Version history

This library adheres to Semantic Versioning 2.0.

4.4.4 (2026-06-18)

• Fixed IndexError when using @typechecked on more than one function with the same name under certain circumstances (#527)

• Fixed TypeError during type checking when the value to check is a parametrized generic class (#526)

4.4.3 (2025-06-05)

• Fixed @typechecked unable to find the target function or method if it or the containing class had PEP 695 type parameters on them (#500)

• Fixed handling of union types on Python 3.14 (#522)

• Fixed __type_params__ getting lost when a function is instrumented

4.4.2 (2025-02-16)

• Fixed TypeCheckError in unpacking assignment involving properties of a parameter of the function (#506; regression introduced in v4.4.1)

• Fixed display of module name for forward references (#492; PR by @JelleZijlstra)

• Fixed TypeError when using an assignment expression (#510; PR by @JohannesK71083)

• Fixed ValueError: no signature found for builtin when checking against a protocol and a matching attribute in the subject is a built-in function (#504)

4.4.1 (2024-11-03)

• Dropped Python 3.8 support

• Changed the signature of typeguard_ignore() to be compatible with typing.no_type_check() (PR by @jolaf)

• Avoid creating reference cycles when type checking uniontypes and classes

• Fixed checking of variable assignments involving tuple unpacking (#486)

• Fixed TypeError when checking a class against type[Self] (#481)

• Fixed checking of protocols on the class level (against type[SomeProtocol]) (#498)

• Fixed Self checks in instance/class methods that have positional-only arguments

• Fixed explicit checks of PEP 604 unions against types.UnionType (#467)

• Fixed checks against annotations wrapped in NotRequired not being run unless the NotRequired is a forward reference (#454)

4.4.0 (2024-10-27)

• Added proper checking for method signatures in protocol checks (#465)

• Fixed basic support for intersection protocols (#490; PR by @antonagestam)

4.3.0 (2024-05-27)

• Added support for checking against static protocols

• Fixed some compatibility problems when running on Python 3.13 (#460; PR by @JelleZijlstra)

• Fixed test suite incompatibility with pytest 8.2 (#461)

• Fixed pytest plugin crashing on pytest version older than v7.0.0 (even if it’s just present) (#343)

4.2.1 (2023-03-24)

• Fixed missing typing_extensions dependency for Python 3.12 (#444)

• Fixed deprecation warning in the test suite on Python 3.13 (#444)

4.2.0 (2023-03-23)

• Added support for specifying options for the pytest plugin via pytest config files (#440)

• Avoid creating reference cycles when type checking unions (PR by Shantanu)

• Fixed Optional[...] being removed from the AST if it was located within a subscript (#442)

• Fixed TypedDict from typing_extensions not being recognized as one (#443)

• Fixed typing types (dict[str, int], List[str], etc.) not passing checks against type or Type (#432, PR by Yongxin Wang)

• Fixed detection of optional fields (NotRequired[...]) in TypedDict when using forward references (#424)

• Fixed mapping checks against Django’s MultiValueDict (#419)

4.1.5 (2023-09-11)

• Fixed Callable erroneously rejecting a callable that has the requested amount of positional arguments but they have defaults (#400)

• Fixed a regression introduced in v4.1.4 where the elements of Literal got quotes removed from them by the AST transformer (#399)

4.1.4 (2023-09-10)

• Fixed AttributeError where the transformer removed elements from a PEP 604 union (#384)

• Fixed AttributeError: 'Subscript' object has no attribute 'slice' when encountering an annotation with a subscript containing an ignored type (imported within an if TYPE_CHECKING: block) (#397)

• Fixed type checking not being skipped when the target is a union (PEP 604 or typing.Union) where one of the elements is an ignored type (shadowed by an argument, variable assignment or an if TYPE_CHECKING import) (#394, #395)

• Fixed type checking of class instances created in __new__() in cases such as enums where this method is already invoked before the class has finished initializing (#398)

4.1.3 (2023-08-27)

• Dropped Python 3.7 support

• Fixed @typechecked optimization causing compilation of instrumented code to fail when any block was left empty by the AST transformer (eg if or try / except blocks) (#352)

• Fixed placement of injected typeguard imports with respect to __future__ imports and module docstrings (#385)

4.1.2 (2023-08-18)

• Fixed Any being removed from a subscript that still contains other elements (#373)

