argvalidate Module

Below you can find the documentation of the public API of argvalidate.

Even though more constants, decorators, exceptions and functions may be specified in the argvalidate module, only those described here form the API and are intended for public use.

Note

Do not rely on any internals of argvalidate, as these may change at any time, without further notice.

The API described here forms the public interface to argvalidate and as such will have functionality pending for removal deprecated first.

Decorators

argvalidate.accepts(*type_args, **type_kwargs)

Decorator used for checking arguments passed to a function or method.

Parameters:

• start – method/function-detection override. The number of arguments defined with start are ignored in all checks.
• type_args – type definitions of non-keyword arguments.
• type_kwargs – type definitions of keyword arguments.

Raises DecoratorNonKeyLengthException:  

Raised if the number of non-keyword arguments specified in the decorator does not match the number of non-keyword arguments the function accepts.

Raises DecoratorKeyLengthException:  

Raised if the number of keyword arguments specified in the decorator does not match the number of non-keyword arguments the function accepts.

Raises DecoratorKeyUnspecifiedException:  

Raised if a keyword argument’s type has not been specified in the decorator.

Raises ArgumentTypeException:  

Raised if an argument type passed to the function does not match the type specified in the decorator.

Example:

class MyClass:
    @accepts(int, str)
    def my_method(self, x_is_int, y_is_str):
        [...]

@accepts(int, str)
def my_function(x_is_int, y_is_str):
    [....]

argvalidate.returns(expected_type)

Decorator used for checking the return value of a function or method.

Parameters:

• expected_type – expected type or return value

Raises ReturnValueTypeException:  

Raised if the return value’s type does not match the definition in the decorator’s expected_type parameter.

Example:

@return_value(int)
def my_func():
    return 5

Note

Stacking of decorator of the same type (ie. accepts() and accepts(), returns() and returns()) is not possible and will cause a DecoratorStackingException to be raised.

Stacking of different types of decorators (ie. returns() and accepts()) is possible though and will neither raise an exception nor break anything.

argvalidate.func_args(*type_args, **type_kwargs)

Wrapper for backwards-compatibility.

Deprecated:This decorator has been replaced with accepts().

argvalidate.method_args(*type_args, **type_kwargs)

Wrapper for backwards-compatibility.

Deprecated:This decorator has been replaced with accepts().

argvalidate.return_value(expected_type)

Wrapper for backwards-compatibility.

Deprecated:This decorator has been replaced with returns().

Helpers

argvalidate.one_of(*args)

Simple helper function to create a tuple from every argument passed to it.

Parameters:

• args – type definitions

A tuple can be used instead of calling this function, however, the tuple returned by this function contains a customized __repr__ method, which makes Exceptions easier to read.

Example:

@func_check_args(one_of(int, str, float))
def my_func(x):
    pass

argvalidate.raises_exceptions()

Returns True if argvalidate raises exceptions, False if argvalidate creates warnings instead.

This behaviour can be controlled via the environment variable ARGVALIDATE_WARN.

argvalidate.warns_kwarg_as_arg()

Returns True if argvalidate generates warnings for keyword arguments passed as arguments.

This behaviour can be controlled via the environment variable ARGVALIDATE_WARN_KWARG_AS_ARG.

Exceptions

exception argvalidate.ArgvalidateException

Base argvalidate exception.

Used as base for all exceptions.

exception argvalidate.ArgumentTypeException

Exception for invalid argument type.

This exception provides the following attributes:

• func_name

  Name of function that caused the exception to be raised (str, read-only).

• arg_name

  Name of the keyword argument passed to the function, but not specified in the decorator (str, read-only).

• expected_type

  Argument type that was expected (type, read-only).

• passed_type

  Argument type that was passed to the function (type, read-only).

exception argvalidate.ReturnValueTypeException

Exception for invalid return value type.

This exception provides the following attributes:

• func_name

  Name of function that caused the exception to be raised (string, read-only).

• expected_type

  Argument type that was expected (type, read-only).

• passed_type

  Type of value returned by the function (type, read-only).

exception argvalidate.DecoratorNonKeyLengthException

Exception for invalid decorator non-keyword argument count.

This exception provides the following attributes:

• func_name

  Name of function that caused the exception to be raised (str, read-only).

• expected_count

  Number of arguments that were expected (int, read-only).

• passed_count

  Number of arguments that were passed to the function (int, read-only).

exception argvalidate.DecoratorKeyUnspecifiedException

Exception for unspecified decorator keyword argument.

This exception provides the following attributes:

• func_name

  Name of function that caused the exception to be raised (str, read-only).

• arg_name

  Name of the keyword argument passed to the function, but not specified in the decorator (str, read-only).

exception argvalidate.DecoratorStackingException

Exception for stacking a decorator with itself.

This exception provides the following attributes:

• func_name

  Name of function that caused the exception to be raised (str, read-only).

• decorator_name

  Name of the decorator that was stacked with itself (str, read-only).