function_class.py File Reference

Library for making python classes from a set of functions. More...

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Data Structures
class	python.function_class.ClassFromFunctions

Functions
	python.function_class.method_function_returns_instance (method_function, cls)
	python.function_class.method_function_returns_instance_list (method_function, cls)
	python.function_class.methods_return_instance_lists (cls, function_dict)
	python.function_class.default_arguments_decorator (function, *args, **kargs)
	Decorates a function to give it default, positional and keyword arguments.
	python.function_class.return_instance_if_value_has_it (value)
	python.function_class.process_list_convert_to_instance (value_list)
	python.function_class.process_dict_convert_to_instance (value_dict)
	python.function_class.extract_attributes_with_prefix (obj, prefix)
	python.function_class.methods_return_instance (cls, function_dict)

Variables
str	python.function_class.INSTANCE_ARGUMENT = "instance"

Detailed Description

Library for making python classes from a set of functions.

Author

Mark Jenkins, ParIT Worker Co-operative mark@.nosp@m.pari.nosp@m.t.ca

Jeff Green, ParIT Worker Co-operative jeff@.nosp@m.pari.nosp@m.t.ca

Definition in file function_class.py.

Function Documentation

default_arguments_decorator()

python.function_class.default_arguments_decorator	(		function,
		*	args,
		**	kargs
	)

Decorates a function to give it default, positional and keyword arguments.

mimics python behavior when setting defaults in function/method arguments. arguments can be set for positional or keyword arguments.

kargs_pos contains positions of the keyword arguments.

Exceptions

A	TypeError will be raised if an argument is set as a positional and keyword argument at the same time.

Note

It might be possible to get keyword argument positional information using introspection to avoid having to specify them manually

a keyword argument default will be overwritten by a positional argument at the actual function call

this function modifies the docstring of the wrapped function to reflect the defaults.

You can't use this decorator with @, because this function has more than one argument.

arguments:

Parameters

*args	optional positional defaults
kargs_pos	dict with keyword arguments as key and their position in the argument list as value
**kargs	optional keyword defaults

Returns

new_function wrapping original function

Definition at line 262 of file function_class.py.

def default_arguments_decorator(function, *args, **kargs):
    """! Decorates a function to give it default, positional and keyword arguments
 
    mimics python behavior when setting defaults in function/method arguments.
    arguments can be set for positional or keyword arguments.
 
    kargs_pos contains positions of the keyword arguments.
    @exception A TypeError will be raised if an argument is set as a positional and keyword argument
    at the same time.
    @note It might be possible to get keyword argument positional information using
    introspection to avoid having to specify them manually
 
    a keyword argument default will be overwritten by a positional argument at the
    actual function call
 
    this function modifies the docstring of the wrapped function to reflect
    the defaults.
 
    You can't use this decorator with @, because this function has more
    than one argument.
 
    arguments:
    @param *args: optional positional defaults
    @param kargs_pos: dict with keyword arguments as key and their position in the argument list as value
    @param **kargs: optional keyword defaults
 
    @return new_function wrapping original function
    """
 
    def new_function(*function_args, **function_kargs):
        kargs_pos = {}
        if "kargs_pos" in kargs:
            kargs_pos = kargs.pop("kargs_pos")
        new_argset = list(function_args)
        new_argset.extend(args[len(function_args) :])
        new_kargset = {**kargs, **function_kargs}
        for karg_pos in kargs_pos:
            if karg_pos in new_kargset:
                pos_karg = kargs_pos[karg_pos]
                if pos_karg < len(new_argset):
                    new_kargset.pop(karg_pos)
 
        return function(*new_argset, **new_kargset)
 
    kargs_pos = {} if "kargs_pos" not in kargs else kargs["kargs_pos"]
    for karg_pos in kargs_pos:
        if karg_pos in kargs:
            pos_karg = kargs_pos[karg_pos]
            if pos_karg < len(args):
                raise TypeError(
                    "default_arguments_decorator() got multiple values for argument '%s'"
                    % karg_pos
                )
 
    if new_function.__doc__ is None:
        new_function.__doc__ = ""
    if len(args):
        firstarg = True
        new_function.__doc__ += "positional argument defaults:\n"
        for arg in args:
            if not firstarg:
                new_function.__doc__ += ", "
            else:
                new_function.__doc__ += "  "
                firstarg = False
            new_function.__doc__ += str(arg)
        new_function.__doc__ += "\n"
    if len(kargs):
        new_function.__doc__ += "keyword argument defaults:\n"
        for karg in kargs:
            if karg != "kargs_pos":
                new_function.__doc__ += (
                    "  " + str(karg) + " = " + str(kargs[karg]) + "\n"
                )
        if kargs_pos:
            new_function.__doc__ += "keyword argument positions:\n"
            for karg in kargs_pos:
                new_function.__doc__ += (
                    "  " + str(karg) + " is at pos " + str(kargs_pos[karg]) + "\n"
                )
    if len(args) or len(kargs):
        new_function.__doc__ += (
            "(defaults have been set by default_arguments_decorator method)"
        )
    return new_function
 
