Package name with '.' in them: Python Bug ?

[Yannick Patois]

Hi,

Under some naming conditions of module files, it seems that python lost
class static variables values.
It seems only to append when importing a "badly" named module that
itself import a module with a static variable in it (looks complex, but
see the example below, pretty simple):

First a working example:
<<<< file: aTest.py
#! /usr/bin/env python
import imp
import A
name='B'
fp, pathname, description = imp.find_module (name)
B=imp.load_modu le(name, fp, pathname, description)
a=A.A(1)
b=B.B()

<<<< file: A.py
class A:
a=None
def __init__(self,a =None):
if (a):
A.a=a
def __str__(self):
return str(A.a)
<<<< file: B.py
import A
class B:
def __init__(self):
a=A.A()
print a

Execution:
$ ./aTest.py
1

The value 1 obtained as expected (A.a is a static value and keept as such).

If now I just *rename* file B to B.1, without any change in the code
(except name='B' become name='B.1' in aTest.py), content of B.1.py file
being exacty the same as content of B.py, I get:

$ ./aTest.py
None

Renaming B.py to B.1.py made A unable to keeps the value of it's static
variable.

Bug tested with:
Python 1.5.2
Python 2.2.2
Python 2.3.3

Any idea ? Is it well a bug ? Some feature I didnt understood ? I read
about submodule naminig using dots as separator, but I cant relate it
towhat I saw here.

Thanks.

Yannick

--
_/ Yannick Patois \______________ _______________ _______________ _______
| web: http://feelingsurfer.net/garp/ | Garp sur irc undernet |
| email: pa****@calvix.o rg | |
| ATTAC dans le Pays de Gex: http://attacgex.ouvaton.org |

[Terry Reedy]

"Yannick Patois" <pa****@calvix. org> wrote in message
news:c3******** **@sunnews.cern .ch...

Hi,

Under some naming conditions of module files, it seems that python lost
class static variables values.
Since 'static variable' is not a Python concept, I do not know what you
mean.
It seems only to append when importing a "badly" named module that
itself import a module with a static variable in it (looks complex, but
see the example below, pretty simple):

First a working example:
<<<< file: aTest.py
#! /usr/bin/env python
import imp
import A
name='B'
fp, pathname, description = imp.find_module (name)
B=imp.load_modu le(name, fp, pathname, description)
a=A.A(1)
b=B.B()

>>>>
<<<< file: A.py
class A:
a=None
def __init__(self,a =None):
if (a):
A.a=a
def __str__(self):
return str(A.a) >>>>
<<<< file: B.py
import A
class B:
def __init__(self):
a=A.A()
print a >>>>

Execution:
$ ./aTest.py
1

The value 1 obtained as expected (A.a is a static value and keept as

such).

Given that you rebound A.a to 1 from None, I especially do not know what
you mean.
If now I just *rename* file B to B.1, without any change in the code
(except name='B' become name='B.1' in aTest.py), content of B.1.py file
being exacty the same as content of B.py, I get:
As you seem to be aware, Python expects modules to have a 'nice' name
consisting of
legal_Python_in dentifier.py. If you evade this, you are a bit on your own
and may run into untested corner cases.
$ ./aTest.py
None

Renaming B.py to B.1.py made A unable to keeps the value of it's static
variable.
It seems to me that it *kept* its original value. I would put more print
statements into both A.A and B.B and maybe even aTest.py to see where
execution first differs.
Bug tested with:
Python 1.5.2
Python 2.2.2
Python 2.3.3

Any idea ? Is it well a bug ? Some feature I didnt understood ? I read
about submodule naminig using dots as separator, but I cant relate it
towhat I saw here.

import b.b1 would normally mean import file (module) b1 in the b package
directory. But imp obviously did not find fine '1' in a 'B' directory.

Terry J. Reedy

[Yannick Patois]

Hi,
Terry Reedy wrote:

"Yannick Patois" <pa****@calvix. org> wrote in message

Under some naming conditions of module files, it seems that python lost
class static variables values. Since 'static variable' is not a Python concept, I do not know what you
mean.

As you're so smart and you read the following, how do you call 'a' in
class A ?
That's what I want to qualify.

The value 1 obtained as expected (A.a is a static value and keept as

such).
Given that you rebound A.a to 1 from None, I especially do not know what
you mean.

I dont understand.

If now I just *rename* file B to B.1, without any change in the code
(except name='B' become name='B.1' in aTest.py), content of B.1.py file
being exacty the same as content of B.py, I get:

As you seem to be aware, Python expects modules to have a 'nice' name
consisting of
legal_Python_in dentifier.py.

