Classdef and objects

Description

Define classes and objects in Scilab scripts

Definition

Classdef are used to define a set of properties and/or methods that work together. Properties are like variables and methods like functions.

classdef <classname> < <superclass> & <superclass>
    properties (<modifiers>)
        var1 = []
    end

    methods (<modifiers>)
        function <classname>(args...) // constructor
            ...
        end

        function rets=func1(args...)
            ...
        end

        func2 = externalfunc
    end

    enumeration
        enum1(args...)
        enum2(args...)
        enum3(args...)
    end
end

Classes are defined by :

Name: it will be used to use class
Superclass: names of superclass from which it derives
Properties: variables used inside or outside class to store data
Methods: functions to do some operations
Enumeration: Specific instances of class

Properties and Methods can have some modifiers to change their visibility or behavior:

Private: elements can be used only inside methods of this class. (Public/Protected/Private are exclusive)
Protected: elements can be used inside methods of this class and its children (inheritance). (Public/Protected/Pritave are exclusive)
Public (default): elements can be used outside and inside of this class. (Public/Protected/Pritave are exclusive)

inheritance

Classes can derive from one or multiple classes. (with &) In this case, elements of the parent classes can be used in this class (depends of the modifiers)

classdef <classname> < <superclass> & <superclass>
end

Properties

Define properties of class. Visibility modifier can be private, protected or public. A default value can be added to initialize variable during instantiation (default [])

classdef <classname>
    properties (<modifier>)
        var1 = []
    end
end

Methods

Define methods of class. Visibility modifier can be private, protected or public. In methods this must be used to access to properties or methods of the object

classdef <classname>
    methods (<modifier>)
        function rets=func(args...)
            this.var1 = 12;
        end

        func2 = externalfunc
    end
end

Note: externalfunc can be a macro or a C/C++ gateway.

In C/C++ gateway, use symbol::Context::getInstance()->getCurrentObject() to get this

Emuneration

Define enumeration of class. They are specific instances of the class associated to a name.

classdef Color
    enumeration
        RED     (args...)
        GREEN   (args...)
        BLUE    (args...)
    end
end

//usage
Color.RED
Color.GREEN
Color.BLUE

Overloads

Overloads will be called for undefined operations or function calls. (overloading)

There is 2 forms:

External: defining an overload function %type1_operator_type2 for operators (standard overload way in Scilab)

Or %type_function for functions

Internal: using methods declaration in classdef

For functions, define a method with the same name (ex: disp in following example)

There is special functions called by internal mecanism like:

saveobj: call when saving an object to serialize data.
prototype: function data=saveobj(), end

You have to return a native scilab variable (struct, list, ...) except objects that contains all data you want to save.
loadobj: called when object is restore by load function.
prototype: function loadobj(data), end

data is the variable returned by saveobj.
delete: called when object is cleared
prototype: function delete(), end

For operators following the lookup table :

Operations	Methods to define	Operations	Methods to define	Operations	Methods to define	Operations	Methods to define
a `+` b	plus(a, b)	+a	uplus(a)	a - b	minus(a, b)	-a	uminus(a)
a * b	mtimes(a, b)	a / b	mrdivide(a, b)	a \ b	mldivide(a, b)	a ^ b	mpower(a, b)
a .* b	times(a, b)	a ./ b	rdivide(a, b)	a .\ b	ldivide(a, b)	a .^ b	power(a, b)
a .*. b	kron(a, b)	a ./. b	rkron(a, b)	a .\. b	lkron(a, b)
a *. b	controltimes(a, b)	a /. b	controlrdivide(a, b)	a \. b	controlldivide(a, b)

Comparisions	Methods to define	Comparisions	Methods to define
a == b	eq(a, b)	a <> b	ne(a, b)
a < b	lt(a, b)	a <= b	le(a, b)
a > b	gt(a, b)	a >= b	ge(a, b)
a & b	and(a, b)	a \| b	or(a, b)
a && b	shortand(a, b)	a \|\| b	shortor(a, b)

Operations	Methods to define	Operations	Methods to define	Operations	Methods to define
~a	not(a)	a'	ctranspose(a)	a.'	transpose(a)

Matrix manipulations	Methods to define	Matrix manipulations	Methods to define
[a b]	horzcat(a, b)	[a;b]	vertcat(a, b)
a(i1, i2, ...)	extract(i1, i2, ...)	a(i1, i2, ...) = b	insert(i1, i2, ..., b)

for the most part of overload, you can definie a specific one for a identitified type.

ex: insert_s (insertion of a double in the object).

generic one will be used if specific one does not exist.

Search order is: specific (insert_s), generic (insert), scilab standard (%type1_i_type2)

classdef Matrix
    properties
        value = []
    end
    methods
        function Matrix(v)
            this.value = v;
        end

        function r=plus(a, b) //generic overload for operation +
            if isa(a, "Matrix") & isa(b, "Matrix") then
                r = Matrix(a.value + b.value);
            else
                error(sprintf("Operation + not defined for %s and %s.\n", typeof(a), typeof(b)));
            end
        end

        function r=plus_s(a, b) //overload for Matrix + double or double + Matrix
            if isa(a, "Matrix") then
                r = Matrix(a.value + b);
            else
                r = Matrix(a + b.value);
            end
        end

        function r=plus_i(a, b) //overload for Matrix + int or int + Matrix
            if isa(a, "Matrix") then
                r = Matrix(a.value + double(b));
            else
                r = Matrix(double(a) + b.value);
            end
        end

        function disp()
            disp(this.value);
        end
    end
end

a = Matrix([1 2 3 4]);
b = Matrix([4 3 2 1]);
a + b
a + 10
10 + b
a + int8(10)
int8(10) + b

Examples

Usage of enumeration:

classdef Color
    properties
        R
        G
        B
    end

    methods
        function Color(varargin)
            s = size(varargin);

            select (s)
            case 1
                c = varargin(1);
                [_, _, _, colors] = regexp(c, "/([0-9A-Fa-f]{1,2})([0-9A-Fa-f]{1,2})([0-9A-Fa-f]{1,2})/");

                colors = hex2dec(part(colors + colors, 1:2));
                this.R = colors(1);
                this.G = colors(2);
                this.B = colors(3);
            case 3
                this.R = modulo(varargin(1), 256);
                this.G = modulo(varargin(2), 256);
                this.B = modulo(varargin(3), 256);
            end
        end

        function disp()
            printf("Color: #%02x%02x%02x\n", this.R, this.G, this.B);
        end
    end

    enumeration
        BLACK     (  0,   0,   0)
        BLUE      (  0,   0, 255)
        GREEN     (  0, 255,   0)
        CYAN      (  0, 255, 255)
        RED       (255,   0,   0)
        MAGENTA   (255,   0, 255)
        YELLOW    (255, 255,   0)
        WHITE     (255, 255, 255)
   end
end

red = Color.RED
gray1 = Color(128, 128, 128)
gray2 = Color("#808080")

History

Version	Description
2026.0.0	`classdef` introduction.

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