[ Python 常見問題 ] Passing a dictionary to a function in python as keyword parameters

Source From Here 
Question 
I'd like to call a function in python using a dictionary. Here is some code: 

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1. d = dict(param='test')  
2.   
3. def f(param):  
4.     print param  
5.   
6. f(d)  

This prints {'param': 'test'} but I'd like it to just print test. I'd like it to work similarly for more parameters: 

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1. d = dict(p1=1, p2=2)  
2. def f2(p1,p2):  
3.     print p1, p2  
4. f2(d)  

Is this possible? 

How-To 
A few extra details that might be helpful to know (questions I had after reading this and went and tested): 

1. The function can have parameters that are not included in the dictionary 
2. You can not override a parameter that is already in the dictionary 
3. The dictionary can not have parameters that aren't in the function.

Let's consider a function as example: 

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1. def mytest(a=4, b=2):  
2.     print a, b  

Number 1: The function can have parameters that are not included in the dictionary 

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1. In [2]: mydict = {'a': 100}  
2.   
3. In [3]: mytest(**mydict)  
4. a=100; b=2  

Number 2: You can not override a parameter that is already in the dictionary 

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1. In [4]: mydict = {'a': 100, 'b': 200}  
2.   
3. In [5]: mytest(a=3, **mydict)  
4. ---------------------------------------------------------------------------  
5. TypeError                                 Traceback (most recent call last)  
6. 5-2fa5de36a628> in   

----> 1 mytest(a=3, **mydict)  

  

TypeError: mytest() got multiple values for keyword argument 'a'  

Number 3: The dictionary can not have parameters that aren't in the function. 

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1. In [6]: mydict = {'a': 100, 'b': 200, 'c': 300}  
2.   
3. In [7]: mytest(**mydict)  
4. ---------------------------------------------------------------------------  
5. TypeError                                 Traceback (most recent call last)  
6. 7-ba7ed7e145e9> in   

----> 1 mytest(**mydict)  

  

TypeError: mytest() got an unexpected keyword argument 'c'