4.1.1 (2023-08-16)

• Fixed suppress_type_checks() causing annotated variable assignments to always assign None (#380)

4.1.0 (2023-07-30)

• Added support for passing a tuple as expected_type to check_type(), making it more of a drop-in replacement for isinstance() (#371)

• Fixed regression where Literal inside a Union had quotes stripped from its contents, thus typically causing NameError to be raised when run (#372)

4.0.1 (2023-07-27)

• Fixed handling of typing_extensions.Literal on Python 3.8 and 3.9 when typing_extensions>=4.6.0 is installed (#363; PR by Alex Waygood)

• Fixed NameError when generated type checking code references an imported name from a method (#362)

• Fixed docstrings disappearing from instrumented functions (#359)

• Fixed @typechecked failing to instrument functions when there are more than one function within the same scope (#355)

• Fixed frozenset not being checked (#367)

4.0.0 (2023-05-12)

• No changes

4.0.0rc6 (2023-05-07)

• Fixed @typechecked optimization causing compilation of instrumented code to fail when an if block was left empty by the AST transformer (#352)

• Fixed the AST transformer trying to parse the second argument of typing.Annotated as a forward reference (#353)

4.0.0rc5 (2023-05-01)

• Added InstrumentationWarning to the public API

• Changed @typechecked to skip instrumentation in optimized mode, as in typeguard 2.x

• Avoid type checks where the types in question are shadowed by local variables

• Fixed instrumentation using typing.Optional without a subscript when the subscript value was erased due to being an ignored import

• Fixed TypeError: isinstance() arg 2 must be a type or tuple of types when instrumented code tries to check a value against a naked (str, not ForwardRef) forward reference

• Fixed instrumentation using the wrong “self” type in the __new__() method

4.0.0rc4 (2023-04-15)

• Fixed imports guarded by if TYPE_CHECKING: when used with subscripts (SomeType[...]) being replaced with Any[...] instead of just Any

• Fixed instrumentation inadvertently mutating a function’s annotations on Python 3.7 and 3.8

• Fixed Concatenate[...] in Callable parameters causing TypeError to be raised

• Fixed type checks for *args or **kwargs not being suppressed when their types are unusable (guarded by if TYPE_CHECKING: or otherwise)

• Fixed TypeError when checking against a generic NewType

• Don’t try to check types shadowed by argument names (e.g. def foo(x: type, type: str): ...)

• Don’t check against unions where one of the elements is Any

4.0.0rc3 (2023-04-10)

• Fixed typing.Literal subscript contents being evaluated as forward references

• Fixed resolution of forward references in type aliases

4.0.0rc2 (2023-04-08)

• The .pyc files now use a version-based optimization suffix in the file names so as not to cause the interpreter to load potentially faulty/incompatible cached bytecode generated by older versions

• Fixed typed variable positional and keyword arguments causing compilation errors on Python 3.7 and 3.8

• Fixed compilation error when a type annotation contains a type guarded by if TYPE_CHECKING:

4.0.0rc1 (2023-04-02)

• BACKWARD INCOMPATIBLE check_type() no longer uses the global configuration. It now uses the default configuration values, unless overridden with an explicit config argument.

• BACKWARD INCOMPATIBLE Removed CallMemo from the API

• BACKWARD INCOMPATIBLE Required checkers to use the configuration from memo.config, rather than the global configuration

• Added keyword arguments to @typechecked, allowing users to override settings on a per-function basis

• Added support for using suppress_type_checks() as a decorator

• Added support for type checking against nonlocal classes defined within the same parent function as the instrumented function

• Changed instrumentation to statically copy the function annotations to avoid having to look up the function object at run time

• Improved support for avoiding type checks against imports declared in if TYPE_CHECKING: blocks

• Fixed check_type not returning the passed value when checking against Any, or when type checking is being suppressed

• Fixed suppress_type_checks() not ending the suppression if the context block raises an exception

• Fixed checking non-dictionary objects against a TypedDict annotation (PR by Tolker-KU)

3.0.2 (2023-03-22)

• Improved warnings by ensuring that they target user code and not Typeguard internal code

• Fixed warn_on_error() not showing where the type violation actually occurred

• Fixed local assignment to *args or **kwargs being type checked incorrectly

• Fixed TypeError on check_type(..., None)

