Should a Python module not intended to be executed have shebang/
hashbang (e.g., "#!/usr/bin/env python") or not? I'm used to having a
shebang in every .py file but I recently heard someone argue that
shebangs were only appropriate for Python code intended to be
executable (i.e., run from the command line).
13  4450 
On Apr 11, 5:29 pm, "Chris Lasher" <chris.las...@gmail.comwrote:
Should a Python module not intended to be executed have shebang/
hashbang (e.g., "#!/usr/bin/env python") or not? I'm used to having a
shebang in every .py file but I recently heard someone argue that
shebangs were only appropriate for Python code intended to be
executable (i.e., run from the command line).
If you don't intend the module to be executable then adding a shebang
line and/or setting the files execute bit are both contrary to
intended use. You should therefore leave out the shebang/not set the
execute bit to emphasise your intended use.
During development however, intended use may differ from use when
deployed.
- Paddy.
Chris Lasher a écrit :
Should a Python module not intended to be executed have shebang/
hashbang (e.g., "#!/usr/bin/env python") or not?
The shebang is only useful for files that you want to make directly
executable on a *n*x system. They are useless on Windows, and not
technically required to use the file as a main program -ie: you can
always run it like this:
$ /path/to/python filename.py
I'm used to having a
shebang in every .py file
An encoding declaration might be more useful IMHO !-)
"Chris Lasher" <ch**********@gmail.comwrites:
I recently heard someone argue that shebangs were only appropriate
for Python code intended to be executable (i.e., run from the
command line).
Since that's the purpose of putting in a shebang line, that's what I'd
argue also; specifically:
- Modules intended primarily for import should be named 'foo.py' and
have no shebang line.
This doesn't preclude having an 'if __name__ == "__main__":'
block, and running the module as 'python ./foo.py' for whatever
reason.
- Modules intended primarily for running as a command should have a
shebang line and an 'if __name__ == "__main__":' block, and be
named according to the conventions of the OS for naming command
programs; on *nix, this means naming the file 'foo'.
This doesn't preclude importing the module (e.g. for unit
testing), though it is a little more convoluted than a simple
'import' statement.
--
\ "Dad always thought laughter was the best medicine, which I |
`\ guess is why several of us died of tuberculosis." -- Jack |
_o__) Handey |
Ben Finney
On Thu, 12 Apr 2007 00:24:12 +0200, Bruno Desthuilliers <bd*****************@free.quelquepart.frwrote:
Chris Lasher a écrit :
>Should a Python module not intended to be executed have shebang/
hashbang (e.g., "#!/usr/bin/env python") or not?
The shebang is only useful for files that you want to make directly
executable on a *n*x system. They are useless on Windows,
Probably (unless setup.py uses them for something meaningful there,
too). But of course often you don't know that the file will always be
used only on Windows, or that the Windows user won't prefer Cygwin.
and not
technically required to use the file as a main program -ie: you can
always run it like this:
$ /path/to/python filename.py
You can, but sometimes it's not appropriate. If you distribute a
Python program to Unix users in that form, they may not want to know
or care which language it's written in. Especially if you decide, a
few releases later, that you want to switch to Perl or something.
I realise that you took a more narrow view than I do above, so
please see this as additional notes rather than critisism. It's just
that I am struggling with people at work who feel program names
should encode whatever language they happen to be written in, and so
I am a bit oversensitive ...
>I'm used to having a
shebang in every .py file
An encoding declaration might be more useful IMHO !-)
They are not mutually exclusive, if that is what you mean.
I always use both.
/Jorgen
--
// Jorgen Grahn <grahn@ Ph'nglui mglw'nafh Cthulhu
\X/ snipabacken.dyndns.org R'lyeh wgah'nagl fhtagn!
On 13 Apr 2007 10:54:18 GMT, Jorgen Grahn <gr********@snipabacken.dyndns.orgwrote:
On Thu, 12 Apr 2007 00:24:12 +0200, Bruno Desthuilliers <bd*****************@free.quelquepart.frwrote:
>Chris Lasher a écrit :
>>Should a Python module not intended to be executed have shebang/
hashbang (e.g., "#!/usr/bin/env python") or not?
