blob: 1bff85812856cf9b4024387c7ab4b3cdb329353a [file] [log] [blame]
#!/usr/bin/env python
r"""
This module provides argument manipulation functions like pop_arg.
"""
import gen_print as gp
import collections
def pop_arg(default, *args, **kwargs):
r"""
Pop a named argument from the args/kwargs and return a tuple consisting of
the argument value, the modified args and the modified kwargs.
The name of the argument is determined automatically by this function by
examining the source code which calls it (see examples below). If no
suitable argument can be found, the default value passed to this function
will be returned as the argument value. This function is useful for
wrapper functions that wish to process arguments in some way before
calling subordinate function.
Examples:
Given this code:
def func1(*args, **kwargs):
last_name, args, kwargs = pop_arg('Doe', *args, **kwargs)
some_function(last_name.capitalize(), *args, **kwargs)
Consider this call to func1:
func1('Johnson', ssn='111-11-1111')
The pop_arg in func1 would return the following:
'Johnson', [], {'ssn': "111-11-1111"}
Notice that the 'args' value returned is an empty list. Since last_name
was assumed to be the first positional argument, it was popped from args.
Now consider this call to func1:
func1(last_name='Johnson', ssn='111-11-1111')
The pop_arg in func1 would return the same last_name value as in the
previous example. The only difference being that the last_name value was
popped from kwargs rather than from args.
Description of argument(s):
default The value to return if the named argument
is not present in args/kwargs.
args The positional arguments passed to the
calling function.
kwargs The keyword arguments passed to the
calling function.
"""
# Retrieve the argument name by examining the source code.
arg_name = gp.get_arg_name(None, arg_num=-3, stack_frame_ix=2)
if arg_name in kwargs:
arg_value = kwargs.pop(arg_name)
else:
# Convert args from a tuple to a list.
args = list(args)
if args:
arg_value = args.pop(0)
else:
arg_value = default
return arg_value, args, kwargs
def source_to_object(value):
r"""
Evaluate string value as python source code and return the resulting
object.
If value is NOT a string or can not be interpreted as a python source
object definition, simply return value.
The idea is to convert python object definition source code (e.g. for
lists, dictionaries, tuples, etc.) into an object.
Example:
Note that this first example is a special case in that it is a short-cut
for specifying a collections.OrderedDict.
result = source_to_object("[('one', 1), ('two', 2), ('three', 3)]")
The result is a collections.OrderedDict object:
result:
[one]: 1
[two]: 2
[three]: 3
This is a short-cut for the long form shown here:
result = source_to_object("collections.OrderedDict([
('one', 1),
('two', 2),
('three', 3)])")
Also note that support for this special-case short-cut precludes the
possibility of interpreting such a string as a list of tuples.
Example:
In this example, the result will be a list:
result = source_to_object("[1, 2, 3]")
result:
result[0]: 1
result[1]: 2
result[2]: 3
Example:
In this example, the value passed to this function is not a string, so it
is simply returned.
result = source_to_object(1)
More examples:
result = source_to_object("dict(one=1, two=2, three=3)")
result = source_to_object("{'one':1, 'two':2, 'three':3}")
result = source_to_object(True)
etc.
Description of argument(s):
value If value is a string, it will be evaluated
as a python statement. If the statement
is valid, the resulting object will be
returned. In all other cases, the value
will simply be returned.
"""
if type(value) not in gp.get_string_types():
return value
# Strip white space prior to attempting to interpret the string as python
# code.
value = value.strip()
# Try special case of collections.OrderedDict:
if value.startswith("["):
try:
return eval("collections.OrderedDict(" + value + ")")
except (TypeError, NameError, ValueError):
pass
try:
return eval(value)
except (NameError, SyntaxError):
pass
return value
def args_to_objects(args):
r"""
Run source_to_object() on each element in args and return the result.
Description of argument(s):
args A type of dictionary, list, set, tuple or
simple object whose elements are to be
converted via a call to source_to_object().
"""
type_of_dict = gp.is_dict(args)
if type_of_dict:
if type_of_dict == gp.dict_type():
return {k: source_to_object(v) for (k, v) in args.items()}
elif type_of_dict == gp.ordered_dict_type():
return collections.OrderedDict((k, v) for (k, v) in args.items())
elif type_of_dict == gp.dot_dict_type():
return DotDict((k, v) for (k, v) in args.items())
elif type_of_dict == gp.normalized_dict_type():
return NormalizedDict((k, v) for (k, v) in args.items())
# Assume args is list, tuple or set.
if type(args) in (list, set):
return [source_to_object(arg) for arg in args]
elif type(args) is tuple:
return tuple([source_to_object(arg) for arg in args])
return source_to_object(args)