What are the five types of parameters in python

This article mainly introduces what are the five types of parameters in python. It is very detailed and has a certain reference value. Friends who are interested must read it!

Examples of the use of five types of parameters of function

Python five types of parameters: position parameters, keyword parameters, default parameters, variable position and keyword parameters

Def f (print: {a}, b: {b}, c: {c}, d: {d}') 12

The default parameter c cannot be after the variable keyword parameter d.

Call f:

F: {'width': 10,' height': 20}: {'Magne 10,' Widthpieces 10, etc.) a 1, (2, 5), cpart 10, d: {'

The variable position parameter b argument is parsed into tuples (2J5), while c gets the default value of 10; d is parsed as a dictionary.

Call f again:

F (aplomb: ()): (), ()

An is the keyword parameter when an is passed into aqum1, but no value is passed for b _ # d, and c is passed into 12 instead of the default value.

Note that the parameter a can be either f (1) or f (axi1), which is more readable than the first one. It is recommended to use f (aqui1). If you want to force the use of f (axi1), you need to add an asterisk before it:

Def f (*, aformaitb): print (favoa: {a}, b: {b}')

If f (1) is called at this point, an error will be reported: TypeError: F () takes 0 positional arguments but 1 was given

Only f (axi1) can OK.

It shows that the previous * works, and it can only pass in keyword parameters, so how do you check the type of this parameter? With the help of python's inspect module:

In [22]: for name,val in signature (f) .parameters.items ():...: print (name,val.kind)...: a KEYWORD_ONLYb VAR_KEYWORD

You can see that the parameter an is of type KEYWORD_ONLY, that is, just a keyword parameter.

However, if f is defined as:

Def f (a quotation b): print (favoa: {a}, b: {b}')

View parameter types:

In [24]: for name,val in signature (f) .parameters.items ():...: print (name,val.kind)...: a POSITIONAL_OR_KEYWORDb VAR_POSITIONAL

You can see that the parameter a can be either a position parameter or a keyword parameter.

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