The shebang is only useful for files that you want to make directly
executable on a *n*x system. They are useless on Windows,
Probably (unless setup.py uses them for something meaningful there,
too).
There's another, secondary, reason to use a shebang on Python source
which isn't executable: the Unix file(1) command and friends can see
that it's Python code.
(Of course, such files will almost always be named foo.py.)
/Jorgen
--
// Jorgen Grahn <grahn@ Ph'nglui mglw'nafh Cthulhu
\X/ snipabacken.dyndns.org R'lyeh wgah'nagl fhtagn!
Jorgen Grahn a écrit :
On Thu, 12 Apr 2007 00:24:12 +0200, Bruno Desthuilliers <bd*****************@free.quelquepart.frwrote:
>>Chris Lasher a écrit :
>>>Should a Python module not intended to be executed have shebang/
hashbang (e.g., "#!/usr/bin/env python") or not?
The shebang is only useful for files that you want to make directly
executable on a *n*x system. They are useless on Windows,
Probably (unless setup.py uses them for something meaningful there,
too). But of course often you don't know that the file will always be
used only on Windows, or that the Windows user won't prefer Cygwin.
From a practical POV, I consider cygwin as a *n*x system. And FWIW, I
mentionned this platform specificness because it might not be clear to
anyone reading the OP.
>
>>and not
technically required to use the file as a main program -ie: you can
always run it like this:
$ /path/to/python filename.py
You can, but sometimes it's not appropriate.
That's another question. What I meant here is that you don't technically
need the shebang and x bit to allow execution of a Python file. IOW, the
shebang is only meaningfull for python files intented to be effectivly
used as a program.
If you distribute a
Python program to Unix users in that form, they may not want to know
or care which language it's written in. Especially if you decide, a
few releases later, that you want to switch to Perl or something.
<troll>
No one in it's own mind would decide to switch from Python to Perl !-)
</troll>
More seriously, and as far as I'm concerned, when I want to make a
python script (by opposition to a python 'module') available as a unix
command, I either use a symlink or a shell script calling the python
script.
I realise that you took a more narrow view than I do above,
I mostly tried to answer the OP question.
so
please see this as additional notes rather than critisism. It's just
that I am struggling with people at work who feel program names
should encode whatever language they happen to be written in,
OMG.
and so
I am a bit oversensitive ...
I can understand this...
>
>>>I'm used to having a
shebang in every .py file
An encoding declaration might be more useful IMHO !-)
They are not mutually exclusive, if that is what you mean.
Of course not. But one is always usefull (and will become more or less
mandatory in a near future IIRC), while the other is either totally
useless (module files) or only partially useful (script files).
I always use both.
Even in modules ?????
On Fri, 13 Apr 2007 22:46:03 +0200, Bruno Desthuilliers <bd*****************@free.quelquepart.frwrote:
Jorgen Grahn a écrit :
....
>If you distribute a
Python program to Unix users in that form, they may not want to know
or care which language it's written in. Especially if you decide, a
few releases later, that you want to switch to Perl or something.
<troll>
No one in it's own mind would decide to switch from Python to Perl !-)
</troll>
I was trolling a bit, too ;-)
Actually, it made sense in my case. It was a typical Perl task -- a
filter regex-parsing a huge (a few hundred megabytes) text file.
Rewriting it in Perl for speed was faster and more readable than
rewriting it in Python for speed.
More seriously, and as far as I'm concerned, when I want to make a
python script (by opposition to a python 'module') available as a unix
command, I either use a symlink or a shell script calling the python
script.
A symlink yes, but a shell script? Wouldn't it be easier to write a
one-liner (well, two-liner) Python script in that case?
>>>>I'm used to having a
shebang in every .py file
An encoding declaration might be more useful IMHO !-)
....
>I always use both.
Even in modules ?????
Yes, for a few reasons:
- file(1) can tell it's Python source
- I tend to leave unit tests in my modules
- I just started doing that when I first tried Python;
it's part of my mental boilerplate
I don't claim they are good reasons. And since I strongly dislike
setting the execute bit on things that aren't executable, I should
probably stop using the shebang everywhere, too ...