Which are ? Where to find this info ?
If you evade this, you are a bit on your own
and may run into untested corner cases.
Untested area contains bugs, that's why it's interesting to test them.

$ ./aTest.py
None
Renaming B.py to B.1.py made A unable to keeps the value of it's static
variable.

It seems to me that it *kept* its original value.

However you called it, it doesnt behave the same (and doesnt behave the
way python should work). The change is only a file name, no more.
I would put more print
statements into both A.A and B.B and maybe even aTest.py to see where
execution first differs.
It breaks in B, if I remember well.

Any idea ? Is it well a bug ? Some feature I didnt understood ? I read
about submodule naminig using dots as separator, but I cant relate it
towhat I saw here.

import b.b1 would normally mean import file (module) b1 in the b package
directory.

It's not the case here: would have it be that the import statement would
have broke with "cant find that module".
But imp obviously did not find fine '1' in a 'B' directory.

It didnt seek for it, it just loaded 'B.1' as asked. Everything seems to
work, except that some internal python dictionnary has likely been
corrupted.

Correct behavior would either be "break on 'cant import module 1 from
B'" or "correctly import B.1 without corrupting anything."

To me, that's look to be a bug.

Yannick

--
_/ Yannick Patois \______________ _______________ _______________ _______
| web: http://feelingsurfer.net/garp/ | Garp sur irc undernet |
| email: pa****@calvix.o rg | |
| ATTAC dans le Pays de Gex: http://attacgex.ouvaton.org |

[Stephen Robert Norris]

On Fri, 19 Mar 2004 19:12:03 +0100, Yannick Patois wrote:

Hi,
Terry Reedy wrote:

"Yannick Patois" <pa****@calvix. org> wrote in message

Under some naming conditions of module files, it seems that python lost
class static variables values. Since 'static variable' is not a Python concept, I do not know what you
mean.

As you're so smart and you read the following, how do you call 'a' in
class A ?
That's what I want to qualify.

There's no need to be hostile. I'd call it a class variable. It's
certainly not static in any sense of the word I'd use.

The value 1 obtained as expected (A.a is a static value and keept as

such).
Given that you rebound A.a to 1 from None, I especially do not know
what you mean.

I dont understand.

You explicitly construct the A instance with 1, so what do you expect to
happen? A.a is set to None as a class variable, then changed to 1 by the
constructor.

If now I just *rename* file B to B.1, without any change in the code
(except name='B' become name='B.1' in aTest.py), content of B.1.py file
being exacty the same as content of B.py, I get:
As you seem to be aware, Python expects modules to have a 'nice' name
consisting of
legal_Python_in dentifier.py.

Which are ? Where to find this info ?

Check the Python Reference Manual.

If you evade this, you are a bit on your own
and may run into untested corner cases.
Untested area contains bugs, that's why it's interesting to test them.

The only potential bug here is that perhaps python should have raised an
error when the import happened.
To me, that's look to be a bug.

Yannick

I think the bug is in how you understand Python, not in python.

Stephen

[John Roth]

"Yannick Patois" <pa****@calvix. org> wrote in message
news:c3******** **@sunnews.cern .ch...

Hi,

Under some naming conditions of module files, it seems that python lost
class static variables values.
There is no such thing as a static variable in Python.
It seems only to append when importing a "badly" named module that
itself import a module with a static variable in it (looks complex, but
see the example below, pretty simple):
There is no such thing as a static variable in Python.

First a working example:
<<<< file: aTest.py
#! /usr/bin/env python
import imp
import A
name='B'
fp, pathname, description = imp.find_module (name)
B=imp.load_modu le(name, fp, pathname, description)
a=A.A(1)
b=B.B()

>>>>
<<<< file: A.py
class A:
a=None
def __init__(self,a =None):
if (a):
A.a=a
def __str__(self):
return str(A.a) >>>>
<<<< file: B.py
import A
class B:
def __init__(self):
a=A.A()
print a >>>>

Execution:
$ ./aTest.py
1

The value 1 obtained as expected (A.a is a static value and keept as

such).
If now I just *rename* file B to B.1, without any change in the code
(except name='B' become name='B.1' in aTest.py), content of B.1.py file
being exacty the same as content of B.py, I get:
[...]

"B.1" is not a legal file name from an import perspective. The manual
description for find_module says: "The function does not handle hierarchical
module names (names containing dots)."

John Roth


Thanks.

Yannick

[Terry Reedy]

"Yannick Patois" <pa****@calvix. org> wrote in message
news:c3******** **@sunnews.cern .ch...

Terry Reedy wrote:

Since 'static variable' is not a Python concept, I do not know what you
mean.

how do you call 'a' in class A ?
(non-method) attribute, possibly 'member' (of class A).

