really need a completely different mechanism for doing the
same stuff we can already do? The path module seems mostly useful for
folks coming from Java who are used to the Java Path class. With the
massive duplication of functionality we should also consider what to
recommend for the future: will the old os.path module be deprecated,
or are we going to maintain both alternatives forever? (And what about
all the duplication with the os module itself, like the cwd()
constructor?) Remember TOOWTDI.
"""

Reinhold
Jul 21 '05 #12

P: n/a
Reinhold Birkenfeld wrote:
Michael Hoffman wrote:
Having path descend from str/unicode is extremely useful since I can
then pass a path object to any function someone else wrote without
having to worry about whether they were checking for basestring. I think
there is a widely used pattern of accepting either a basestring[1] or a
file-like object as a function argument, and using isinstance() to
figure out which it is.


Where do you see that pattern? IIRC it's not in the stdlib.


I do not think it is a *good* pattern, but it is used in Biopython. Of
course, there they ARE using things like type("") so on a unicode
filesystem it would already break. I seem to recall seeing it elsewhere,
but I can't remember where.

If you remove the basestring superclass, then you remove the ability to
use path objects as a drop-in replacement for any path string right now.
You will either have to use str(pathobj) or carefully check that the
function/framework you are passing the path to does not use isinstance()
or any of the string methods that are now gone.
What do you gain from removing these methods? A smaller dir()?


It made sense to me at the time I changed this, although at the moment
I can't exactly recall the reasons.

Probably as Terry said: a path is both a list and a string.


I can see the case for thinking of it in both of those ways. In the end
a path is a sequence object. But a sequence of what?

I have a path that looks like this:

r"c:\windows\system32:altstream\test.dir\myfile.tx t.zip:altstream"

One way to divide this is solely based on path separators:

['c:', 'windows', 'system32:altstream', 'test.dir',
'myfile.txt.zip:altstream']

But then some of the elements of this sequence have more meaning than
just being strings. "c:" is certainly something different from
"windows." The file name and alternate data stream name of each element
could be represented as a tuple.

The extensions can also be dealt with as a sequence. I have dealt with
things like filename = "filename.x.y.z" and wanted to get "filename.x"
before. The current stdlib solution,
os.path.splitext(os.path.splitext(filename)[0])[0] is extremely clunky,
and I have long desired something better. (OK, using
filename.split(os.extsep) works a little better, but you get the idea.)

So if you start breaking the path into a sequence of bigger items than
single character, where does it stop? What is a good design for this?
--
Michael Hoffman
Jul 21 '05 #13

P: n/a
Reinhold Birkenfeld wrote:
John Roth wrote:
Why did Guido want a PEP?


He said,

"""
Whoa! Do we really need a completely different mechanism for doing the
same stuff we can already do? The path module seems mostly useful for
folks coming from Java who are used to the Java Path class.
"""


What is this Java Path class? I have been STFWing and have found nothing
on it in the. Indeed if you search for "Java Path class" (with quotes)
almost half of the pages are this message from Guido. ;)

Any Java hackers here want to tell us of the wonders of the Java Path
class? I would be interested in seeing how other OO languages deal with
paths.
--
Michael Hoffman
Jul 21 '05 #14

P: n/a
"Reinhold Birkenfeld" <re************************@wolke7.net> wrote in
message news:3k************@individual.net...
John Roth wrote:
"Michael Hoffman" <ca*******@mh391.invalid> wrote in message
news:db**********@gemini.csx.cam.ac.uk...
Many of you are familiar with Jason Orendorff's path module
<http://www.jorendorff.com/articles/python/path/>, which is frequently
recommended here on c.l.p. I submitted an RFE to add it to the Python
standard library, and Reinhold Birkenfeld started a discussion on it in
python-dev
<http://mail.python.org/pipermail/python-dev/2005-June/054438.html>.

The upshot of the discussion was that many python-dev'ers wanted path
added to the stdlib, but Guido was not convinced and said it must have a
PEP.
Why did Guido want a PEP? Is it because he likes the idea but
feels the feature set needs to be examined a bit more by the wider
community, or is it some other reason?


He said,

"""
Whoa! Do we really need a completely different mechanism for doing the
same stuff we can already do? The path module seems mostly useful for
folks coming from Java who are used to the Java Path class. With the
massive duplication of functionality we should also consider what to
recommend for the future: will the old os.path module be deprecated,
or are we going to maintain both alternatives forever? (And what about
all the duplication with the os module itself, like the cwd()
constructor?) Remember TOOWTDI.
"""


Read literally, this says (at least to me) "I don't want to fix it because
I don't think it's broke."

As far as the Java remark is concerned, I suspect that it's because
in Java there is no such thing as a function; everything is either a
method on an object or a static method on a class.

