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I was wondering if anyone had any good ways of quickly explaining how to efficiently and pythonically create user defined objects with optional arguments. For instance, I want to create this object:
class Object: def __init__(self, some_other_object, i, *j, *k): self.some_other_object = some_other_object self.i = i # If j is specified, assume it is = i if(j==None): self.j = i else: self.j = j # If k is given, assume 0 if(k==None): self.k = 0 else: self.k = k Is there a better way to do this?
EDIT: I changed the code so that it is more broad and more easily understood.
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To make an argument optional, you have to assign some default value to that argument. Here, to make the age argument optional, you can add a default value to the argument age in the function definition to make it optional. In this case, let's initialize it with 0 or any other value which you want.
A Python optional argument is a type of argument with a default value. You can assign an optional argument using the assignment operator in a function definition or using the Python **kwargs statement.
Sometimes, the programs require optional arguments when supplied will use them else go back to default declarations. We will see in this example on how to use them. The parameters that start with dashes (--) are identified as optional, so they can be left out, and they may have default values.
Here, the __init__() function will take two argument values at the time of the object creation that will be used to initialize two class variables, and another method of the class will be called to print the values of the class variables.
You can set default parameters:
class OpticalTransition(object): def __init__(self, chemical, i, j=None, k=0): self.chemical = chemical self.i = i self.k = k self.j = j if j is not None else i If you don't explicitly call the class with j and k, your instance will use the defaults you defined in the init parameters. So when you create an instance of this object, you can use all four parameters as normal: OpticalTransition('sodium', 5, 100, 27)
Or you can omit the parameters with defaults with OpticalTransition('sodium', 5), which would be interpreted as OpticalTransition('sodium', 5, None, 0)
You can use some default values but not all of them as well, by referencing the name of the parameter: OpticalTransition('sodium', 5, k=27) uses j's default but not k's.
Python won't allow you to do j=i as a default parameter (i isn't an existing object that the class definition can see), so the self.j line handles this with an if statement that in effect does the same thing.
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