Ruby Define Constant In Class

Uses the instance method.

Ruby define constant in class.

So this is the way ruby s constant lookup algorithm works. Here s a code example. Although constants should not be changed you can modify the internal states of the objects they reference as seen in. Usr bin ruby class example var1 100 var2 200 def show puts value of first constant is var1 puts value of second constant is var2 end end create objects object example new object show here var1 and var2 are constants.

A class in ruby always starts with the keyword class followed by the name of the class. It never looks in subclass and so it can t find a definition for the constant. Note that constants do not exist until a value is actually assigned to them. All the data members in the class are between the class definition and the end keyword.

As you can see the class object stored in the user constant is different after reloading. Class orange def squeeze puts here s your juice end end orange orange new orange squeeze. The class customer can be displayed as class customer end you terminate a class by using the keyword end. This will produce the following result.

A method is a thing your class can do. In ruby 1 9 this has been addressed by adding an optional parameter. The name should always be in initial capitals. Module constants true constants of module and.

It is very important to understand that ruby does not have a way to truly reload classes and modules in memory and have that reflected everywhere they are already used. Classes become more useful when you start adding instance methods instance variables to them. Ruby performs a lookup for the constant that follows a class or module keyword because it needs to know if the class or module is going to be created or reopened. Same class method as in 1 8.

6 1 reloading and stale objects. Your confusion is due to the fact that the class method module constants hides the instance method module constants for module. If the constant is not defined at that point it is not considered to be a missing constant autoloading is not triggered. When we call sub class instance foo via constant ruby searches for foo constant in myclass and its superclasses.

So just define your constants outside methods typically we want to have constant definitions at the top of your class so they are clearly visible. Module constants all constants one argument. Making ruby classes more useful.