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From: Michael Felt <michael@felt.demon.nl>
Newsgroups: comp.lang.python
Subject: Re: (Initial) Questions about sysconfig.*
Date: Fri, 04 Mar 2016 14:10:12 +0100
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Thanks for the quick reply. My mailer lost it (rather remembered it 
originiated as a reply to something else, and stored it there) - :)

I would reply between the text below - but, mainly thanks for showing 
the use of 'inspect' - will be extremely handy as I learn enough to make 
a (local) patch.

Michael

p.s. the >>> prompts make it look very colorful in my mail program!

On 2016-03-04 11:22, Peter Otten wrote:
> Michael Felt wrote:
>
>> First, a simple one:
>>
>> sysconfig.is_python_build()
>>
>>       Return True if the current Python installation was built from source.
>>
>>>>>   sysconfig.is_python_build()
>> False
>>
>> Now, not earth shattering, but I did build this from source - so can
>> someone help me with understanding why Python says no?
> Looking into the source of a self-compilee Python version:
>
> $ python3.6
> Python 3.6.0a0 (default:c092148a1b55+, Mar  1 2016, 15:26:05)
> [GCC 4.8.4] on linux
> Type "help", "copyright", "credits" or "license" for more information.
>>>> import sysconfig, inspect
>>>> print(inspect.getsource(sysconfig.is_python_build))
> def is_python_build(check_home=False):
>      if check_home and _sys_home:
>          return _is_python_source_dir(_sys_home)
>      return _is_python_source_dir(_PROJECT_BASE)
>
>>>> print(inspect.getsource(sysconfig._is_python_source_dir))
> def _is_python_source_dir(d):
>      for fn in ("Setup.dist", "Setup.local"):
>          if os.path.isfile(os.path.join(d, "Modules", fn)):
>              return True
>      return False
>
>>>> sysconfig._PROJECT_BASE
> '/usr/local/bin'
>
> So this effectively looks for the file /usr/local/bin/Modules/Setup.dist
> or /usr/local/bin/Modules/Setup.local which of course fails. You have to
> invoke the interpreter in the directory where it was built:
>
> $ /wherever/you/unpacked/and/compiled/python
> Python 3.6.0a0 (default:c092148a1b55+, Mar  1 2016, 15:26:05)
> [GCC 4.8.4] on linux
> Type "help", "copyright", "credits" or "license" for more information.
>>>> import sysconfig
>>>> sysconfig.is_python_build()
> True
>
>> And a last question (more about the configure phase I expect)
>>
>> ...() returns, among other things:
>>
>> 'LIBRARY_OBJS': '\\',
>> 'MODULE_OBJS': '\\',
>> 'PARSER_HEADERS': '\\',
>> 'PGENSRCS': '\\ \\',
>> 'PYTHON_OBJS': '\\',
>> 'QUICKTESTOPTS': '-l -x test_subprocess test_io test_lib2to3 \\',
>>
>> 'SHLIB_EXT': '".so"',
>>
>> Why are any of these using '\\' for anything on 'posix'?
> Is that data actually used anywhere? I suspect this is a parsing mishap and
> these are actually line continuation indicators. In the Makefile I find (e.
> g.)
>
> PYTHON_OBJS=	\
> 		Python/_warnings.o \
> 		Python/Python-ast.o \
> 		Python/asdl.o \
> [snip]
>
>
>