And as far as I'm concerned, it's broke. I could see getting rid of the
bits and pieces of procedural code in 3.0, but not sooner.

John Roth
Reinhold


Jul 22 '05 #15

P: n/a
"Reinhold Birkenfeld" <re************************@wolke7.net> wrote:
Why did Guido want a PEP? Is it because he likes the idea but
feels the feature set needs to be examined a bit more by the wider
community, or is it some other reason?


He said,

"""
Whoa! Do we really need a completely different mechanism for doing the
same stuff we can already do? The path module seems mostly useful for
folks coming from Java who are used to the Java Path class. With the
massive duplication of functionality we should also consider what to
recommend for the future: will the old os.path module be deprecated,
or are we going to maintain both alternatives forever? (And what about
all the duplication with the os module itself, like the cwd()
constructor?) Remember TOOWTDI.
"""


Duplication is a valid point for debate, so the PEP should definitely address it. IMO os.path and
most (if not all) other equivalent modules and functions should be deprecated, though still working
until 2.9 for backwards compatibility, and dropped for python 3K.

George
Jul 22 '05 #16

P: n/a
"John Roth" <ne********@jhrothjr.com> wrote:
"Reinhold Birkenfeld" <re************************@wolke7.net> wrote
He said,

"""
Whoa! Do we really need a completely different mechanism for doing the
same stuff we can already do? The path module seems mostly useful for
folks coming from Java who are used to the Java Path class. With the
massive duplication of functionality we should also consider what to
recommend for the future: will the old os.path module be deprecated,
or are we going to maintain both alternatives forever? (And what about
all the duplication with the os module itself, like the cwd()
constructor?) Remember TOOWTDI.
"""


Read literally, this says (at least to me) "I don't want to fix it because
I don't think it's broke."


Or rather "I prefer a single existing mediocre solution than two solutions (even if the second was
better)".

George
Jul 22 '05 #17

P: n/a
Reinhold Birkenfeld:
And it is much more "Pythonic" in my eyes. Though that word may be inaccurate
when it comes from someone else that Guido, I feel that endless chains of
'[os.path.join(os.path.join(z, "a"), x) for x in os.path.listdir(os.path.join(z, "a") if os.path.isfile(os.path.join(....
are not qualified as being Pythonic.


I like Path but the above is trying too hard to be poor code.
os.path.join takes more than 2 arguments, so that should be
[os.path.join(z, "a", x) for x in os.path.listdir(os.path.join(z, "a")
if os.path.isfile(os.path.join(....

Neil
Jul 22 '05 #18

P: n/a
Michael Hoffman wrote:
Having path descend from str/unicode is extremely useful since I can
then pass a path object to any function someone else wrote without
having to worry about whether they were checking for basestring. I think
there is a widely used pattern of accepting either a basestring[1] or a
file-like object as a function argument, and using isinstance() to
figure out which it is.
Reinhold Birkenfeld wrote: Where do you see that pattern? IIRC it's not in the stdlib.


Here's the first place that comes to mind for me

xml.sax.saxutils

def prepare_input_source(source, base = ""):
"""This function takes an InputSource and an optional base URL and
returns a fully resolved InputSource object ready for reading."""

if type(source) in _StringTypes:
source = xmlreader.InputSource(source)
elif hasattr(source, "read"):
f = source
source = xmlreader.InputSource()
source.setByteStream(f)
if hasattr(f, "name"):
source.setSystemId(f.name)
and xml.dom.pulldom

def parse(stream_or_string, parser=None, bufsize=None):
if bufsize is None:
bufsize = default_bufsize
if type(stream_or_string) in _StringTypes:
stream = open(stream_or_string)
else:
stream = stream_or_string
if not parser:
parser = xml.sax.make_parser()
return DOMEventStream(stream, parser, bufsize)

Using the power of grep

aifc.py
def __init__(self, f):
if type(f) == type(''):
f = __builtin__.open(f, 'rb')
# else, assume it is an open file object already
self.initfp(f)

binhex.py
class HexBin:
def __init__(self, ifp):
if type(ifp) == type(''):
ifp = open(ifp)

imghdr.py
if type(file) == type(''):
f = open(file, 'rb')
h = f.read(32)
else:
location = file.tell()
h = file.read(32)
file.seek(location)
f = None

mimify.py
if type(infile) == type(''):
ifile = open(infile)
if type(outfile) == type('') and infile == outfile:
import os
d, f = os.path.split(infile)
os.rename(infile, os.path.join(d, ',' + f))
else:
ifile = infile

wave.py
def __init__(self, f):
self._i_opened_the_file = None
if type(f) == type(''):
f = __builtin__.open(f, 'rb')
self._i_opened_the_file = f
# else, assume it is an open file object already
self.initfp(f)
compiler/transformer.py:

