Configuration

Configuration is a thin wrapper around PyYAML which extends already readable and powerful YAML with inheritance, composition and (so called) “object-graph configuration” features.

Note

This is origionally based on configure <http://configure.readthedocs.org/en/latest/> but it did not work with py3 and had other design issues to my mind.

Basic Usage

Configuration uses YAML as a configuration format so you can refre to Yaml specification <http://yaml.org/spec/> for details

Config File

test_list:
  - item1
  - item2
test_str: this is a test string
test_bool1: true
test_bool2: false
test_bool3: yes
test_bool4: no
test_int: 10
test_float: 3.14159
test_dict:
    sub_item: true

Loading the Config

config = Configuration(cfg_file)
assert 'test_list' in config
assert config.test_list == ['item1', 'item2']
assert config['test_list'] == ['item1', 'item2']

Advanced Usage

Configuration allows you to register your own special yaml tags, it comes with two by default !!ref & !!object

Ref Examples

ref_value: !!ref:some.dot.separated.path.to.a.value
re_value_with_suffix: !!ref:some.dot.separated.path.to.a.value:.log
suffix_ref_value: !!ref:some.dot.separated.path.to.a.value:!!ref:ref_value

some:
  dot:
    separated:
      path:
        to:
          a:
            value: worked

config = Configuration(cfg_file)
assert config.ref_value == 'worked'
assert config.re_value_with_suffix == 'worked.log'
assert config.suffix_ref_value == 'workedworked'

Object Examples

#module object/attribute
python_object1: !!object:sys.stdout

# object must be importable
python_object2: !!object:test_object_tag.MyTest1
    value: test passed

#test instantiating a class
python_instance1: !!object/call:test_object_tag.MyTest2
    args:
        - positional value
    kwargs:
        value: kwarg value

#test instantiating a class
python_instance2: !!object/call:test_object_tag.MyTest2
    - positional value2
    - kwarg value2

#test instantiating a class
python_instance3: !!object/call:test_object_tag.MyTest3
    kwarg1: kwargs value 1
    kwarg2: kwargs value 2
    kwarg4: kwargs value 4
    kwarg3: kwargs value 3

#test lazy instantiating a class
python_lazy1: !!object/lazy:test_object_tag.function

config = Configuration(cfg_file)
assert config.python_object1 is sys.stdout
assert config.python_object2.value == 'test passed'
assert isinstance(config.python_instance1, MyTest2)
assert isinstance(config.python_instance3, MyTest3)

# Show lazy loading
global X
assert X == 10
X = 'Test Bassed'
assert config.python_lazy1 == 'Test Bassed'
# Lazy loaded objects are NOT called more then once
X = 10
assert config.python_lazy1 == 'Test Bassed'

# classes used for testing
X = 10

class MyTest1:
    pass

class MyTest2:
    positional_arg = 'Bad'
    kwarg_value = 'Bad'

    def __init__(self, positional_arg, value=None):
        self.positional_arg = positional_arg
        self.kwarg_value = value

class MyTest3:
    def __init__(self, kwarg1=None, kwarg2=None, kwarg3=None, kwarg4=None):
        self.kwarg1 = kwarg1
        self.kwarg2 = kwarg2
        self.kwarg3 = kwarg3
        self.kwarg4 = kwarg4

def function():
    global X
    return X