When does a binary extension gets the file extension '.pyd' and when is it '.so'

[Fredrik Lundh]

llothar wrote:

> On windows everything is '.pyd' but there seems to be two ways to get
> this on unix?

If you attempt to import the module "spam" on Windows, Python looks for 
"spam.dll" and "spam.pyd" (in addition to "spam.py/spam.pyw/spam.pyc" etc)

On most Unix platforms, Python looks for "spam.so" and "spammodule.so".

You can check what suffixes a given Python version uses via the "imp" 
module:

     >>> import imp
     >>> imp.get_suffixes()

To see *where* Python is looking as well, use the "-vv" flag:

     $ python -vv -c "import spam"
     ...
     # trying spam.so
     # trying spammodule.so
     # trying spam.py
     # trying spam.pyc
     ... etc

(-vv prints loads of stuff, so you may want to use "grep" to filter out 
the stuff you're interested in:

     $ python -vv -c "import spam" 2>&1 | grep spam

or, under Windows:

     > python -vv -c "import spam" 2> out.txt
     > findstr spam out.txt

)

> Why and what is the rule?

If you want Python to be able to import your binary extension, make sure 
to use a name it looks for.

</F>