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Re: 2.7 source import in python 3.x

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  Re: 2.7 source import in python 3.x Peter Otten <__peter__@web.de> - 2016-04-04 13:15 +0200

#106432 — Re: 2.7 source import in python 3.x

Robin Becker wrote:

> A user points out that this code in reportlab uses the now deprecated imp
> module
> 
> def _fake_import(fn,name):
>      if os.path.isfile(fn):
>          import imp
>          with open(fn,'rb') as f:
>              imp.load_source(name,fn,f)
> 
> and suggests I use importlib SourceFileLoader. Is there anything wrong
> with this code (only for use in python 3.x)
> 
> 
> def _fake_import(fn,name):
>      from importlib import machinery
>      m = machinery.SourceFileLoader(name,fn)
>      try:
>          return m.load_module(name)
>      except FileNotFoundError:
>          raise ImportError('file %s not found' % ascii(fn))
> 
> the newer import machinery seems particularly complex so I'm not at all
> sure this does what I intend even though it seems to work.

Seems like Python is one step ahead in the deprecation race. Quoting

https://docs.python.org/dev/library/importlib.html#importlib.machinery.SourceFileLoader.load_module

"""
load_module(name=None)
Concrete implementation of importlib.abc.Loader.load_module() where 
specifying the name of the module to load is optional.

Deprecated since version 3.6: Use importlib.abc.Loader.exec_module() 
instead.
"""

In the example section they have (for 3.4 and above)

spec = importlib.util.spec_from_file_location(module_name, file_path)
module = importlib.util.module_from_spec(spec)
spec.loader.exec_module(module)

The importlib with all its factories is a bit intimidating; perhaps it's 
best to stick with imp.load_source() and wait for some simple helper 
functions to appear...

> The original function is only used once like this
> 
>> try:
>>     
_fake_import(os.path.expanduser(os.path.join('~','.reportlab_mods')),'reportlab_mods')
>> except (ImportError,KeyError):
>>     pass
> 
> and is intended to allow per user actions in a config file when reportlab
> is imported.
> 

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