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classmethods

This example illustrates how to define "class methods" as found on class- based object-oriented programming languages such as Java or Objective-C. Logtalk classes are objects. Therefore, class methods are simply instance methods defined in the class of the class, i.e. in its meta-class.

This example defines the following objects:

[99, 105, 114, 99, 108, 101]

class representing common features of geometric circles such as radius and position

[109, 101, 116, 97, 99, 105, 114, 99, 108, 101]

meta-class of class circle defining "class methods" for creating instances and calculating areas

[99, 52, 50]

static instance of class circle

Print Logtalk, Prolog backend, and kernel versions (if running as a notebook):

%versions

Start by loading the example:

logtalk_load(classmethods(loader)).

Use the class method area/2 to calculate the are of a circle given its radius:

circle::area(1.0, Area).

Ask our static instance, c42, its area:

c42::area(Area).

Create a dynamic instance of class circle using the class method new/4:

circle::new(1.2, 7.9, 2.0, Circle).

Ask the circle o1 its area:

o1::area(Area).