• Fixed unpacking assignment not working with a starred variable (x, *y = ...) in the target tuple

• Fixed variable multi-assignment (a = b = c = ...) being type checked incorrectly

3.0.1 (2023-03-16)

• Improved the documentation

• Fixed assignment unpacking (a, b = ...) being checked incorrectly

• Fixed @typechecked attempting to instrument wrapper decorators such as @contextmanager when applied to a class

• Fixed py.typed missing from the wheel when not building from a git checkout

3.0.0 (2023-03-15)

• BACKWARD INCOMPATIBLE Dropped the argname, memo, globals and locals arguments from check_type()

• BACKWARD INCOMPATIBLE Removed the check_argument_types() and check_return_type() functions (use @typechecked instead)

• BACKWARD INCOMPATIBLE Moved install_import_hook to be directly importable from the typeguard module

• BACKWARD INCOMPATIBLE Changed the checking of collections (list, set, dict, sequence, mapping) to only check the first item by default. To get the old behavior, set typeguard.config.collection_check_strategy to CollectionCheckStrategy.ALL_ITEMS

• BACKWARD INCOMPATIBLE Type checking failures now raise typeguard.TypeCheckError instead of TypeError

• Dropped Python 3.5 and 3.6 support

• Dropped the deprecated profiler hook (TypeChecker)

• Added a configuration system

• Added support for custom type checking functions

• Added support for PEP 604 union types (X | Y) on all Python versions

• Added support for generic built-in collection types (list[int] et al) on all Python versions

• Added support for checking arbitrary Mapping types

• Added support for the Self type

• Added support for typing.Never (and typing_extensions.Never)

• Added support for Never and NoReturn in argument annotations

• Added support for LiteralString

• Added support for TypeGuard

• Added support for the subclassable Any on Python 3.11 and typing_extensions

• Added the possibility to have the import hook instrument all packages

• Added the suppress_type_checks() context manager function for temporarily disabling type checks

• Much improved error messages showing where the type check failed

• Made it possible to apply @typechecked on top of @classmethod / @staticmethod (PR by jacobpbrugh)

• Changed check_type() to return the passed value, so it can be used (to an extent) in place of typing.cast(), but with run-time type checking

• Replaced custom implementation of is_typeddict() with the implementation from typing_extensions v4.1.0

• Emit InstrumentationWarning instead of raising RuntimeError from the pytest plugin if modules in the target package have already been imported

• Fixed TypeError when checking against TypedDict when the value has mixed types among the extra keys (PR by biolds)

• Fixed incompatibility with typing_extensions v4.1+ on Python 3.10 (PR by David C.)

• Fixed checking of Tuple[()] on Python 3.11 and tuple[()] on Python 3.9+

• Fixed integers 0 and 1 passing for Literal[False] and Literal[True], respectively

• Fixed type checking of annotated variable positional and keyword arguments (*args and **kwargs)

• Fixed checks against unittest.Mock and derivatives being done in the wrong place

2.13.3 (2021-12-10)

• Fixed TypeError when using typeguard within exec() (where __module__ is None) (PR by Andy Jones)

• Fixed TypedDict causing TypeError: TypedDict does not support instance and class checks on Python 3.8 with standard library (not typing_extensions) typed dicts

2.13.2 (2021-11-23)

• Fixed typing_extensions being imported unconditionally on Python < 3.9 (bug introduced in 2.13.1)

2.13.1 (2021-11-23)

• Fixed @typechecked replacing abstract properties with regular properties

• Fixed any generic type subclassing Dict being mistakenly checked as TypedDict on Python 3.10

2.13.0 (2021-10-11)

• Added support for returning NotImplemented from binary magic methods (__eq__() et al)

• Added support for checking union types (e.g. Type[Union[X, Y]])

• Fixed error message when a check against a Literal fails in a union on Python 3.10

• Fixed NewType not being checked on Python 3.10

• Fixed unwarranted warning when @typechecked is applied to a class that contains unannotated properties

• Fixed TypeError in the async generator wrapper due to changes in __aiter__() protocol

• Fixed broken TypeVar checks – variance is now (correctly) disregarded, and only bound types and constraints are checked against (but type variable resolution is not done)

2.12.1 (2021-06-04)

• Fixed AttributeError when __code__ is missing from the checked callable (PR by epenet)

2.12.0 (2021-04-01)

