Allow modules to stub themselves out

[flying-sheep]

I currently rely on a hack to enable flit to get the version of a module with no dependencies installed.

This patch would allow me to just use if not os.environ.get('FLIT_GETTING_VERSION'): ...

pkg/_metadata.py

import traceback
from get_version import get_version
__version__ = get_version(__file__.replace('_metadata', '__init__'))

def within_flit():
    import traceback
    for frame in traceback.extract_stack():
        if frame.name == 'get_docstring_and_version_via_import':
            return True
    return False

pkg/__init__.py:

"""Your package docstring"""
	   
from ._metadata import __version__, within_flit
	   
if not within_flit():
    from .subpackage import thing