if type(file) == type(''):
file = open(file)
return self.parsesuite(file.read())

plat-mac/applesingle.py
if type(input) == type(''):
input = open(input, 'rb')
# Should we also test for FSSpecs or FSRefs?
header = input.read(AS_HEADER_LENGTH)

site-packages/ZODB/ExportImport.py
if file is None: file=TemporaryFile()
elif type(file) is StringType: file=open(file,'w+b')
site-packages/numarray/ndarray.py
if type(file) == type(""):
name = 1
file = open(file, 'wb')
site-packages/kiva/imaging/GdImageFile.py
if type(fp) == type(""):
import __builtin__
filename = fp
fp = __builtin__.open(fp, "rb")
else:
filename = ""

site-packages/reportlab/graphics/renderPM.py
if type(image.path) is type(''):
im = _getImage().open(image.path).convert('RGB')
else:
im = image.path.convert('RGB')
site-packages/twisted/protocols/irc.py
def __init__(self, file):
if type(file) is types.StringType:
self.file = open(file, 'r')

(hmm, that last one looks buggy. It should
have a "else: self.file = file" afterwards.)
Used in the std. lib and used by many different
people. (I excluded the Biopython libraries
in this list, btw, because I may have influenced
the use of this sort of type check.)

Andrew
da***@dalkescientific.com

Jul 22 '05 #19

P: n/a
on 22.07.2005 00:21 Michael Hoffman said the following:
Reinhold Birkenfeld wrote:
John Roth wrote:

Why did Guido want a PEP?


He said,

"""
Whoa! Do we really need a completely different mechanism for doing the
same stuff we can already do? The path module seems mostly useful for
folks coming from Java who are used to the Java Path class.
> """


What is this Java Path class? I have been STFWing and have found nothing
on it in the. Indeed if you search for "Java Path class" (with quotes)
almost half of the pages are this message from Guido. ;)

Any Java hackers here want to tell us of the wonders of the Java Path
class?


no such thing exists.

there is only the `File` class that incorporates a little bit of the
`path` functionality and some of the python built-in `file` functionality.

my little self would actually propose to make *path* a built-in type as
an intermediate between file and basestring/str/unicode (the latter is
probably needed).

*ducks*

Jul 22 '05 #20

P: n/a
Stefan Rank wrote:
on 22.07.2005 00:21 Michael Hoffman said the following:
Any Java hackers here want to tell us of the wonders of the Java Path
class?


no such thing exists.

there is only the `File` class that incorporates a little bit of the
`path` functionality and some of the python built-in `file` functionality.


Ah, here it is:

http://java.sun.com/j2se/1.5.0/docs/...a/io/File.html
--
Michael Hoffman
Jul 22 '05 #21

P: n/a
George Sakkis wrote:
Read literally, this says (at least to me) "I don't want to fix it
because I don't think it's broke."


Or rather "I prefer a single existing mediocre solution than two
solutions (even if the second was better)".

Except that he is open to persuasion, so the PEP has to demonstrate that
the duplication is worth the benefit.

Personally I think the concept of a specific path type is a good one, but
subclassing string just cries out to me as the wrong thing to do. In other
words, to me a path represents something in a filesystem, the fact that it
has one, or indeed several string representations does not mean that the
path itself is simply a more specific type of string.

You should need an explicit call to convert a path to a string and that
forces you when passing the path to something that requires a string to
think whether you wanted the string relative, absolute, UNC, uri etc.

It may even be that we need a hierarchy of path classes: URLs need similar
but not identical manipulations to file paths, so if we want to address the
failings of os.path perhaps we should also look at the failings of urlparse
at the same time.
Jul 22 '05 #22

P: n/a
Duncan Booth wrote:
You should need an explicit call to convert a path to a string and that
forces you when passing the path to something that requires a string to
think whether you wanted the string relative, absolute, UNC, uri etc.


Egad. I'm not sure if that will really make people's lives easier.
--
Michael Hoffman
Jul 22 '05 #23

P: n/a
mk***@webmd.net writes:
I really love Jason's 'path' module. Sadly, I've encountered a serious
problem with using it. When you try to 'freeze' an application module,
and Jason's 'path' module is present in any of the directories that are
looked at by freeze's module finder (your app doesn't have to import
it), freeze goes into an infinite loop of imports, eventually getting a
'maximum recursion depth' exception. This seems to be related to
freeze getting confused between 'os.path' and Jason's 'path'.

I encountered this using Jason's latest 'path' module and Python 2.3.2.
I was able to solve it for my use by renaming path.py to newpath.py
and using 'from newpath import path' in my modules.

I've just notified Jason about this. I presume a solution like mine
will be used, and look forward to seeing Jason's module in stdlib.


