[Scons-dev] Python 3 issue

[RW]

Just to comment on this one
it looks like others have had the same problem as well
https://github.com/datafolklabs/cement/issues/386
https://stackoverflow.com/questions/38802908/importing-module-with-current-directory-imports

I suspect this might be a wider issue with python not supporting relative
imports when using exec_module from importlib

To simplify the problem a bit without hacking scons I tried creating a
small lump of code within site_scons\site_tools (of the example code posted
so far) to see if there's a workaround. Not managed to find one so far


test1.py
```
import os
import importlib.util

#import relative

def path_import(absolute_path):
   '''implementation taken from
https://docs.python.org/3/library/importlib.html#importing-a-source-file-directly'
''
   spec = importlib.util.spec_from_file_location(absolute_path,
absolute_path)
   module = importlib.util.module_from_spec(spec)
   spec.loader.exec_module(module)
   return module

def main():
    root = os.path.abspath(os.path.dirname(os.path.realpath(__file__)))
    modpath = os.path.join(root, 'relative', '__init__.py')
    print(modpath)
    path_import(modpath)

if __name__ == '__main__':
    main()
```


On 23 June 2017 at 19:03, Bill Deegan <bill at baddogconsulting.com> wrote:

> O.k so relative imports should work with both py3 and py2, but likely our
> tool import logic is breaking it with py3.
> (the logic is different for py3 https://bitbucket.org/scons/scons/src/
> e2d9abca56a519930e5846a3634c85074fcbba47/src/engine/SCons/
> Tool/__init__.py?at=default&fileviewer=file-view-default#__init__.py-164)
>
>
> Can we live with absolute imports until we resolve the issue?
>
> -Bill
>
> On Fri, Jun 23, 2017 at 10:53 AM, Bill Deegan <bill at baddogconsulting.com>
> wrote:
>
>> This change:
>> https://bitbucket.org/bdbaddog/scons-russel-example/commits/
>> 48899a710f9afbec891307addd6ae5b9c08d53c9?at=master
>>
>> Will make it work in py2 and py3.
>>
>> Any reason we can't live with that?
>>
>> -Bill
>>
>> On Fri, Jun 23, 2017 at 10:38 AM, Bill Deegan <bill at baddogconsulting.com>
>> wrote:
>>
>>> Russel,
>>>
>>> I've created a git repo in bitbucket to facilitate talking about this
>>> issue.
>>>
>>> https://bitbucket.org/bdbaddog/scons-russel-example
>>>
>>> And given you permissions.
>>> The second commit should be the same as your zip file.
>>> Going forward, it's far easier to create a throwaway repo and share it
>>> than to pass zip files back and forth..
>>>
>>> -Bill
>>>
>>>
>>> On Fri, Jun 23, 2017 at 7:14 AM, Russel Winder <russel at winder.org.uk>
>>> wrote:
>>>
>>>> Python 3 changed the way imports worked, absolute imports became the
>>>> norm. However relative imports were retain via extra syntax. This has,
>>>> I believe been backported to Python 2.7.
>>>>
>>>> The summary of the situation is that to enable tools as packages as
>>>> well as tools as modules, you have to use relative imports of generate
>>>> and exists in __init__.py. This used to work fine. A very minor change
>>>> of syntax means it all still works on Python 2. However on Python 3
>>>> something weird happens. This is a SCons thing, because if you do the
>>>> equivalent it pure Python is works fine with either 2 or 3.
>>>>
>>>> So given the attached project:
>>>>
>>>> > python /home/users/russel/Repositories/Mercurial/Forks/SCons/src/sc
>>>> ript/scons.py
>>>> scons: Reading SConscript files ...
>>>> __init__ loaded.
>>>> generate called.
>>>> scons: done reading SConscript files.
>>>> scons: Building targets ...
>>>> scons: `.' is up to date.
>>>> scons: done building targets.
>>>> 546 lavaine:~/Progs/OddsByLanguage/SCons/RelativeImports
>>>> |> python3 /home/users/russel/Repositories/Mercurial/Forks/SCons/src/sc
>>>> ript/scons.py
>>>> scons: Reading SConscript files ...
>>>> SystemError: Parent module 'relative' not loaded, cannot perform
>>>> relative import:
>>>>   File "/home/users/russel/Progs/OddsByLanguage/SCons/RelativeImports/SConstruct",
>>>> line 1:
>>>>     env = Environment(tools=['relative'])
>>>>   File "/home/users/russel/Repositories/Mercurial/Forks/SCons/src/engine/SCons/Environment.py",
>>>> line 982:
>>>>     apply_tools(self, tools, toolpath)
>>>>   File "/home/users/russel/Repositories/Mercurial/Forks/SCons/src/engine/SCons/Environment.py",
>>>> line 107:
>>>>     env.Tool(tool)
>>>>   File "/home/users/russel/Repositories/Mercurial/Forks/SCons/src/engine/SCons/Environment.py",
>>>> line 1788:
>>>>     tool = SCons.Tool.Tool(tool, toolpath, **kw)
>>>>   File "/home/users/russel/Repositories/Mercurial/Forks/SCons/src/engine/SCons/Tool/__init__.py",
>>>> line 115:
>>>>     module = self._tool_module()
>>>>   File "/home/users/russel/Repositories/Mercurial/Forks/SCons/src/engine/SCons/Tool/__init__.py",
>>>> line 228:
>>>>     spec.loader.exec_module(module)
>>>>   File "<frozen importlib._bootstrap_external>", line 697:
>>>>
>>>>   File "<frozen importlib._bootstrap>", line 222:
>>>>
>>>>   File "/home/users/russel/Progs/OddsByLanguage/SCons/RelativeImpor
>>>> ts/site_scons/site_tools/relative/__init__.py", line 3:
>>>>     from .thingy import generate, exists
>>>>
>>>>
>>>>
>>>> --
>>>> Russel.
>>>> ============================================================
>>>> =================
>>>> Dr Russel Winder      t: +44 20 7585 2200   voip:
>>>> sip:russel.winder at ekiga.net
>>>> 41 Buckmaster Road    m: +44 7770 465 077   xmpp: russel at winder.org.uk
>>>> London SW11 1EN, UK   w: www.russel.org.uk  skype: russel_winder
>>>> _______________________________________________
>>>> Scons-dev mailing list
>>>> Scons-dev at scons.org
>>>> https://pairlist2.pair.net/mailman/listinfo/scons-dev
>>>>
>>>>
>>>
>>
>
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