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Diffstat (limited to 'Doc/reference/expressions.rst')
| -rw-r--r-- | Doc/reference/expressions.rst | 51 |
1 files changed, 40 insertions, 11 deletions
diff --git a/Doc/reference/expressions.rst b/Doc/reference/expressions.rst index 95ece0e..cfada6e 100644 --- a/Doc/reference/expressions.rst +++ b/Doc/reference/expressions.rst @@ -83,18 +83,47 @@ exception. pair: name; mangling pair: private; names -**Private name mangling:** When an identifier that textually occurs in a class -definition begins with two or more underscore characters and does not end in two -or more underscores, it is considered a :dfn:`private name` of that class. -Private names are transformed to a longer form before code is generated for -them. The transformation inserts the class name, with leading underscores -removed and a single underscore inserted, in front of the name. For example, -the identifier ``__spam`` occurring in a class named ``Ham`` will be transformed -to ``_Ham__spam``. This transformation is independent of the syntactical -context in which the identifier is used. If the transformed name is extremely -long (longer than 255 characters), implementation defined truncation may happen. -If the class name consists only of underscores, no transformation is done. +Private name mangling +^^^^^^^^^^^^^^^^^^^^^ +When an identifier that textually occurs in a class definition begins with two +or more underscore characters and does not end in two or more underscores, it +is considered a :dfn:`private name` of that class. + +.. seealso:: + + The :ref:`class specifications <class>`. + +More precisely, private names are transformed to a longer form before code is +generated for them. If the transformed name is longer than 255 characters, +implementation-defined truncation may happen. + +The transformation is independent of the syntactical context in which the +identifier is used but only the following private identifiers are mangled: + +- Any name used as the name of a variable that is assigned or read or any + name of an attribute being accessed. + + The ``__name__`` attribute of nested functions, classes, and type aliases + is however not mangled. + +- The name of imported modules, e.g., ``__spam`` in ``import __spam``. + If the module is part of a package (i.e., its name contains a dot), + the name is *not* mangled, e.g., the ``__foo`` in ``import __foo.bar`` + is not mangled. + +- The name of an imported member, e.g., ``__f`` in ``from spam import __f``. + +The transformation rule is defined as follows: + +- The class name, with leading underscores removed and a single leading + underscore inserted, is inserted in front of the identifier, e.g., the + identifier ``__spam`` occurring in a class named ``Foo``, ``_Foo`` or + ``__Foo`` is transformed to ``_Foo__spam``. + +- If the class name consists only of underscores, the transformation is the + identity, e.g., the identifier ``__spam`` occurring in a class named ``_`` + or ``__`` is left as is. .. _atom-literals: |