Given that you rebound A.a to 1 from None, I especially do not know what you mean.

I dont understand.

When you call this class
<<<< file: A.py
class A:
a=None
def __init__(self,a =None):
if (a):
A.a=a
with the statement a=A.A(1), you enter __init__ with a==1, trigger the
if(a) [if(1)]conditional and execute A.a=a [A.a=1], thereby rebinding class
attribute a from None, as originally set, to 1. Leaving aside the misuse
of 'static' in C, 'static' usually means 'unchanging', whereas you change
A.a.

As you seem to be aware, Python expects modules to have a 'nice' name
consisting of
legal_Python_in dentifier.py.

Which are ? Where to find this info ?

Tutorial I presume, definitely Reference Manual under 'names' and/or
'identifiers'.

If you evade this, you are a bit on your own
and may run into untested corner cases.

Untested area contains bugs, that's why it's interesting to test them.

Yes, I have done similar things.

I would put more print statements into both A.A and B.B
and maybe even aTest.py to see where execution first differs.

To restate: if I were to investigate further, I would add prints
statements, since that has so far worked well for me with Python. What you
do is up to you.
It breaks in B, if I remember well.

In what way? Since the line 'a=A.A(1)', should still rebind A.a, it is
puzzling that the following line 'b=B.B()' should act any differently. The
only thing I can think of is that the name change caused the line 'import
A' to import A under a different internal name so that module A in B is no
longer that same as module A in aTest. I would test this by putting 'print
id(A)' in both files after the imports. I would also add

import sys
print sys.modules

to the end of aTest. I suspect that this will clear up the mystery.

Terry J. Reedy

[Stewart Midwinter]

Yannick Patois <pa****@calvix. org> wrote in message news:<c3******* ***@sunnews.cer n.ch>...

If now I just *rename* file B to B.1, without any change in the code
(except name='B' become name='B.1' in aTest.py), content of B.1.py file
being exacty the same as content of B.py, I get:
.....
Any idea ? Is it well a bug ? Some feature I didnt understood ? I read
about submodule naminig using dots as separator, but I cant relate it
towhat I saw here.

Salut Yannick:

J'ose offrir une réponse....

I work with submodules. They're in some folder, which has subfolders
(call them fbm, uti, and a few others). If I place an empty file in
my root folder called __init__.py, I can refer to modules in the
subfolders by a dot notation. For example, if I have a file
process.py in subfolder fbm, I can say:
import fbm.process

I speculate that when you renamed B to B.1, Python interpreted your
intent to import a module called 1 in subfolder B.

J'espère que cela aide un peu!

Stewart

[Yannick Patois]

Stephen Robert Norris wrote:

On Fri, 19 Mar 2004 19:12:03 +0100, Yannick Patois wrote:
The only potential bug here is that perhaps python should have raised an
error when the import happened.

The doc explicitly says:
"his function does not handle hierarchical module names (names
containing dots)."

So you may say that it's up to the programmer to comply with the doc,
and shouldnt expect things to work well if not.

But, I dont want to handle a hierarchical module: just a non
hierarchical one that appends to have a dot in it's name, and it's not
so explicit that this would break.

The fact that it "almost" work is even more strange, and error prone.

But I dont know, I wont say that this has to be fixed in any way outside
of the programmer's code.

Yannick

--
_/ Yannick Patois \______________ _______________ _______________ _______
| web: http://feelingsurfer.net/garp/ | Garp sur irc undernet |
| email: pa****@calvix.o rg | |
| ATTAC dans le Pays de Gex: http://attacgex.ouvaton.org |

[Yannick Patois]

Terry Reedy wrote:

"Yannick Patois" <pa****@calvix. org> wrote in message To restate: if I were to investigate further, I would add prints
statements, since that has so far worked well for me with Python. What you
do is up to you.

Since it seems to be definitly illegal, it would only worth further work
if I would somehow 'fix' python to work with this kind of names, which
is both above my skills and likely unwanted. Having a clear error
message at import time would be nice anyway.

Yannick

--
_/ Yannick Patois \______________ _______________ _______________ _______
| web: http://feelingsurfer.net/garp/ | Garp sur irc undernet |
| email: pa****@calvix.o rg | |
| ATTAC dans le Pays de Gex: http://attacgex.ouvaton.org |

[Josiah Carlson]

> But I dont know, I wont say that this has to be fixed in any way outside

of the programmer's code.

I've never seen python modules named like: valid_name.1.py

Considering that you have shown that it does not work, and that there is
documentation stating that it is not /meant/ to work, then the error is
in the way /you/ name /your/ modules, not the way Python handles
/incorrectly/ named modules.

- Josiah