Whether a function parameter in Python is a value or a reference

A straightforward example:

　

1  fromcTYPESImport*2 ImportOs.path3 ImportSYS4 5 defTest (c):6     Print "Test before"7     PrintID (c)8c+=29     Print "Test after +"Ten     PrintID (c) One     returnC A  - defPrintIt (t): -      forIinchRange (len (t)): the         PrintT[i] -  - if __name__=="__main__": -a=2 +     Print "main before invoke test" -     PrintID (a) +n=Test (a) A     Print "main Afterf Invoke test" at     Printa -     PrintID (a)

The results are as follows:

>>>+main afterf invoke test39601564

Conclusion:

Python does not allow programmers to choose whether to use a value or to pass a reference. Python parameter passing is definitely a way to "pass an object reference". This approach is equivalent to a synthesis of the value of the pass and the reference. If a function receives a reference to a mutable object (such as a dictionary or a list), it can modify the original value of the object-the equivalent of passing the object through a "pass reference". If a function receives a reference to an immutable object (such as a number, character, or tuple), it cannot directly modify the original object-the equivalent of passing the object through a "pass value".

Whether a function parameter in Python is a value or a reference