On 4/21/06, Thomas Wouters <[EMAIL PROTECTED]> wrote: > > On 4/21/06, guido.van.rossum <python-3000-checkins@python.org> wrote: > > The hardest part was fixing two mutual recursive imports; > > somehow changing "import foo" into "from . import foo" where > > foo and bar import each other AND both are imported from __init__.py > caused things to break. Bah. > > Hm, this is possibly a flaw in the explicit relative import mechanism. > Normal circular imports work because a module object is stuffed into > sys.modules before any code for the module is executed, so the next 'import' > of that module just finds the half-loaded module object. I guess 'from . > import name' really looks at the package contents, though, and there, the > module isn't stored until it's done loading. I'm not sure why it raises a > 'cannot import name' exception instead of recursing into a spiral of death, > but I guess that's a good thing. :)
That's what I thought. But I believe I reproduced it in 2.4 as well. I'm not 100% sure but I've got a feeling that the situation is actually due to these imports happening *while __init__ is loading*. When P is a package and M is a module, "from P import M" seems to first check that sys.modules["P.M"] exists, but then it somehow asks for P.M instead for sys.modules["P.M"]. At least that's how I cam up with the fix (which sets P.M from inside M) and the fix made the problem go away. > Should this be fixed, or is it an esoteric enough case that I shouldn't > bother? I do think it ought to be fixed, and in 2.5 as well. -- --Guido van Rossum (home page: http://www.python.org/~guido/) _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
