diff options
Diffstat (limited to 'Doc/reference')
| -rw-r--r-- | Doc/reference/executionmodel.rst | 4 | ||||
| -rw-r--r-- | Doc/reference/expressions.rst | 35 |
2 files changed, 28 insertions, 11 deletions
diff --git a/Doc/reference/executionmodel.rst b/Doc/reference/executionmodel.rst index 90791d2..b4c29b1 100644 --- a/Doc/reference/executionmodel.rst +++ b/Doc/reference/executionmodel.rst @@ -120,7 +120,7 @@ namespace is searched. The global statement must precede all uses of the name. .. index:: pair: restricted; execution -The built-in namespace associated with the execution of a code block is actually +The builtins namespace associated with the execution of a code block is actually found by looking up the name ``__builtins__`` in its global namespace; this should be a dictionary or a module (in the latter case the module's dictionary is used). By default, when in the :mod:`__main__` module, ``__builtins__`` is @@ -132,7 +132,7 @@ weak form of restricted execution. .. impl-detail:: Users should not touch ``__builtins__``; it is strictly an implementation - detail. Users wanting to override values in the built-in namespace should + detail. Users wanting to override values in the builtins namespace should :keyword:`import` the :mod:`builtins` module and modify its attributes appropriately. diff --git a/Doc/reference/expressions.rst b/Doc/reference/expressions.rst index d074ebb..d0acd20 100644 --- a/Doc/reference/expressions.rst +++ b/Doc/reference/expressions.rst @@ -1113,12 +1113,7 @@ Boolean operations pair: Conditional; expression pair: Boolean; operation -Boolean operations have the lowest priority of all Python operations: - .. productionlist:: - expression: `conditional_expression` | `lambda_form` - expression_nocond: `or_test` | `lambda_form_nocond` - conditional_expression: `or_test` ["if" `or_test` "else" `expression`] or_test: `and_test` | `or_test` "or" `and_test` and_test: `not_test` | `and_test` "and" `not_test` not_test: `comparison` | "not" `not_test` @@ -1135,10 +1130,6 @@ truth value by providing a :meth:`__bool__` method. The operator :keyword:`not` yields ``True`` if its argument is false, ``False`` otherwise. -The expression ``x if C else y`` first evaluates *C* (*not* *x*); if *C* is -true, *x* is evaluated and its value is returned; otherwise, *y* is evaluated -and its value is returned. - .. index:: operator: and The expression ``x and y`` first evaluates *x*; if *x* is false, its value is @@ -1158,6 +1149,30 @@ not bother to return a value of the same type as its argument, so e.g., ``not 'foo'`` yields ``False``, not ``''``.) +Conditional Expressions +======================= + +.. versionadded:: 2.5 + +.. index:: + pair: conditional; expression + pair: ternary; operator + +.. productionlist:: + conditional_expression: `or_test` ["if" `or_test` "else" `expression`] + expression: `conditional_expression` | `lambda_form` + expression_nocond: `or_test` | `lambda_form_nocond` + +Conditional expressions (sometimes called a "ternary operator") have the lowest +priority of all Python operations. + +The expression ``x if C else y`` first evaluates the condition, *C* (*not* *x*); +if *C* is true, *x* is evaluated and its value is returned; otherwise, *y* is +evaluated and its value is returned. + +See :pep:`308` for more details about conditional expressions. + + .. _lambdas: .. _lambda: @@ -1252,6 +1267,8 @@ groups from right to left). +===============================================+=====================================+ | :keyword:`lambda` | Lambda expression | +-----------------------------------------------+-------------------------------------+ +| :keyword:`if` -- :keyword:`else` | Conditional expression | ++-----------------------------------------------+-------------------------------------+ | :keyword:`or` | Boolean OR | +-----------------------------------------------+-------------------------------------+ | :keyword:`and` | Boolean AND | |