Calling foreign functions from Python? ctypes?

[Paul Watson]

I need to call some Windows APIs. Is the only way to download ctypes or
the win32 interfaces? Is there any plan to get ctypes batteries into
the standard Python build?

[Martin v. Löwis]

Re: Calling foreign functions from Python? ctypes?

Paul Watson wrote:[color=blue]
> I need to call some Windows APIs. Is the only way to download ctypes or
> the win32 interfaces?[/color]

That depends on the specific win32 interface you want to call.
Typically, the answer is "yes".
[color=blue]
> Is there any plan to get ctypes batteries into the standard Python build?[/color]

I don't have such a plan. To my knowledge, ctypes has never been
contributed to Python, either, so its author apparently has no plan,
either.

Regards,
Martin

[Neil Hodgson]

Re: Calling foreign functions from Python? ctypes?

Paul Watson:
[color=blue]
> Is there any plan to get ctypes batteries into
> the standard Python build?[/color]

It is unlikely that ctypes will be included in the standard Python
build as it allows unsafe memory access making it much easier to crash
Python.

Neil

[Paul Rubin]

Re: Calling foreign functions from Python? ctypes?

"Martin v. Löwis" <martin@v.loewi s.de> writes:[color=blue]
> To my knowledge, ctypes has never been contributed to Python,
> either, so its author apparently has no plan, either.[/color]

Has anyone from Python.org asked him or her?

[Martin v. Löwis]

Re: Calling foreign functions from Python? ctypes?

Paul Rubin wrote:[color=blue][color=green]
>>To my knowledge, ctypes has never been contributed to Python,
>>either, so its author apparently has no plan, either.[/color]
>
>
> Has anyone from Python.org asked him or her?[/color]

I can't answer that question. I haven't (and I personally
share Neil Hodgson's reservation wrt. to the possibility
of crashing the interpreter).

Regards,
Martin

[Paul Watson]

Re: Calling foreign functions from Python? ctypes?

Neil Hodgson wrote:[color=blue]
> Paul Watson:
>[color=green]
>> Is there any plan to get ctypes batteries into the standard Python build?[/color]
>
>
> It is unlikely that ctypes will be included in the standard Python
> build as it allows unsafe memory access making it much easier to crash
> Python.[/color]

Does extending Python with any C/C++ function not do the same thing?

[Paul Watson]

Re: Calling foreign functions from Python? ctypes?

Martin v. Löwis wrote:[color=blue]
> Paul Watson wrote:
>[color=green]
>>I need to call some Windows APIs. Is the only way to download ctypes or
>>the win32 interfaces?[/color]
>
>
> That depends on the specific win32 interface you want to call.
> Typically, the answer is "yes".[/color]

I have used _winreg and I see winsound in the doc.

I need to call GetVersionInfo( ) and handle VERSIONINFO information. I
thought that distutils might have something, but I do not see it yet.
Any suggestions?

[Neil Hodgson]

Re: Calling foreign functions from Python? ctypes?

Paul Watson:
[color=blue]
> Neil Hodgson wrote:[color=green]
>> It is unlikely that ctypes will be included in the standard Python
>> build as it allows unsafe memory access making it much easier to crash
>> Python.[/color]
> Does extending Python with any C/C++ function not do the same thing?[/color]

No. It is the responsibility of the extension author to ensure that
there is no possibility of crashing Python. With ctypes, you have a
generic mechanism that enables Python code to cause a crash.

Neil

[Paul Rubin]

Re: Calling foreign functions from Python? ctypes?

Neil Hodgson <nyamatongwe+th under@gmail.com > writes:[color=blue]
> No. It is the responsibility of the extension author to ensure
> that there is no possibility of crashing Python. With ctypes, you have
> a generic mechanism that enables Python code to cause a crash.[/color]

http://docs.python.org/lib/module-dl.html

would seem to also do that.

[Martin v. Löwis]

Re: Calling foreign functions from Python? ctypes?

Paul Watson wrote:[color=blue]
> I need to call GetVersionInfo( ) and handle VERSIONINFO information. I
> thought that distutils might have something, but I do not see it yet.
> Any suggestions?[/color]

You could write this specific API in VB, and then run cscript.exe in
a pipe; or you could write a wrapper module just for that specific
API (in case PythonWin is too large for you).

Regards,
Martin

[Martin v. Löwis]

Re: Calling foreign functions from Python? ctypes?

Paul Rubin wrote:[color=blue]
> http://docs.python.org/lib/module-dl.html
> would seem to also do that.[/color]

That's correct. It has the same (unhealable) flaw.
No surprise, though: it provides the same functionality.

Regards,
Martin

[Carl Friedrich Bolz]

Re: Calling foreign functions from Python? ctypes?

Jean-Paul Calderone wrote:[color=blue]
>
> I could probably dig up a few more, if you want. So what's ctypes on top of this?
>[/color]

another one:

cfbolz@gauss:~$ python
Python 2.4.2 (#2, Sep 30 2005, 21:19:01)
[GCC 4.0.2 20050808 (prerelease) (Ubuntu 4.0.1-4ubuntu8)] on linux2
Type "help", "copyright" , "credits" or "license" for more information.[color=blue][color=green][color=darkred]
>>> import weakref
>>> ref = None
>>> class Target:[/color][/color][/color]
.... def __del__(self):
.... global ref
.... ref = weakref.ref(sel f)
....[color=blue][color=green][color=darkred]
>>> def g():[/color][/color][/color]
.... w = Target()
.... w = None
.... print ref()
....[color=blue][color=green][color=darkred]
>>> g()[/color][/color][/color]
Segmentation fault

There are dozends of segfaults in Python indeed.

Cheers,

Carl Friedrich Bolz

[Paul Watson]

Re: Calling foreign functions from Python? ctypes?

Martin v. Löwis wrote:[color=blue]
> Paul Watson wrote:
>[color=green]
>>I need to call GetVersionInfo( ) and handle VERSIONINFO information. I
>>thought that distutils might have something, but I do not see it yet.
>>Any suggestions?[/color]
>
> You could write this specific API in VB, and then run cscript.exe in
> a pipe; or you could write a wrapper module just for that specific
> API (in case PythonWin is too large for you).[/color]

I cannot find any way to get to GetVersionInfo in VBScript (cscript).

If so, this appears to leave me with no choice but to produce a Windows
executable, whether a .exe or C code wrapped from Python. Right?

[Martin v. Löwis]

Re: Calling foreign functions from Python? ctypes?

Paul Watson wrote:[color=blue]
> I cannot find any way to get to GetVersionInfo in VBScript (cscript).[/color]

Well, in VB6, you have ctypes. So you can call any API function you
like to.

For one implementation, see

http://www.andreavb.com/tip030020.html

Regards,
Martin

[Thomas Heller]

Re: Calling foreign functions from Python? ctypes?

"=?UTF-8?B?Ik1hcnRpbiB 2LiBMw7Z3aXMi?= " <martin@v.loewi s.de> writes:
[color=blue]
> Paul Watson wrote:[color=green]
>> I need to call some Windows APIs. Is the only way to download ctypes or
>> the win32 interfaces?[/color]
>
> That depends on the specific win32 interface you want to call.
> Typically, the answer is "yes".
>[color=green]
>> Is there any plan to get ctypes batteries into the standard Python build?[/color]
>
> I don't have such a plan. To my knowledge, ctypes has never been
> contributed to Python, either, so its author apparently has no plan,
> either.[/color]

As the author, I would be happy to see ctypes included with the standard
Python build.

Thomas