python之在多级字典中获取和设置值的最佳实践

Possible Duplicate:
Checking a Dictionary using a dot notation string

有一个像这样的多级字典:

some_infomations = { 
    "root":{ 
        "sub":{ 
            "more_deep":{ 
                "not_enough": "Some value", 
                "another": "bla..bla" 
            } 
        }, 
        "more":{ 
            "more_deep":{ 
                "not_enough": "Some value", 
                "another": "bla..bla" 
            } 
        } 
    } 
} 

我有一个像 root.sub.more_deep.another 这样的碎屑字符串，有没有像 eval("some_infomations[root.sub. more_deep.another] = some_value")?