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Diffstat (limited to 'Doc/reference/datamodel.rst')
| -rw-r--r-- | Doc/reference/datamodel.rst | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst index 1aef266..82106a4 100644 --- a/Doc/reference/datamodel.rst +++ b/Doc/reference/datamodel.rst @@ -3044,10 +3044,12 @@ left undefined. (``+=``, ``-=``, ``*=``, ``@=``, ``/=``, ``//=``, ``%=``, ``**=``, ``<<=``, ``>>=``, ``&=``, ``^=``, ``|=``). These methods should attempt to do the operation in-place (modifying *self*) and return the result (which could be, - but does not have to be, *self*). If a specific method is not defined, the + but does not have to be, *self*). If a specific method is not defined, or if + that method returns :data:`NotImplemented`, the augmented assignment falls back to the normal methods. For instance, if *x* is an instance of a class with an :meth:`__iadd__` method, ``x += y`` is - equivalent to ``x = x.__iadd__(y)`` . Otherwise, ``x.__add__(y)`` and + equivalent to ``x = x.__iadd__(y)`` . If :meth:`__iadd__` does not exist, or if ``x.__iadd__(y)`` + returns :data:`!NotImplemented`, ``x.__add__(y)`` and ``y.__radd__(x)`` are considered, as with the evaluation of ``x + y``. In certain situations, augmented assignment can result in unexpected errors (see :ref:`faq-augmented-assignment-tuple-error`), but this behavior is in fact |