/Jorgen
--
// Jorgen Grahn <grahn@ Ph'nglui mglw'nafh Cthulhu
\X/ snipabacken.dyndns.org R'lyeh wgah'nagl fhtagn!
Jorgen Grahn a écrit :
On Fri, 13 Apr 2007 22:46:03 +0200, Bruno Desthuilliers <bd*****************@free.quelquepart.frwrote:
>>Jorgen Grahn a écrit :
(snip)
>
>>More seriously, and as far as I'm concerned, when I want to make a
python script (by opposition to a python 'module') available as a unix
command, I either use a symlink or a shell script calling the python
script.
A symlink yes, but a shell script? Wouldn't it be easier to write a
one-liner (well, two-liner) Python script in that case?
Not necessarily. Just like there are cases where it makes sens to use
Perl instead of Python, some things are really far simpler to do with
shell scripts...
Chris Lasher wrote:
Should a Python module not intended to be executed have shebang/
hashbang (e.g., "#!/usr/bin/env python") or not? I'm used to having a
shebang in every .py file but I recently heard someone argue that
shebangs were only appropriate for Python code intended to be
executable (i.e., run from the command line).
Personally I include it in all of them, as part of boilerplate in a
template.
--
Michael Hoffman
On Saturday, Apr 21st 2007 at 19:18 +0100, quoth Michael Hoffman:
=>Chris Lasher wrote:
=>Should a Python module not intended to be executed have shebang/
=>hashbang (e.g., "#!/usr/bin/env python") or not? I'm used to having a
=>shebang in every .py file but I recently heard someone argue that
=>shebangs were only appropriate for Python code intended to be
=>executable (i.e., run from the command line).
=>
=>Personally I include it in all of them, as part of boilerplate in a
=>template.
I'd recommend againt it. The shebang doesn't do you any good unless it's
also in the presence of a file that has its executable bit set.
For example, let's leave python out for a second: I have a shell script.
And I also have lots of files which are not intended to be executed which
are also shell scripts, but which are sucked in by the shell "." or
"source" command (which is *somewhat* analogous to python's import). Lots
of these shell "library" scripts can't execute as standalone. The same
thing is possible with pything scripts.
Of course, anything that has
if __name__ == "__main__":
in it should always have a shebang and be executable.
--
Time flies like the wind. Fruit flies like a banana. Stranger things have .0.
happened but none stranger than this. Does your driver's license say Organ ..0
Donor?Black holes are where God divided by zero. Listen to me! We are all- 000
individuals! What if this weren't a hypothetical question?
steveo at syslang.net
Steven W. Orr wrote:
On Saturday, Apr 21st 2007 at 19:18 +0100, quoth Michael Hoffman:
=>Chris Lasher wrote:
=>Should a Python module not intended to be executed have shebang/
=>hashbang (e.g., "#!/usr/bin/env python") or not? I'm used to having a
=>shebang in every .py file but I recently heard someone argue that
=>shebangs were only appropriate for Python code intended to be
=>executable (i.e., run from the command line).
=>
=>Personally I include it in all of them, as part of boilerplate in a
=>template.
I'd recommend againt it. The shebang doesn't do you any good unless it's
also in the presence of a file that has its executable bit set.
It doesn't do any bad either, so I don't understand why you would
recommend against it.
And the bash function I use to create new files from the template also
does chmod a+x.
Not to mention that I have emacs set such that things with shebangs at
the top are automatically chmod a+x, so in my programming environment,
having a shebang on files I create and being executable are one and the
same.
For example, let's leave python out for a second: I have a shell script.
And I also have lots of files which are not intended to be executed which
are also shell scripts, but which are sucked in by the shell "." or
"source" command (which is *somewhat* analogous to python's import). Lots
of these shell "library" scripts can't execute as standalone. The same
thing is possible with pything scripts.
Of course, anything that has
if __name__ == "__main__":
in it should always have a shebang and be executable.
That's in my template as well. :)
I try to write all my modules so that they can easily be adapted to run
as scripts, and all my scripts so that they can easily be adapted to use
as modules. This has served me well many, many times. I see no reasons
to create an artificial barrier to doing this by leaving the shebang out
of files where it has no ill effect.
