Merge dict or dict like object,, include OrderedDict。

mergedict.py

# -*- coding: utf-8 -*-
u'''合并字典，可用于配置信息合并

合并的原则是后来的数据优先
'''

def mergeable(target, source):
    '''
    >>> from collections import OrderedDict

    >>> mergeable({}, {})
    True
    >>> mergeable(OrderedDict(), {})
    True
    >>> mergeable({}, OrderedDict())
    True
    >>> mergeable('target', {})
    False
    >>> mergeable([], {})
    False
    >>> mergeable({}, 'source')
    False
    >>> mergeable({}, [])
    False
    '''
    if isinstance(target, (basestring, tuple, list)):
        return False

    if isinstance(source, (basestring, tuple, list)):
        return False

    if isinstance(target, dict) and isinstance(source, dict):
        return True

    return all((
        hasattr(target, 'keys'),
        hasattr(target, '__getitem__'),
        hasattr(target, '__setitem__'),

        hasattr(source, 'keys'),
        hasattr(target, '__getitem__'),
        ))


def merge_dict(target, source):
    '''
    >>> from collections import OrderedDict
    >>> merge_dict(OrderedDict(), OrderedDict([('a', 1)]))
    OrderedDict([('a', 1)])
    >>> merge_dict(OrderedDict([('a', 1)]), OrderedDict([('a', 2)]))
    OrderedDict([('a', 2)])
    >>> merge_dict(OrderedDict([('a', 1)]), OrderedDict([('b', 2)]))
    OrderedDict([('a', 1), ('b', 2)])
    '''
    assert mergeable(target, source)

    targetKeys = target.keys()
    sourceKeys = source.keys()

    for key in sourceKeys:
        source_value = source[key]
        if key in targetKeys:
            target_value = target[key]
            if mergeable(target_value, source_value):
                merge_dict(target_value, source_value)
            else:
                target[key] = source_value
        else:
            target[key] = source_value

    return target


if __name__ == '__main__':
    import doctest
    doctest.testmod()