diff options
Diffstat (limited to 'Doc/reference')
| -rw-r--r-- | Doc/reference/compound_stmts.rst | 10 | ||||
| -rw-r--r-- | Doc/reference/simple_stmts.rst | 7 |
2 files changed, 12 insertions, 5 deletions
diff --git a/Doc/reference/compound_stmts.rst b/Doc/reference/compound_stmts.rst index 8e68081..96bd9b0 100644 --- a/Doc/reference/compound_stmts.rst +++ b/Doc/reference/compound_stmts.rst @@ -1244,9 +1244,13 @@ following the parameter name. Any parameter may have an annotation, even those ``*identifier`` or ``**identifier``. Functions may have "return" annotation of the form "``-> expression``" after the parameter list. These annotations can be any valid Python expression. The presence of annotations does not change the -semantics of a function. The annotation values are available as string values -in a dictionary keyed by the parameters' names in the :attr:`__annotations__` -attribute of the function object. +semantics of a function. The annotation values are available as values of +a dictionary keyed by the parameters' names in the :attr:`__annotations__` +attribute of the function object. If the ``annotations`` import from +:mod:`__future__` is used, annotations are preserved as strings at runtime which +enables postponed evaluation. Otherwise, they are evaluated when the function +definition is executed. In this case annotations may be evaluated in +a different order than they appear in the source code. .. index:: pair: lambda; expression diff --git a/Doc/reference/simple_stmts.rst b/Doc/reference/simple_stmts.rst index 941b342..3aba270 100644 --- a/Doc/reference/simple_stmts.rst +++ b/Doc/reference/simple_stmts.rst @@ -877,11 +877,14 @@ can appear before a future statement are: * blank lines, and * other future statements. +The only feature that requires using the future statement is +``annotations`` (see :pep:`563`). + All historical features enabled by the future statement are still recognized by Python 3. The list includes ``absolute_import``, ``division``, ``generators``, ``generator_stop``, ``unicode_literals``, -``print_function``, ``nested_scopes``, ``with_statement`` and ``annotations``. -They are all redundant because they are always enabled, and only kept for +``print_function``, ``nested_scopes`` and ``with_statement``. They are +all redundant because they are always enabled, and only kept for backwards compatibility. A future statement is recognized and treated specially at compile time: Changes |