diff options
Diffstat (limited to 'Doc')
| -rw-r--r-- | Doc/library/typing.rst | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/Doc/library/typing.rst b/Doc/library/typing.rst index 60f49d7029..00d74f7dc3 100644 --- a/Doc/library/typing.rst +++ b/Doc/library/typing.rst @@ -2438,15 +2438,16 @@ Functions and decorators Ask a static type checker to confirm that *val* has an inferred type of *typ*. - When the type checker encounters a call to ``assert_type()``, it + At runtime this does nothing: it returns the first argument unchanged with no + checks or side effects, no matter the actual type of the argument. + + When a static type checker encounters a call to ``assert_type()``, it emits an error if the value is not of the specified type:: def greet(name: str) -> None: assert_type(name, str) # OK, inferred type of `name` is `str` assert_type(name, int) # type checker error - At runtime this returns the first argument unchanged with no side effects. - This function is useful for ensuring the type checker's understanding of a script is in line with the developer's intentions:: |