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Diffstat (limited to 'Doc/tutorial/classes.rst')
| -rw-r--r-- | Doc/tutorial/classes.rst | 25 |
1 files changed, 14 insertions, 11 deletions
diff --git a/Doc/tutorial/classes.rst b/Doc/tutorial/classes.rst index 696860d..8c45d1a 100644 --- a/Doc/tutorial/classes.rst +++ b/Doc/tutorial/classes.rst @@ -473,8 +473,8 @@ scope.) Multiple Inheritance -------------------- -Python supports a limited form of multiple inheritance as well. A class -definition with multiple base classes looks like this:: +Python supports a form of multiple inheritance as well. A class definition with +multiple base classes looks like this:: class DerivedClassName(Base1, Base2, Base3): <statement-1> @@ -483,15 +483,18 @@ definition with multiple base classes looks like this:: . <statement-N> -Formerly, the only rule was depth-first, left-to-right. Thus, if an attribute -was not found in :class:`DerivedClassName`, it was searched in :class:`Base1`, -then (recursively) in the base classes of :class:`Base1`, and only if it was not -found there, it was searched in :class:`Base2`, and so on. - -In the meantime, the method resolution order changes dynamically to support -cooperative calls to :func:`super`. This approach is known in some other -multiple-inheritance languages as call-next-method and is more powerful than the -super call found in single-inheritance languages. +For most purposes, in the simplest cases, you can think of the search for +attributes inherited from a parent class as depth-first, left-to-right, not +searching twice in the same class where there is an overlap in the hierarchy. +Thus, if an attribute is not found in :class:`DerivedClassName`, it is searched +for in :class:`Base1`, then (recursively) in the base classes of :class:`Base1`, +and if it was not found there, it was searched for in :class:`Base2`, and so on. + +In fact, it is slightly more complex than that; the method resolution order +changes dynamically to support cooperative calls to :func:`super`. This +approach is known in some other multiple-inheritance languages as +call-next-method and is more powerful than the super call found in +single-inheritance languages. Dynamic ordering is necessary because all cases of multiple inheritance exhibit one or more diamond relationships (where one at least one of the parent classes |