--
Michael Hoffman
Michael Hoffman wrote:
Steven W. Orr wrote:
>On Saturday, Apr 21st 2007 at 19:18 +0100, quoth Michael Hoffman:
=>Chris Lasher wrote:
=>Should a Python module not intended to be executed have shebang/
=>hashbang (e.g., "#!/usr/bin/env python") or not? I'm used to having a
=>shebang in every .py file but I recently heard someone argue that
=>shebangs were only appropriate for Python code intended to be
=>executable (i.e., run from the command line).
=>
=>Personally I include it in all of them, as part of boilerplate in a
=>template.
I'd recommend againt it. The shebang doesn't do you any good unless it's
also in the presence of a file that has its executable bit set.
It doesn't do any bad either, so I don't understand why you would
recommend against it.
And the bash function I use to create new files from the template also
does chmod a+x.
Not to mention that I have emacs set such that things with shebangs at
the top are automatically chmod a+x, so in my programming environment,
having a shebang on files I create and being executable are one and the
same.
>For example, let's leave python out for a second: I have a shell script.
And I also have lots of files which are not intended to be executed which
are also shell scripts, but which are sucked in by the shell "." or
"source" command (which is *somewhat* analogous to python's import). Lots
of these shell "library" scripts can't execute as standalone. The same
thing is possible with pything scripts.
Of course, anything that has
if __name__ == "__main__":
in it should always have a shebang and be executable.
That's in my template as well. :)
I try to write all my modules so that they can easily be adapted to run
as scripts, and all my scripts so that they can easily be adapted to use
as modules. This has served me well many, many times. I see no reasons
to create an artificial barrier to doing this by leaving the shebang out
of files where it has no ill effect.
If you ever create a module that *shouldn't be run you can always put
if __name__ == "__main__":
print "Do not run this script: it is a module for import only"
at the end of it. But what's the point?
regards
Steve
--
Steve Holden +1 571 484 6266 +1 800 494 3119
Holden Web LLC/Ltd http://www.holdenweb.com
Skype: holdenweb http://del.icio.us/steve.holden
Recent Ramblings http://holdenweb.blogspot.com
On Monday, Apr 23rd 2007 at 17:31 +0100, quoth Michael Hoffman:
=>Steven W. Orr wrote:
=>On Saturday, Apr 21st 2007 at 19:18 +0100, quoth Michael Hoffman:
=>>
=>=>Chris Lasher wrote:
=>=>Should a Python module not intended to be executed have shebang/
=>=>hashbang (e.g., "#!/usr/bin/env python") or not? I'm used to having a
=>=>shebang in every .py file but I recently heard someone argue that
=>=>shebangs were only appropriate for Python code intended to be
=>=>executable (i.e., run from the command line).
=>=>
=>=>Personally I include it in all of them, as part of boilerplate in a
=>=>template.
=>>
=>I'd recommend againt it. The shebang doesn't do you any good unless it's
=>also in the presence of a file that has its executable bit set.
=>
=>It doesn't do any bad either, so I don't understand why you would
=>recommend against it.
=>
=>And the bash function I use to create new files from the template also
=>does chmod a+x.
=>
=>Not to mention that I have emacs set such that things with shebangs at
=>the top are automatically chmod a+x, so in my programming environment,
=>having a shebang on files I create and being executable are one and the
=>same.
=>
=>For example, let's leave python out for a second: I have a shell script.
=>And I also have lots of files which are not intended to be executed which
=>are also shell scripts, but which are sucked in by the shell "." or
=>"source" command (which is *somewhat* analogous to python's import). Lots
=>of these shell "library" scripts can't execute as standalone. The same
=>thing is possible with pything scripts.
=>>
=>Of course, anything that has
=>if __name__ == "__main__":
=>in it should always have a shebang and be executable.
=>
=>That's in my template as well. :)
=>
=>I try to write all my modules so that they can easily be adapted to run
=>as scripts, and all my scripts so that they can easily be adapted to use
=>as modules. This has served me well many, many times. I see no reasons
=>to create an artificial barrier to doing this by leaving the shebang out
=>of files where it has no ill effect.