 

extract_attributes_with_prefix()

python.function_class.extract_attributes_with_prefix	(		obj,
			prefix
	)

Generator that iterates through the attributes of an object and
for any attribute that matches a prefix, this yields
the attribute name, the attribute value, and the text that appears
after the prefix in the name

Definition at line 380 of file function_class.py.

def extract_attributes_with_prefix(obj, prefix):
    """Generator that iterates through the attributes of an object and
    for any attribute that matches a prefix, this yields
    the attribute name, the attribute value, and the text that appears
    after the prefix in the name
    """
    for attr_name, attr_value in iter(obj.__dict__.items()):
        if attr_name.startswith(prefix):
            after_prefix = attr_name[ len(prefix): ]
            yield attr_name, attr_value, after_prefix
 

method_function_returns_instance()

python.function_class.method_function_returns_instance	(		method_function,
			cls
	)

A function decorator that is used to decorate method functions that
return instance data, to return instances instead.

You can't use this decorator with @, because this function has a second
argument.

Definition at line 233 of file function_class.py.

def method_function_returns_instance(method_function, cls):
    """A function decorator that is used to decorate method functions that
    return instance data, to return instances instead.
 
    You can't use this decorator with @, because this function has a second
    argument.
    """
    assert( 'instance' == INSTANCE_ARGUMENT )
    def new_function(*args, **kargs):
        kargs_cls = { INSTANCE_ARGUMENT : method_function(*args, **kargs) }
        if kargs_cls['instance'] == None:
            return None
        else:
            return cls( **kargs_cls )
 
    return new_function
 

method_function_returns_instance_list()

python.function_class.method_function_returns_instance_list	(		method_function,
			cls
	)

Definition at line 250 of file function_class.py.

def method_function_returns_instance_list(method_function, cls):
    def new_function(*args, **kargs):
        return [ cls( **{INSTANCE_ARGUMENT: item} )
                 for item in method_function(*args, **kargs) ]
    return new_function
 

methods_return_instance()

python.function_class.methods_return_instance	(		cls,
			function_dict
	)

Iterates through a dictionary of function name strings and instance names
and sets the function to return the associated instance

Definition at line 391 of file function_class.py.

def methods_return_instance(cls, function_dict):
    """Iterates through a dictionary of function name strings and instance names
    and sets the function to return the associated instance
    """
    for func_name, instance_name in iter(function_dict.items()):
        setattr(cls, func_name,
            method_function_returns_instance( getattr(cls, func_name), instance_name))
 

methods_return_instance_lists()

python.function_class.methods_return_instance_lists	(		cls,
			function_dict
	)

Definition at line 256 of file function_class.py.

def methods_return_instance_lists(cls, function_dict):
    for func_name, instance_name in iter(function_dict.items()):
        setattr(cls, func_name,
                method_function_returns_instance_list(
                getattr(cls, func_name), instance_name))
 

process_dict_convert_to_instance()

python.function_class.process_dict_convert_to_instance

(

value_dict

)

Return a dict built from value_dict, where if a value is in an instance
of ClassFromFunctions, we put value.instance in the dict instead.

Things that are not instances of ClassFromFunctions are returned to
the new dict unchanged.

Definition at line 368 of file function_class.py.

def process_dict_convert_to_instance(value_dict):
    """Return a dict built from value_dict, where if a value is in an instance
    of ClassFromFunctions, we put value.instance in the dict instead.
 
    Things that are not instances of ClassFromFunctions are returned to
    the new dict unchanged.
    """
    return {
        key: return_instance_if_value_has_it(value) for key, value in value_dict.items()
    }
 
 

process_list_convert_to_instance()

python.function_class.process_list_convert_to_instance

(

value_list

)

Return a list built from value_list, where if a value is in an instance
of ClassFromFunctions, we put value.instance in the list instead.

Things that are not instances of ClassFromFunctions are returned to
the new list unchanged.

Definition at line 358 of file function_class.py.

def process_list_convert_to_instance( value_list ):
    """Return a list built from value_list, where if a value is in an instance
    of ClassFromFunctions, we put value.instance in the list instead.
 
    Things that are not instances of ClassFromFunctions are returned to
    the new list unchanged.
    """
    return [ return_instance_if_value_has_it(value)
             for value in value_list ]
 

return_instance_if_value_has_it()

python.function_class.return_instance_if_value_has_it

(

value

)

Return value.instance if value is an instance of ClassFromFunctions,
else return value

Definition at line 349 of file function_class.py.

def return_instance_if_value_has_it(value):
    """Return value.instance if value is an instance of ClassFromFunctions,
    else return value
    """
    if isinstance(value, ClassFromFunctions):
        return value.instance
    else:
        return value
 

Variable Documentation

INSTANCE_ARGUMENT

str python.function_class.INSTANCE_ARGUMENT = "instance"

Definition at line 29 of file function_class.py.