That was a bug in modulefinder, which was fixed in Python 2.4 and 2.3.4.
See http://www.python.org/sf/876278.

Thomas
Jul 22 '05 #24

P: n/a
> When you try to 'freeze' an application module,
and Jason's 'path' module is present in any of the directories that are
looked at by freeze's module finder (your app doesn't have to import
it), freeze goes into an infinite loop of imports, eventually getting a
'maximum recursion depth' exception. This seems to be related to
freeze getting confused between 'os.path' and Jason's 'path'.


This is a bug in distutils. Thomas Hellers py2exe encounters the same
bug. As much as I remember our conversation, he submitted a patch to
distutils.

In the meanwhile I renamed path.py to jpath.py, usings Jason's first
letter in a motion of honour while circumventing this bug.

Harald

Jul 22 '05 #25

P: n/a
>Having path descend from str/unicode is extremely useful since I can
then pass a path object to any function someone else wrote without
having to worry about whether they were checking for basestring.

I use path.py from Jason to encapsulate a lot of the windows plattform
specialities of path dealing.
Being able to use path-opjects at every place where I would use str or
unicode is very essential, because I often use Python to tame Excel and
Word. To open files within these programms needs some "plain str" as
"PATH" for the file. (which, of course, can also be down by ways to
"convert" PATH to STRING.

Harald

Jul 22 '05 #26

P: n/a
Reinhold Birkenfeld wrote:
Michael Hoffman wrote:
What do you gain from removing these methods? A smaller dir()?


It made sense to me at the time I changed this, although at the moment
I can't exactly recall the reasons.


Along with some of the others (and as a fairly heavy user of "path"), I
would caution strongly against jumping to do make this change.

Given that a strong part of the justification for path's inclusion in
the standard library (as expressed here in the past) is that it is
stable and widely used, making such a fundamental change at this late
stage just prior to its possible acceptance seems to me very risky.

I have noticed in a number of cases where a "path" was usable as a
drop-in replacement for strings that previously contained paths. I
can't say for sure, but I strongly suspect some of that could would be
broken if "paths" weren't basestrings. I'll attempt to check in my own
code.

Even if those uses don't actually break, it can *also* be useful to have
the string methods available on a path object, so I'm also uncertain
what you gain by removing that connection, though it's clear what things
you might be losing.

-2 for this idea.

-Peter
Jul 22 '05 #27

P: n/a
Duncan Booth wrote:
Personally I think the concept of a specific path type is a good one, but
subclassing string just cries out to me as the wrong thing to do. In other
words, to me a path represents something in a filesystem, the fact that it
has one, or indeed several string representations does not mean that the
path itself is simply a more specific type of string.

You should need an explicit call to convert a path to a string and that
forces you when passing the path to something that requires a string to
think whether you wanted the string relative, absolute, UNC, uri etc.


Duncan, are you another formerly non-user of path who has this opinion,
or have you already attempted to use path extensively in your code?

I'm not saying I dismiss the opinions of those who haven't actually
tried working with a string-based path object, but it's worth
considering that you might adopt a different opinion after using it for
a while.

I did.

-Peter
Jul 22 '05 #28

P: n/a
"Duncan Booth" <du**********@invalid.invalid> wrote:
Personally I think the concept of a specific path type is a good one, but
subclassing string just cries out to me as the wrong thing to do. In other
words, to me a path represents something in a filesystem, the fact that it
has one, or indeed several string representations does not mean that the
path itself is simply a more specific type of string.

You should need an explicit call to convert a path to a string and that
forces you when passing the path to something that requires a string to
think whether you wanted the string relative, absolute, UNC, uri etc.


First off, I find this is a relatively small detail overall, that is,
regardless of whether path subclasses string or not, its addition in
the standard library will be a step forward. Havind said that, I think
the choice between subclassing or not is going to be a
practicality-vs-purity decision. You're right, conceptually a path
HAS_A string description, not IS_A string, so from a pure OO point of
view, it should not inherit string. OTOH, people in favor of the
subclassing point out the convenience for many (or most) common cases.
It's a tradeoff, so arguments for both cases should be discussed.

George

Jul 22 '05 #29

P: n/a

"Duncan Booth" <du**********@invalid.invalid> wrote in message
news:Xn*************************@127.0.0.1...
George Sakkis wrote:
You should need an explicit call to convert a path to a string and that
forces you when passing the path to something that requires a string to
think whether you wanted the string relative, absolute, UNC, uri etc.

It may even be that we need a hierarchy of path classes: URLs need similar
but not identical manipulations to file paths, so if we want to address
the
failings of os.path perhaps we should also look at the failings of
urlparse
at the same time.


You have to start somewhere. One of the lessons that's beginning
to seep into people's minds is that getting something that works
out there is almost always preferable to (over) design by committee.

