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Ruby Programming
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Calling a Method

You call a method by specifying a receiver, the name of the method, and optionally some parameters and an associated block.

connection.downloadMP3("jitterbug") { |p| showProgress(p) }

In this example, the object connection is the receiver, downloadMP3 is the name of the method, "jitterbug" is the parameter, and the stuff between the braces is the associated block.

For class and module methods, the receiver will be the class or module name.

File.size("testfile")
Math.sin(Math::PI/4)

If you omit the receiver, it defaults to self, the current object.

self.id 537794160
id 537794160
self.type Object
type Object

This defaulting mechanism is how Ruby implements private methods. Private methods may not be called with a receiver, so they must be methods available in the current object.

The optional parameters follow the method name. If there is no ambiguity you can omit the parentheses around the argument list when calling a method.[Other Ruby documentation sometimes calls these method calls without parentheses ``commands.''] However, except in the simplest cases we don't recommend this---there are some subtle problems that can trip you up.[In particular, you must use parentheses on a method call that is itself a parameter to another method call (unless it is the last parameter).] Our rule is simple: if there's any doubt, use parentheses.

a = obj.hash    # Same as
a = obj.hash()  # this.

obj.someMethod "Arg1", arg2, arg3   # Same thing as obj.someMethod("Arg1", arg2, arg3)  # with parentheses.
Ruby Programming
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