• Added @typeguard_ignore decorator to exclude specific functions and classes from runtime type checking (PR by Claudio Jolowicz)

2.11.1 (2021-02-16)

• Fixed compatibility with Python 3.10

2.11.0 (2021-02-13)

• Added support for type checking class properties (PR by Ethan Pronovost)

• Fixed static type checking of @typechecked decorators (PR by Kenny Stauffer)

• Fixed wrong error message when type check against a bytes declaration fails

• Allowed memoryview objects to pass as bytes (like MyPy does)

• Shortened tracebacks (PR by prescod)

2.10.0 (2020-10-17)

• Added support for Python 3.9 (PR by Csergő Bálint)

• Added support for nested Literal

• Added support for TypedDict inheritance (with some caveats; see the user guide on that for details)

• An appropriate TypeError is now raised when encountering an illegal Literal value

• Fixed checking NoReturn on Python < 3.8 when typing_extensions was not installed

• Fixed import hook matching unwanted modules (PR by Wouter Bolsterlee)

• Install the pytest plugin earlier in the test run to support more use cases (PR by Wouter Bolsterlee)

2.9.1 (2020-06-07)

• Fixed ImportError on Python < 3.8 when typing_extensions was not installed

2.9.0 (2020-06-06)

• Upped the minimum Python version from 3.5.2 to 3.5.3

• Added support for typing.NoReturn

• Added full support for typing_extensions (now equivalent to support of the typing module)

• Added the option of supplying check_type() with globals/locals for correct resolution of forward references

• Fixed erroneous TypeError when trying to check against non-runtime typing.Protocol (skips the check for now until a proper compatibility check has been implemented)

• Fixed forward references in TypedDict not being resolved

• Fixed checking against recursive types

2.8.0 (2020-06-02)

• Added support for the Mock and MagicMock types (PR by prescod)

• Added support for typing_extensions.Literal (PR by Ryan Rowe)

• Fixed unintended wrapping of untyped generators (PR by prescod)

• Fixed checking against bound type variables with check_type() without a call memo

• Fixed error message when checking against a Union containing a Literal

2.7.1 (2019-12-27)

• Fixed @typechecked returning None when called with always=True and Python runs in optimized mode

• Fixed performance regression introduced in v2.7.0 (the getattr_static() call was causing a 3x slowdown)

2.7.0 (2019-12-10)

• Added support for typing.Protocol subclasses

• Added support for typing.AbstractSet

• Fixed the handling of total=False in TypedDict

• Fixed no error reported on unknown keys with TypedDict

• Removed support of default values in TypedDict, as they are not supported in the spec

2.6.1 (2019-11-17)

• Fixed import errors when using the import hook and trying to import a module that has both a module docstring and __future__ imports in it

• Fixed AttributeError when using @typechecked on a metaclass

• Fixed @typechecked compatibility with built-in function wrappers

• Fixed type checking generator wrappers not being recognized as generators

• Fixed resolution of forward references in certain cases (inner classes, function-local classes)

• Fixed AttributeError when a class has contains a variable that is an instance of a class that has a __call__() method

• Fixed class methods and static methods being wrapped incorrectly when @typechecked is applied to the class

• Fixed AttributeError when @typechecked is applied to a function that has been decorated with a decorator that does not properly wrap the original (PR by Joel Beach)

• Fixed collections with mixed value (or key) types raising TypeError on Python 3.7+ when matched against unparametrized annotations from the typing module

• Fixed inadvertent TypeError when checking against a type variable that has constraints or a bound type expressed as a forward reference

2.6.0 (2019-11-06)

• Added a PEP 302 import hook for annotating functions and classes with @typechecked

• Added a pytest plugin that activates the import hook

• Added support for typing.TypedDict

• Deprecated TypeChecker (will be removed in v3.0)

2.5.1 (2019-09-26)

• Fixed incompatibility between annotated Iterable, Iterator, AsyncIterable or AsyncIterator return types and generator/async generator functions

• Fixed TypeError being wrapped inside another TypeError (PR by russok)

2.5.0 (2019-08-26)

• Added yield type checking via TypeChecker for regular generators

• Added yield, send and return type checking via @typechecked for regular and async generators

• Silenced TypeChecker warnings about async generators

• Fixed bogus TypeError on Type[Any]

• Fixed bogus TypeChecker warnings when an exception is raised from a type checked function

