Read value in Python dict and checks if keys exists.

dict_read_value.py

def dict_read_value(src, path, default=None):                                  
    value = src                                                                

    keys = path.split('.')                                                     
    for key in keys:                                                           
        if isinstance(value, dict) and key in value:                                                       
            value = value[key]                                             
        else:                                                                  
            return default                                                     

    return value                                                               

# test
d = {'x': {'y': {'z': 1}}}                                                     

assert dict_read_value(d, 'x.y.z') == 1                                        
assert dict_read_value(d, 'x.x', -1) == -1                                     
assert dict_read_value(d, 'a.b.c', 0) == 0 

Zmenil som type(value) == dict -> isinstance(value, dict).

Tu je vysvetlene preco je lepsie pouzit isinstance: http://stackoverflow.com/questions/1549801/differences-between-isinstance-and-type-in-python .