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Accessing dll

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  Accessing dll Helpful person <rrllff@yahoo.com> - 2012-09-06 08:07 -0700
    Re: Accessing dll Jerry Hill <malaclypse2@gmail.com> - 2012-09-06 11:30 -0400
      Re: Accessing dll Helpful person <rrllff@yahoo.com> - 2012-09-06 08:41 -0700
      Re: Accessing dll Helpful person <rrllff@yahoo.com> - 2012-09-06 08:44 -0700
        Re: Accessing dll Chris Angelico <rosuav@gmail.com> - 2012-09-07 22:15 +1000
          Re: Accessing dll Helpful person <rrllff@yahoo.com> - 2012-09-07 10:27 -0700
            Re: Accessing dll Chris Angelico <rosuav@gmail.com> - 2012-09-08 21:21 +1000
      Re: Accessing dll Helpful person <rrllff@yahoo.com> - 2012-09-06 09:46 -0700
        Re: Accessing dll Jerry Hill <malaclypse2@gmail.com> - 2012-09-06 12:58 -0400
          Re: Accessing dll Helpful person <rrllff@yahoo.com> - 2012-09-06 10:10 -0700
        Re: Accessing dll MRAB <python@mrabarnett.plus.com> - 2012-09-06 18:17 +0100
    Re: Accessing dll Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-09-06 17:28 +0200
    Re: Accessing dll Tim Williams <tjandacw@cox.net> - 2012-09-06 13:21 -0700
      Re: Accessing dll Tim Williams <tjandacw@cox.net> - 2012-09-06 13:27 -0700

#28608 — Accessing dll

I am a complete novice to Python.  I wish to access a dll that has
been written to be compatible with C and VB6.  I have been told that
after running Python I should enter  "from ctypes import *" which
allows Python to recognize the dll structure.  I have placed the dll
into my active directory (if that's the correct word, one on my path)
for simplification.

I tried:   "import name.dll" but this just gave me an error telling me
that there was no such module.

Can someone please help?

Richard

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#28610

On Thu, Sep 6, 2012 at 11:07 AM, Helpful person <rrllff@yahoo.com> wrote:
> I am a complete novice to Python.  I wish to access a dll that has
> been written to be compatible with C and VB6.  I have been told that
> after running Python I should enter  "from ctypes import *" which
> allows Python to recognize the dll structure.  I have placed the dll
> into my active directory (if that's the correct word, one on my path)
> for simplification.
>
> I tried:   "import name.dll" but this just gave me an error telling me
> that there was no such module.
>
> Can someone please help?

You should start by reading the ctypes documentation, here:
http://docs.python.org/library/ctypes.html .  It has a lot of examples
that ought to get you started.

When you run into more specific problems, you're going to have to
provide a lot more information before we can help you, including the
specific documentation of the DLL you're trying to wrap, your
platform, and python version.  If you are not permitted to share those
things, we may not be able to give you much help.  Ctypes is very
specific to the actual library you are accessing, and requires that
you understand the requirements of the underlying DLL.

-- 
Jerry

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#28612

On Sep 6, 8:30 am, Jerry Hill <malaclyp...@gmail.com> wrote:
> You should start by reading the ctypes documentation, here:http://docs.python.org/library/ctypes.html.  It has a lot of examples
> that ought to get you started.
>
> When you run into more specific problems, you're going to have to
> provide a lot more information before we can help you, including the
> specific documentation of the DLL you're trying to wrap, your
> platform, and python version.  If you are not permitted to share those
> things, we may not be able to give you much help.  Ctypes is very
> specific to the actual library you are accessing, and requires that
> you understand the requirements of the underlying DLL.
>
> --
> Jerry

Thanks Jerry, I'll read the reference you posted.  Unfortunately I
know almost nothing about the dll and Python is loaded in some strange
framework.

I'll post back after a thorough read about Ctypes.

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#28614

FYI

My Python version is 2.5.4

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#28683

On Fri, Sep 7, 2012 at 1:44 AM, Helpful person <rrllff@yahoo.com> wrote:
> FYI
>
> My Python version is 2.5.4

You may wish to upgrade, that's quite an old version. Unless
something's binding you to version 2.x, I would strongly recommend
migrating to 3.2 or 3.3.

ChrisA

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#28698

On Sep 7, 5:16 am, Chris Angelico <ros...@gmail.com> wrote:
> On Fri, Sep 7, 2012 at 1:44 AM, Helpful person <rrl...@yahoo.com> wrote:
> > FYI
>
> > My Python version is 2.5.4
>
> You may wish to upgrade, that's quite an old version. Unless
> something's binding you to version 2.x, I would strongly recommend
> migrating to 3.2 or 3.3.
>
> ChrisA

Upgrading is not possible due to the large number of programs using
the early version.

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#28719

On Sat, Sep 8, 2012 at 3:27 AM, Helpful person <rrllff@yahoo.com> wrote:
> On Sep 7, 5:16 am, Chris Angelico <ros...@gmail.com> wrote:
>> On Fri, Sep 7, 2012 at 1:44 AM, Helpful person <rrl...@yahoo.com> wrote:
>> > FYI
>>
>> > My Python version is 2.5.4
>>
>> You may wish to upgrade, that's quite an old version. Unless
>> something's binding you to version 2.x, I would strongly recommend
>> migrating to 3.2 or 3.3.
>>
>> ChrisA
>
> Upgrading is not possible due to the large number of programs using
> the early version.

