Run-time type checker for Python
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This library provides run-time type checking for functions defined with
PEP 484 <https://www.python.org/dev/peps/pep-0484/>_ argument (and return) type
annotations, and any arbitrary objects. It can be used together with static type
checkers as an additional layer of type safety, to catch type violations that could only
be detected at run time.
Two principal ways to do type checking are provided:
#. The check_type function:
like isinstance(), but supports arbitrary type annotations (within limits)
can be used as a cast() replacement, but with actual checking of the value
#. Code instrumentation:
entire modules, or individual functions (via @typechecked) are recompiled, with
type checking code injected into them
automatically checks function arguments, return values and assignments to annotated local variables
for generator functions (regular and async), checks yield and send values
requires the original source code of the instrumented module(s) to be accessible
Two options are provided for code instrumentation:
#. the @typechecked function:
can be applied to functions individually
#. the import hook (typeguard.install_import_hook()):
automatically instruments targeted modules on import
no manual code changes required in the target modules
requires the import hook to be installed before the targeted modules are imported
may clash with other import hooks
See the documentation_ for further information.
.. _documentation: https://typeguard.readthedocs.io/en/latest/