[Python-Dev] Draft: PEP for imports

[Chris Reedy]

Armin Rigo wrote:

>  import neatTricks in "/home/guido/lib/python"      # no package
>  import package.module in "/home/guido/lib/python"  # package
>  import foo in "."                                  # relative import
>  from neatTricks in "../cmds" import a, b, c
>  s=os.path.join("some", "where"); import foo in s   # expression path
>
>where the semantics would be to search sys.path if and only if no 'in' clause
>is specified.  ('in' doesn't sound quite right...)
>
Armin -

Thinking about the semantics of the above, including corner cases, I 
find myself wanting to make the semantics of:

  <some_kind_of_import_statement> in "<path>"

to be equivalent to:

  sys.path.insert(0, "<path>")
  <some_kind_of_import_statement>
  del sys.path[0] # assuming the import doesn't modify sys.path

That doesn't seem to be quite equivalent to what you've proposed. On the 
other hand, that seems to provide at least semi-reasonable answers to 
questions about what happens to sys.modules, what happens if 
sys.modules['package'] is defined when importing package.module, what's 
the correct search path when a module being imported does an import, etc.

Having said that, that makes me feel negatively about the proposal, 
since you could do it yourself directly.

  Chris