How to do a comprehensive, covers all the corner cases file
system object (or object hierarchy, etc) has been discussed before,
and nothing has ever come of it. Starting with an object that
actually does something some people want gives the designers a
chance to look at things in the wild.

John Roth

Jul 22 '05 #30

P: n/a
on 22.07.2005 16:14 George Sakkis said the following:
"Duncan Booth" <du**********@invalid.invalid> wrote:
Personally I think the concept of a specific path type is a good one, but
subclassing string just cries out to me as the wrong thing to do. In other
words, to me a path represents something in a filesystem, the fact that it
has one, or indeed several string representations does not mean that the
path itself is simply a more specific type of string.
[snip] practicality-vs-purity decision. You're right, conceptually a path
HAS_A string description, not IS_A string, so from a pure OO point of
view, it should not inherit string.


Java has `File` which mixes the concepts "an object in the filesystem"
and "a structured locator for such objects (in a hierarchical fs) that
might or might not correspond to an object that is actually there".

`file` and `path` separate that. I think this is very reasonable.

(It would be nice to get `path`(s) easily from a `file`, at the moment
there is only file.name if I'm not mistaken).

And a `path`, to me, actually IS_A string (unicode string) that happens
to have special behaviour (such as os dependent quirks like a
pathseparator that automatically get translated, comparable to '\n' used
internally in strings translated to '\n'|'\r\n')

stefan

Jul 22 '05 #31

P: n/a
George Sakkis wrote:
Havind said that, I think
the choice between subclassing or not is going to be a
practicality-vs-purity decision. You're right, conceptually a path
HAS_A string description, not IS_A string, so from a pure OO point of
view, it should not inherit string. OTOH, people in favor of the
subclassing point out the convenience for many (or most) common cases.


It would be an entirely different matter if we were designing a language
from scratch. But we have to deal with an existing codebase that expects
strings.

Here's some code I just wrote seconds ago to construct a path for a scp
upload:

"""
DST_DIRPATH = path("host:~/destination")
RSS_EXT = "rss"

dst_filenamebase = os.extsep.join([postcode.lower(), RSS_EXT])
dst_filepath = DST_DIRPATH.joinpath(dst_filenamebase)
"""

With the current path implementation, this Just Works. If I were using
something that parsed and understood paths, the scp/rcp convention of
host:filename would either cause an error or have to be programmed in
separately. The current implementation is much more flexible.

What are the practical advantages and conveniences of *not* subclassing
from basestring?
--
Michael Hoffman
Jul 22 '05 #32

P: n/a
"Duncan Booth" <du**********@invalid.invalid> wrote:
Personally I think the concept of a specific path type is a good one, but
subclassing string just cries out to me as the wrong thing to do. In other
words, to me a path represents something in a filesystem, the fact that it
has one, or indeed several string representations does not mean that the
path itself is simply a more specific type of string.

You should need an explicit call to convert a path to a string and that
forces you when passing the path to something that requires a string to
think whether you wanted the string relative, absolute, UNC, uri etc.


First off, I find this is a relatively small detail overall, that is, regardless of whether path
subclasses string or not, its addition in the standard library will be a step forward. Havind said
that, I think the choice between subclassing or not is going to be a practicality-vs-purity
decision. You're right, conceptually a path HAS_A string description, not IS_A string, so from a
pure OO point of view, it should not inherit string. OTOH, people in favor of the subclassing point
out the convenience for many (or most) common cases. It's a tradeoff, so arguments for both cases
should be discussed.

George


Jul 22 '05 #33

P: n/a
Peter Hansen wrote:
Duncan, are you another formerly non-user of path who has this opinion,
or have you already attempted to use path extensively in your code?
I'm a currently non-user of path who would probably use it if it were in
the standard library but so far have been satisfied to use os.path.
I'm not saying I dismiss the opinions of those who haven't actually
tried working with a string-based path object, but it's worth
considering that you might adopt a different opinion after using it for
a while.
I fully accept that. My point is simply that as a non-user, it sounds to me
as though subclassing string is the wrong approach. I would have expected a
path object to be a sequence of path elements rather than a sequence of
characters. This is basically just a gut feeling though, so I'm perfectly
happy to be told that I'm wrong.

BTW, does it matter at all in practical use that the base class of path
varies between str and unicode depending on the platform?

John Roth wrote: You have to start somewhere. One of the lessons that's beginning
to seep into people's minds is that getting something that works
out there is almost always preferable to (over) design by committee.


Dead right, but once it goes into the standard library it has to pretty
well stop evolving, so it needs to be right, or as close as possible before
that happens.

Jul 22 '05 #34

P: n/a
Duncan Booth wrote:
I would have expected a
path object to be a sequence of path elements rather than a sequence of
characters.


