apply-defaults 0.1.0

Apply values to optional params

# apply_defaults

Applies a set of values to a function's optional parameters, if nothing was
passed to them.

In a typical function, the passed value takes precedence, and if no value is
passed it takes the default value specified in the parameter list is used.

This adds another layer between those two. So the precedence becomes:

1. Passed values, otherwise
2. The values specified by the decorator, otherwise
3. The default value.

The values can come from the bound object, or a configuration file.

`apply_self` applies attributes from the bound object ("self"):

```python
from apply_defaults import apply_self

class MyObject:
def __init__(self):
self.foo = "foo"

@apply_self
def method(self, foo=None):
return foo

>>> # If 'foo' is not passed, the param is assigned the value of self.foo.
>>> MyObject().method()
'foo'
>>> # Overriding @apply_self by specifying a value for 'foo'.
>>> MyObject().method(foo="bar")
'bar'
```

`apply_config` applies the options from a ConfigParser:

```python
from apply_defaults import apply_config
from configparser import ConfigParser

config = ConfigParser()

@apply_config(config)
def my_func(foo=None)
return foo

>>> # There is no configuration yet, so my_func returns the optional
>>> # parameter's default value.
>>> my_func()
None
>>> config.read_dict({"general": {"foo": "foo"}})
>>> # If 'foo' is not passed, the param is assigned the value of 'foo' in the
>>> # configuration.
>>> my_func()
'foo'
>>> # Override @apply_config by specifying a value for 'foo'.
>>> my_func(foo="bar")
'bar'
```