• Accept a bytearray where bytes are expected, as per python/typing#552

• Added policies for dealing with unmatched forward references

• Added support for using @typechecked as a class decorator

• Added check_return_type() to accompany check_argument_types()

• Added Sphinx documentation

2.4.1 (2019-07-15)

• Fixed broken packaging configuration

2.4.0 (2019-07-14)

• Added PEP 561 support

• Added support for empty tuples (Tuple[()])

• Added support for typing.Literal

• Make getting the caller frame faster (PR by Nick Sweeting)

2.3.1 (2019-04-12)

• Fixed thread safety issue with the type hints cache (PR by Kelsey Francis)

2.3.0 (2019-03-27)

• Added support for typing.IO and derivatives

• Fixed return type checking for coroutine functions

• Dropped support for Python 3.4

2.2.2 (2018-08-13)

• Fixed false positive when checking a callable against the plain typing.Callable on Python 3.7

2.2.1 (2018-08-12)

• Argument type annotations are no longer unioned with the types of their default values, except in the case of None as the default value (although PEP 484 still recommends against this)

• Fixed some generic types (typing.Collection among others) producing false negatives on Python 3.7

• Shortened unnecessarily long tracebacks by raising a new TypeError based on the old one

• Allowed type checking against arbitrary types by removing the requirement to supply a call memo to check_type()

• Fixed AttributeError when running with the pydev debugger extension installed

• Fixed getting type names on typing.* on Python 3.7 (fix by Dale Jung)

2.2.0 (2018-07-08)

• Fixed compatibility with Python 3.7

• Removed support for Python 3.3

• Added support for typing.NewType (contributed by reinhrst)

2.1.4 (2018-01-07)

• Removed support for backports.typing, as it has been removed from PyPI

• Fixed checking of the numeric tower (complex -> float -> int) according to PEP 484

2.1.3 (2017-03-13)

• Fixed type checks against generic classes

2.1.2 (2017-03-12)

• Fixed leak of function objects (should’ve used a WeakValueDictionary instead of WeakKeyDictionary)

• Fixed obscure failure of TypeChecker when it’s unable to find the function object

• Fixed parametrized Type not working with type variables

• Fixed type checks against variable positional and keyword arguments

2.1.1 (2016-12-20)

• Fixed formatting of README.rst so it renders properly on PyPI

2.1.0 (2016-12-17)

• Added support for typings.Type (available in Python 3.5.2+)

• Added a third, sys.setprofile() based type checking approach (typeguard.TypeChecker)

• Changed certain type error messages to display “function” instead of the function’s qualified name

2.0.2 (2016-12-17)

• More Python 3.6 compatibility fixes (along with a broader test suite)

2.0.1 (2016-12-10)

• Fixed additional Python 3.6 compatibility issues

2.0.0 (2016-12-10)

• BACKWARD INCOMPATIBLE Dropped Python 3.2 support

• Fixed incompatibility with Python 3.6

• Use inspect.signature() in place of inspect.getfullargspec

• Added support for typing.NamedTuple

1.2.3 (2016-09-13)

• Fixed @typechecked skipping the check of return value type when the type annotation was None

1.2.2 (2016-08-23)

• Fixed checking of homogenous Tuple declarations (Tuple[bool, ...])

1.2.1 (2016-06-29)

• Use backports.typing when possible to get new features on older Pythons

• Fixed incompatibility with Python 3.5.2

1.2.0 (2016-05-21)

• Fixed argument counting when a class is checked against a Callable specification

• Fixed argument counting when a functools.partial object is checked against a Callable specification

• Added checks against mandatory keyword-only arguments when checking against a Callable specification

1.1.3 (2016-05-09)

• Gracefully exit if check_type_arguments can’t find a reference to the current function

1.1.2 (2016-05-08)

• Fixed TypeError when checking a builtin function against a parametrized Callable

1.1.1 (2016-01-03)

• Fixed improper argument counting with bound methods when typechecking callables

1.1.0 (2016-01-02)

• Eliminated the need to pass a reference to the currently executing function to check_argument_types()

1.0.2 (2016-01-02)

• Fixed types of default argument values not being considered as valid for the argument

1.0.1 (2016-01-01)

• Fixed type hints retrieval being done for the wrong callable in cases where the callable was wrapped with one or more decorators

1.0.0 (2015-12-28)

• Initial release