Sure. At least you've considered it. :) Do look into moving up to 2.7,
at least, though. And of course, you can have multiple Pythons
installed simultaneously, allowing you to migrate only when you're
ready.

ChrisA

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#28617

On Sep 6, 8:30 am, Jerry Hill <malaclyp...@gmail.com> wrote:
>
> You should start by reading the ctypes documentation, here:http://docs.python.org/library/ctypes.html.  It has a lot of examples
> that ought to get you started.
>

The reference might help if I could get Python to recognize the dll as
a module.

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#28618

On Thu, Sep 6, 2012 at 12:46 PM, Helpful person <rrllff@yahoo.com> wrote:
> The reference might help if I could get Python to recognize the dll as
> a module.

That's never going to happen.  It's a DLL, not a python module.  I
think the documentation lays that out pretty explicitly.  Have you
experimented with the very first bit of example code in the
documentation?  What do you get if you do the following at the
interactive interpreter?

>>> from ctypes import *
>>> print windll.<insert your dll name here, without the .dll extension>


-- 
Jerry

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#28619

On Sep 6, 9:58 am, Jerry Hill <malaclyp...@gmail.com> wrote:
What do you get if you do the following at the
> interactive interpreter?
>
> >>> from ctypes import *
> >>> print windll.<insert your dll name here, without the .dll extension>
>
> --
> Jerry

I get:

<WinDLL '<my dll name without the dll extension> , handle 410000 at
2ace070>

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#28620

On 06/09/2012 17:58, Jerry Hill wrote:
> On Thu, Sep 6, 2012 at 12:46 PM, Helpful person <rrllff@yahoo.com> wrote:
>> The reference might help if I could get Python to recognize the dll as
>> a module.
>
> That's never going to happen.  It's a DLL, not a python module.  I
> think the documentation lays that out pretty explicitly.  Have you
> experimented with the very first bit of example code in the
> documentation?  What do you get if you do the following at the
> interactive interpreter?
>
>>>> from ctypes import *
>>>> print windll.<insert your dll name here, without the .dll extension>
>
Or this:

 >>> import ctypes
 >>> dll_path = ...
 >>> libc = ctypes.CDLL(dll_path)
 >>> dir(libc)

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#28616

Am 06.09.2012 17:07, schrieb Helpful person:
> I am a complete novice to Python.

Welcome!

> I wish to access a dll that has
> been written to be compatible with C and VB6.  I have been told that
> after running Python I should enter  "from ctypes import *" which
> allows Python to recognize the dll structure.  I have placed the dll
> into my active directory (if that's the correct word, one on my path)
> for simplification.

Using ctypes, you can indeed load DLLs. Take a look at 
http://docs.python.org, which includes the documentation for the ctypes 
module but also general documentation and tutorials, which should be a 
starting point for you.

> I tried:   "import name.dll" but this just gave me an error telling me
> that there was no such module.

Like in VB or C, things are not that easy. You will always have to write 
some code that informs Python about the names and parameters of the 
functions in that DLL.

Good luck!

Uli

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#28635

On Thursday, September 6, 2012 11:07:07 AM UTC-4, Helpful person wrote:
> I am a complete novice to Python.  I wish to access a dll that has
> 
> been written to be compatible with C and VB6.  I have been told that
> 
> after running Python I should enter  "from ctypes import *" which
> 
> allows Python to recognize the dll structure.  I have placed the dll
> 
> into my active directory (if that's the correct word, one on my path)
> 
> for simplification.
> 
> 
> 
> I tried:   "import name.dll" but this just gave me an error telling me
> 
> that there was no such module.
> 
> 
> 
> Can someone please help?
> 
> 
> 
> Richard

I'm new to using the ctypes module also, but what I did to find the library was I appended the location of the dll to my PATH like so: (this is Windows)

pth = os.environ['path'].split(';')
pth.append(os.path.join(os.environ['userprofile'],'My Documents','DLLs'))
os.environ['path'] = ';'.join(pth)

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#28638

On Thursday, September 6, 2012 4:21:56 PM UTC-4, Tim Williams wrote:
> On Thursday, September 6, 2012 11:07:07 AM UTC-4, Helpful person wrote:
> 
> > I am a complete novice to Python.  I wish to access a dll that has
> 
> > 
> 
> > been written to be compatible with C and VB6.  I have been told that
> 
> > 
> 
> > after running Python I should enter  "from ctypes import *" which
> 
> > 
> 
> > allows Python to recognize the dll structure.  I have placed the dll
> 
> > 
> 
> > into my active directory (if that's the correct word, one on my path)
> 
> > 
> 
> > for simplification.
> 
> > 
> 
> > 
> 
> > 
> 
> > I tried:   "import name.dll" but this just gave me an error telling me
> 
> > 
> 
> > that there was no such module.
> 
> > 
> 
> > 
> 
> > 
> 
> > Can someone please help?
> 
> > 
> 
> > 
> 
> > 
> 
> > Richard
> 
> 
> 
> I'm new to using the ctypes module also, but what I did to find the library was I appended the location of the dll to my PATH like so: (this is Windows)
> 
> 
> 
> pth = os.environ['path'].split(';')
> 
> pth.append(os.path.join(os.environ['userprofile'],'My Documents','DLLs'))
> 
> os.environ['path'] = ';'.join(pth)

I should have also mentioned to look at LoadLibrary in the ctypes module. e.g. 

mylib=cdll.LoadLibrary('mylib.dll')

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