Maybe it's nitpicking, but I don't think that a path object should be a
'sequence of path elements' in an iterator context.

This means that

for element in pathobject:

has no intuitive meaning for me, so it shouldn't be allowed.

Daniel
Jul 22 '05 #35

P: n/a
"Duncan Booth" <du**********@invalid.invalid> wrote in message
news:Xn*************************@127.0.0.1...

John Roth wrote:
You have to start somewhere. One of the lessons that's beginning
to seep into people's minds is that getting something that works
out there is almost always preferable to (over) design by committee.
Dead right, but once it goes into the standard library it has to pretty
well stop evolving, so it needs to be right, or as close as possible
before
that happens.


It has to stop evolving in incompatible directions, at least. Although
there is a precident with the process functions, classes, module,
whatever it is. It's up to five versions now, isn't it?

AFAICT, from a very broad brush perspective, there is really
only one substantive issue: how to handle multiple path-like
"things". URLs have been mentioned in this thread, different
file systems and a possible in-memory file system have been
mentioned in other threads.

So whatever gets out there first shouldn't preempt the ability
to eventually fit into a wider structure without substantial
and incompatible modifications.

John Roth


Jul 22 '05 #36

P: n/a
"Daniel Dittmar" <da************@sap.corp> wrote in message
news:db**********@news.sap-ag.de...
Duncan Booth wrote:
I would have expected a path object to be a sequence of path elements
rather than a sequence of characters.
Maybe it's nitpicking, but I don't think that a path object should be a
'sequence of path elements' in an iterator context.

This means that

for element in pathobject:

has no intuitive meaning for me, so it shouldn't be allowed.


However, a path as a sequence of characters has even less
meaning - I can't think of a use, while I have an application
where traversing a path as a sequence of path elements makes
perfect sense: I need to descend the directory structure, directory
by directory, looking for specific files and types.

John Roth
Daniel


Jul 22 '05 #37

P: n/a
Michael Hoffman wrote:
Here's some code I just wrote seconds ago to construct a path for a
scp upload:

"""
DST_DIRPATH = path("host:~/destination")
RSS_EXT = "rss"

dst_filenamebase = os.extsep.join([postcode.lower(), RSS_EXT])
dst_filepath = DST_DIRPATH.joinpath(dst_filenamebase)
"""

With the current path implementation, this Just Works.
It isn't at all obvious to me that it works:
import os
from path import path
postcode = "AA2 9ZZ"
DST_DIRPATH = path("host:~/destination")
RSS_EXT = "rss"

dst_filenamebase = os.extsep.join([postcode.lower(), RSS_EXT])
dst_filepath = DST_DIRPATH.joinpath(dst_filenamebase)
print dst_filepath host:~/destination\aa2 9zz.rss

If I were using
something that parsed and understood paths, the scp/rcp convention of
host:filename would either cause an error or have to be programmed in
separately. The current implementation is much more flexible.
You still have to program your scp path separately from your filesystem
path in order to handle the different conventions for path separator
characters and maybe also escaping special characters in the path (I don't
use scp much so I don't know if this is required).
What are the practical advantages and conveniences of *not*
subclassing from basestring?


Simplification of the api: not having methods such as center, expandtabs
and zfill.

Not having the base class change from str to unicode depending on which
system you run your code?

Fewer undetected bugs (explicit is better than implicit)?

Perhaps none of these matter in practice. As I said elsewhere I haven't
used path for anything real, so I'm still finding surprises such as why
this doesn't do what I expect:
p = path('a/b')
q = path('c/d')
p+q

path(u'a/bc/d')

If path didn't subclass string then either this would have been
implemented, and probably would Do The Right Thing, or it wouldn't be
implemented so I'd quickly realise I needed to do something else. Instead
it does something suprising.
Jul 22 '05 #38

P: n/a
Duncan Booth wrote:
Personally I think the concept of a specific path type is a good one, but
subclassing string just cries out to me as the wrong thing to do.
I disagree. I've tried using a class which wasn't derived from
a basestring and kept running into places where it didn't work well.
For example, "open" and "mkdir" take strings as input. There is no
automatic coercion.
class Spam: .... def __getattr__(self, name):
.... print "Want", repr(name)
.... raise AttributeError, name
.... open(Spam()) Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: coercing to Unicode: need string or buffer, instance found import os
os.mkdir(Spam()) Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: coercing to Unicode: need string or buffer, instance found


The solutions to this are:
1) make the path object be derived from str or unicode. Doing
this does not conflict with any OO design practice (eg, Liskov
substitution).

2) develop a new "I represent a filename" protocol, probably done
via adapt().

I've considered the second of these but I think it's a more
complicated solution and it won't fit well with existing APIs
which do things like
if isinstance(input, basestring):
input = open(input, "rU")
for line in input:
print line

I showed several places in the stdlib and in 3rd party packages
where this is used.