We're going too far here. Anything that ever gets executed should
obviously always be executable and have a shebang. I'm trying to point out
to people who create scripts in any language, shell, python, farsi,
whatever, that if it's intended to be read in as some sort of library then
don't make it executable and don't add a shebang. To do so is to confuse
future generations.
--
Time flies like the wind. Fruit flies like a banana. Stranger things have .0.
happened but none stranger than this. Does your driver's license say Organ ..0
Donor?Black holes are where God divided by zero. Listen to me! We are all- 000
individuals! What if this weren't a hypothetical question?
steveo at syslang.net
This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
by: deko |
last post by:
In regard to running php scripts with cron -
Here is a sample script:
<?php
//debug.php
echo "<br> This is a test";
?>
I can call debug.php from a web page on my site like this:
|
by: Andres Corrada-Emmanuel |
last post by:
Hello,
Does the optimize flag work on the shebang line of UNIX systems? I've
tried to execute a script on a Solaris system with a shebang line of the
form:
#! /usr/bin/env python -O
and it...
|
by: Nick Coghlan |
last post by:
Anyone playing with the CPython interpreter's new command line switch might have
noticed that it only works with top-level modules (i.e. scripts that are
directly on sys.path). If the script is...
|
by: Nick Coghlan |
last post by:
Python 2.4's -m command line switch only works for modules directly on sys.path.
Trying to use it with modules inside packages will fail with a "Module not
found" error. This PEP aims to fix that...
|
by: rbt |
last post by:
Haven't tested this on Windows yet... thought I'd ask here:
Does the line below have any negative impact on Windows machines? I
develop and test mostly on Unix, but my scripts are often used on...
|
by: Joerg Schuster |
last post by:
Hello,
is there a way to compile a python file foo.py to foo.pyc (or foo.pyo)
such that foo.pyc can be run with 'foo.pyc' (as opposed to 'python
foo.pyc') on the command line?
Jörg Schuster
|
by: Lauren Quantrell |
last post by:
At running the risk of asking how big is too big...
Is there a rule of thumb or a best practice that says I may have too
many modules? I currently have a Access2K app with about 30 code
modules,...
|
by: veracon |
last post by:
Long story short, in order to use Python 2.5, I've compiled it in my
own account on my hosting. It works fantastic as
/home/my_username/python2.5, but the shebang is a bit long. Is there a
way to...
|
by: prakashspatil |
last post by:
what is shebang line in perl
how it executes even as it starts with comment (#).
|
by: BarryA |
last post by:
What are the essential steps and strategies outlined in the Data Structures and Algorithms (DSA) roadmap for aspiring data scientists? How can individuals effectively utilize this roadmap to progress...
|
by: nemocccc |
last post by:
hello, everyone, I want to develop a software for my android phone for daily needs, any suggestions?
|
by: Sonnysonu |
last post by:
This is the data of csv file
1 2 3
1 2 3
1 2 3
1 2 3
2 3
2 3
3
the lengths should be different i have to store the data by column-wise with in the specific length.
suppose the i have to...
|
by: Hystou |
last post by:
There are some requirements for setting up RAID:
1. The motherboard and BIOS support RAID configuration.
2. The motherboard has 2 or more available SATA protocol SSD/HDD slots (including MSATA, M.2...
|
by: marktang |
last post by:
ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However,...
|
by: Hystou |
last post by:
Most computers default to English, but sometimes we require a different language, especially when relocating. Forgot to request a specific language before your computer shipped? No problem! You can...
|
by: Oralloy |
last post by:
Hello folks,
I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>".
The problem is that using the GNU compilers,...
|
by: Hystou |
last post by:
Overview:
Windows 11 and 10 have less user interface control over operating system update behaviour than previous versions of Windows. In Windows 11 and 10, there is no way to turn off the Windows...
|
by: tracyyun |
last post by:
Dear forum friends,
With the development of smart home technology, a variety of wireless communication protocols have appeared on the market, such as Zigbee, Z-Wave, Wi-Fi, Bluetooth, etc. Each...
| |
