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When to pass a variable as a parameter?
You should pass instance variables as parameters to your own method if the method doesn’t operate specifically on that instance variable. In the example above, the view’s frame is just another rectangle as far as the invalidateRect () method is concerned. This makes sense if the method is a utility method.
How to pass default argument value of an instance member to?
You may find it is a little safer to make a special value for the purpose (an object instance is all you need, as long as you hide it so that the calling code does not use the same instance) instead of None. Either way, you should check for this value with is, not ==.
What do objects know about their instance variables?
Things an object knows are its instance variables (state). Things an object does are its methods (behavior). Methods can use instance variables so that objects of the same type can behave differently. A method can have parameters]
How are arguments and parameters used in Java?
Arguments are the things you pass into the methods. An argument (a value like 2, “Foo”, or a reference to a Dog) lands face-down into a… wait for it… parameter. And a parameter is nothing more than a local variable. A variable with a type and a name, that can be used inside the body of the method.
When to use member variables as method parameters?
Member variables are effectively a global state from the point of view, what’s more, a mutable global state if said member changes during the method’s execution. By replacing member variable references with method parameters, we can effectively make a function pure.
When is a reference-type variable passed to a method?
When a Reference- type variable is passed to a method it means that we are passing the reference to the same memory location of a variable as that of actual parameters. So when a change is made in a method, the change also gets reflects outside of it.
What does it mean to pass a value to a method?
Passing a value-type variable to a method by value means passing a copy of the variable to the method. Any changes to the parameter that take place inside the method have no effect on the original data stored in the argument variable.