In other words, to me a path represents something in a filesystem,
Being picky - or something that could be in a filesystem.
the fact that it
has one, or indeed several string representations does not mean that the
path itself is simply a more specific type of string.
I didn't follow this.
You should need an explicit call to convert a path to a string and that
forces you when passing the path to something that requires a string to
think whether you wanted the string relative, absolute, UNC, uri etc.
You are broadening the definition of a file path to include URIs?
That's making life more complicated. Eg, the rules for joining
file paths may be different than the rules for joining URIs.
Consider if I have a file named "mail:da***@example.com" and I
join that with "file://home/dalke/badfiles/".

Additionally, the actions done on URIs are different than on file
paths. What should os.listdir("http://www.python.org/") do?

As I mentioned, I tried some classes which emulated file
paths. One was something like

class TempDir:
"""removes the directory when the refcount goes to 0"""
def __init__(self):
self.filename = ... use a function from the tempfile module
def __del__(self):
if os.path.exists(self.filename):
shutil.rmtree(self.filename)
def __str__(self):
return self.filename

I could do

dirname = TempDir()

but then instead of

os.mkdir(dirname)
tmpfile = os.path.join(dirname, "blah.txt")

I needed to write it as

os.mkdir(str(dirname))
tmpfile = os.path.join(str(dirname), "blah.txt"))

or have two variables, one which could delete the
directory and the other for the name. I didn't think
that was good design.
If I had derived from str/unicode then things would
have been cleaner.

Please note, btw, that some filesystems are unicode
based and others are not. As I recall, one nice thing
about the path module is that it chooses the appropriate
base class at import time. My "str()" example above
does not and would fail on a Unicode filesystem aware
Python build.
It may even be that we need a hierarchy of path
classes: URLs need similar but not identical manipulations
to file paths, so if we want to address the failings
of os.path perhaps we should also look at the failings
of urlparse at the same time.


I've found that hierarchies are rarely useful compared
to the number of times they are proposed and used. One
of the joys to me of Python is its deemphasis of class
hierarchies.

I think the same is true here. File paths and URIs are
sufficiently different that there are only a few bits
of commonality between them. Consider 'split' which
for files creates (dirname, filename) while for urls
it creates (scheme, netloc, path, query, fragment)

Andrew
da***@dalkescientific.com

Jul 22 '05 #39

P: n/a
George Sakkis wrote:
You're right, conceptually a path
HAS_A string description, not IS_A string, so from a pure OO point of
view, it should not inherit string.


How did you decide it's "has-a" vs. "is-a"?

All C calls use a "char *" for filenames and paths,
meaning the C model file for the filesystem says
paths are strings.

Paths as strings fit the Liskov substitution principle
in that any path object can be used any time a
string is used (eg, "loading from " + filename)

Good information hiding suggests that a better API
is one that requires less knowledge. I haven't
seen an example of how deriving from (unicode)
string makes things more complicated than not doing so.

Andrew
da***@dalkescientific.com

Jul 22 '05 #40

P: n/a
Duncan Booth wrote:
BTW, does it matter at all in practical use that the base class of path
varies between str and unicode depending on the platform?


Isn't it even worse than this?
On Win2K & XP, don't the file systems have something to do with the
encoding? So D: (a FAT drive) might naturally be str, while C:
(an NTFS drive) might naturally be unicode. Even worse, would be a
path that switches in the middle (which it might do if we get to a
ZIP file or use the newer dir-in-file file systems.

--Scott David Daniels
Sc***********@Acm.Org
Jul 22 '05 #41

P: n/a
John Roth wrote:
However, a path as a sequence of characters has even less
meaning - I can't think of a use, while I have an application
where traversing a path as a sequence of path elements makes
perfect sense: I need to descend the directory structure, directory
by directory, looking for specific files and types.


I *have* used a path as a sequence of characters before. I had to deal
with a bunch of filenames that were formatted like "file_02832.a.txt"

I can see the case for a path as a sequence of elements, although in
practice, drive letters, extensions, and alternate streams complicate
things.

But as the discussion here unfolds I'm starting to feel that the
advantages of using a possibly more "meaningful" approach to path as a
sequence of elements are overwhelmed by the practical advantages of
using a basestring. Mainly, that you can use it anywhere a basestring
would be used today and it Just Works.
--
Michael Hoffman
Jul 22 '05 #42

P: n/a

"Daniel Dittmar" <da************@sap.corp> wrote in message
news:db**********@news.sap-ag.de...
Duncan Booth wrote:
I would have expected a
path object to be a sequence of path elements rather than a sequence of
characters.

Glad I'm not the only oddball.
Maybe it's nitpicking, but I don't think that a path object should be a
'sequence of path elements' in an iterator context.

