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Suppose I have a python function that takes two arguments, but I want the second arg to be optional, with the default being whatever was passed as the first argument. So, I want to do something like this:
def myfunc(arg1, arg2=arg1): print (arg1, arg2) Except that doesn't work. The only workaround I can think of is this:
def myfunc(arg1, arg2=None): if arg2 is None: arg2 = arg1 print (arg1, arg2) Is there a better way to do this?
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In addition to passing arguments to functions via a function call, you can also set default argument values in Python functions. These default values are assigned to function arguments if you do not explicitly pass a parameter value to the given argument. Parameters are the values actually passed to function arguments.
Python allows function arguments to have default values. If the function is called without the argument, the argument gets its default value.
In C++ programming, we can provide default values for function parameters. If a function with default arguments is called without passing arguments, then the default parameters are used. However, if arguments are passed while calling the function, the default arguments are ignored.
5 Types of Arguments in Python Function Definition:keyword arguments. positional arguments. arbitrary positional arguments. arbitrary keyword arguments.
As @Ignacio says, you can't do this. In your latter example, you might have a situation where None is a valid value for arg2. If this is the case, you can use a sentinel value:
sentinel = object() def myfunc(arg1, arg2=sentinel): if arg2 is sentinel: arg2 = arg1 print (arg1, arg2) myfunc("foo") # Prints 'foo foo' myfunc("foo", None) # Prints 'foo None' If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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