ArgsLen Usage

ArgsLen decorartor that sets the number of args that can be added to a function.

Includes features:

ftype

opt_logger

opt_return

Single Length

Decorator can be applied with a single set Length. In the following example if anything other than 3 args are passed into foo a ValueError will be raised

from kwhelp.decorator import ArgsLen

@ArgsLen(3)
def foo(*args):
    return len(args)

Passing in three arg values works as expected.

>>> result = foo("a", "b", "c")
>>> print(result)
3

Passing in two args when three are expected raises a ValueError

>>> result = foo("a", "b")
ValueError: Invalid number of args pass into 'foo'.
Expected Length: '3'. Got '4' args.
ArgsLen decorator error.

Multiple Lengths

It is possible to allow more then one length to function by passing in multilple int values to decorator.

from kwhelp.decorator import ArgsLen

@ArgsLen(3, 5)
def foo(*args):
    return len(args)

Passing in 3 args.

>>> result = foo("a", "b", "c")
>>> print(result)
3

Passing in 5 args.

>>> result = foo("a", "b", "c", "d", "e")
>>> print(result)
5

Passing in 4 args result in a ValueError.

>>> result = foo("a", "b", "c", "d")
ValueError: Invalid number of args pass into 'foo'.
Expected Lengths: '3' or '5'. Got '4' args.
ArgsLen decorator error.

Ranges

It is possible to allow more then one length to function by passing in pairs of int values in the form of iterable values such as list or tuple values to decorator.

The following example allows 3, 4, 5, 7, 8, 9 args. Note that 1, 2, 6 or greater than 9 args will result in a ValueError.

from kwhelp.decorator import ArgsLen

@ArgsLen((3, 5), (7, 9))
def foo(*args):
    return len(args)

Passing in 3 args.

>>> result = foo("a", "b", "c")
>>> print(result)
3

Passing in 8 args.

from kwhelp.decorator import ArgsLen

>>> result = foo("a", "b", "c", "d", "e", "f", "g", "h")
>>> print(result)
8

Passing in 6 args.

>>> result = foo("a", "b", "c", "d", "e", "f")
ValueError: Invalid number of args pass into 'foo'.
Expected Ranges: (3, 5) or (7, 9). Got '6' args.
ArgsLen decorator error.

Ranges & Lengths

Ranges and lengths can be combined when needed.

The following example allows 3, 4, 5, 7, 8, 9 args. Note that 1, 2, 6 or greater than 9 args will result in a ValueError.

from kwhelp.decorator import ArgsLen

@ArgsLen(3, 4, 5, (7, 9))
def foo(*args):
    return len(args)

Passing in 3 args.

>>> result = foo("a", "b", "c")
>>> print(result)
3

Passing in 8 args.

>>> result = foo("a", "b", "c", "d", "e", "f", "g", "h")
>>> print(result)
8

Passing in 6 args.

>>> result = foo("a", "b", "c", "d", "e", "f")
ValueError: Invalid number of args pass into 'foo'.
Expected Lengths: '3', '4', or '5'. Expected Range: (7, 9). Got '6' args.
ArgsLen decorator error.

Class

Decorator can be used on class methods by setting ftype arg. to a value of DecFuncEnum.

Normal class

from kwhelp.decorator import ArgsLen

class Foo:
    @ArgsLen(0, (2, 4), ftype=DecFuncEnum.METHOD)
    def __init__(self, *args): pass

    @ArgsLen(3, 5, ftype=DecFuncEnum.METHOD)
    def bar(self, *args): pass

Static method

from kwhelp.decorator import ArgsLen

class Foo:
    @staticmethod
    @ArgsLen(3, 5, ftype=DecFuncEnum.METHOD_STATIC)
    def bar(self, *args): pass

Class method

from kwhelp.decorator import ArgsLen

class Foo:
    @staticmethod
    @ArgsLen(3, 5, ftype=DecFuncEnum.METHOD_CLASS)
    def bar(self, *args): pass