This means that

for element in pathobject:

has no intuitive meaning for me, so it shouldn't be allowed.


???? The internal equivalent of (simplified, omitting error checking,
etc.)

for dir in pathobject:
if isdir(dir): cd(dir)

*is*, in essence, what the OS mainly does with paths (after splitting the
string representation into pieces).

Directory walks also work with paths as sequences (stacks, in particular).

Terry J. Reedy

Jul 22 '05 #43

P: n/a
Duncan Booth wrote:
BTW, does it matter at all in practical use that the base class of path
varies between str and unicode depending on the platform?


I haven't seen any problem. I confess I can't even imagine exactly what
the problem might be, since they're both subclasses of basestring,
aren't they?

And current code should have exactly the same issues when using str or
unicode in all the calls that path() merely wraps.

So does it matter in practical use when one faces this issue and is
*not* using "path"?

-Peter
Jul 22 '05 #44

P: n/a
Stefan Rank wrote:
(It would be nice to get `path`(s) easily from a `file`, at the moment
there is only file.name if I'm not mistaken).


When files are opened through a "path" object -- e.g.
path('name').open() -- then file.name returns the path object that was
used to open it.

-Peter
Jul 22 '05 #45

P: n/a
Duncan Booth wrote:
As I said elsewhere I haven't
used path for anything real, so I'm still finding surprises such as why
this doesn't do what I expect:
p = path('a/b')
q = path('c/d')
p+q
path(u'a/bc/d')


Just a note, though you probably know, that this is intended to be
written this way with path:
p / q

path(u'a/b/c/d')

-Peter
Jul 22 '05 #46

P: n/a
Reinhold Birkenfeld wrote:
FYI: I modified the path module a bit so that it fits many of the suggestions
from python-dev, and put the result in the Python CVS tree under
nondist/sandbox/path.
By the way, thanks for doing this Reinhold!
Most prominent change is that it doesn't inherit from str/unicode anymore.
I found this distinction important, because as a str subclass the Path object
has many methods that don't make sense for it.


On this topic, has anyone ask the original author (Jason Orendorff)
whether he has some background on this decision that might benefit the
discussion? Given the elegance of the design of the path module, I
would think if he has an opinion on the matter it is probably based on
more thought than any of us have given it so far.

And maybe he would even say that it was a wrong decision at the time and
he'd do it differently the next time.

-Peter
Jul 22 '05 #47

P: n/a
Hi,

2005/7/22, Michael Hoffman <ca*******@mh391.invalid>:
What is this Java Path class? I have been STFWing and have found nothing
on it in the. Indeed if you search for "Java Path class" (with quotes)
almost half of the pages are this message from Guido. ;)

Any Java hackers here want to tell us of the wonders of the Java Path
class? I would be interested in seeing how other OO languages deal with
paths.


I guess the nearest Java class comparable with path is the File class.

http://java.sun.com/j2se/1.5.0/docs/...a/io/File.html

And as I am a so called Java hacker, I highly appreciate path as a
module for my python projects and in my eyes it is the natural way to
address files/paths. At least it is more natural to me then the os,
os.path, etc. pp. bundle, that has grown over the time.

I would love to see path inside Python's stdlib.

Best regards,
Oliver

--
Oliver Andrich <ol************@gmail.com> --- http://fitheach.de/
Jul 22 '05 #48

P: n/a

"Michael Hoffman" <ca*******@mh391.invalid> wrote in message
news:db**********@gemini.csx.cam.ac.uk...
on 22.07.2005 00:21 Michael Hoffman said the following:
Any Java hackers here want to tell us of the wonders of the Java Path
class?

Ah, here it is:

http://java.sun.com/j2se/1.5.0/docs/...a/io/File.html


Very interesting. Java's File class is a system-independent "abstract
representation of file and directory pathnames" which is constructed from
and converted to system-dependent string-form pathnames (including URL/URI
file:... forms). A File consist of an optional prefix and a *sequence* of
zero or more string names.

In other words, Java's File class is what Duncan and I thought Python's
Path class might or possibly should be. So this internal representation
might be worth considering as an option. Of course, if the interface is
done right, it mostly should not make too much difference to the user.

Terry J. Reedy

Jul 22 '05 #49

P: n/a
Scott David Daniels wrote:
Duncan Booth wrote:
BTW, does it matter at all in practical use that the base class of
path varies between str and unicode depending on the platform?


Isn't it even worse than this?
On Win2K & XP, don't the file systems have something to do with the
encoding? So D: (a FAT drive) might naturally be str, while C:
(an NTFS drive) might naturally be unicode.


The current path module handles these situations at least as well as the
libraries that come with Python do. ;-)
--
Michael Hoffman
Jul 22 '05 #50

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