RESOLVED FIXED 47884
should we allow multiple inheritance in python code in webkit? 
https://bugs.webkit.org/show_bug.cgi?id=47884
Summary should we allow multiple inheritance in python code in webkit?
Dirk Pranke
Reported 2010-10-18 22:54:17 PDT
See bug 47874 for some background ... there are places in the code where using MI would make the code cleaner, like webkitpy/layout_tests/port/{google_chrome,chromium_gpu}.py , where the classes naturally want some sort of diamond and/or mixin behavior, and we resort to unpleasantness in its absence.
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Adam Barth
Comment 1 2010-10-18 22:57:05 PDT
We use multiple inheritance in a bunch of places in webkitpy, mostly int the Mixin pattern.
Adam Barth
Comment 2 2010-10-18 22:57:30 PDT
Actually, also to inherit from "pure virtual" interfaces.
Tony Chang
Comment 3 2010-10-19 09:56:48 PDT
I'm fine with pure virtual interfaces and to a lesser degree, mixin. The proper way to refactor the google_chrome and chromium_gpu ports would be to have delegate classes for specific functionality of a port. For example, having a delegate that provides a few path functions (e.g., baseline search path and path to expectations) and have it be a member variable of Port. This could also be done via mixins, but I think the delegate pattern is more widely used in WebKit code.
Tony Chang
Comment 4 2010-10-19 09:59:07 PDT
To clarify, I think what we want to avoid is a GPU port and a Linux port where we inherit from both to make a Linux GPU port. That would be confusing because you don't know what functions are provided by which base class.
Dirk Pranke
Comment 5 2010-10-21 16:42:16 PDT
I think I will consider this closed as "yes, with caution". Anyone please reopen or comment if you disagree :)
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