Documentation

The Standard Set/Get Interface

Some MATLAB^® objects, such as graphics objects, implement an interface based on set and get functions. These functions enable access to multiple properties on arrays of objects in a single function call.

You can add set and get functionality to your class by deriving from one of these classes:

Subclass Syntax

Use the abstract class matlab.mixin.SetGet or matlab.mixin.SetGetExactNames as a superclass:

classdef MyClass < matlab.mixin.SetGet
   ...
end

Because matlab.mixin.SetGet and matlab.mixin.SetGetExactNames derive from the handle class, your subclass is also a handle class.

Get Method Syntax

The get method returns the value of an object property using the object handle and the property name. For example, assume H is the handle to an object:

v = get(H,'PropertyName');

If you specify an array of handles with a single property name, get returns the property value for each object as a cell array of values:

CV = get(H,'PropertyName');

The CV array is always a column regardless of the shape of H.

If you specify a cell array of char vector property names and an array of handles, get returns a cell array of property values. Each row in the cell corresponds to an object in the handle array. Each column in the cell corresponds to a property name.

props = {'PropertyName1','PropertyName2'};
CV = get(H,props);

get returns an m-by-n cell array, where m = length(H) and n = length(props).

If you specify a handle array, but no property names, get returns an array of type struct in which each structure in the array corresponds to an object in H. Each field in each structure corresponds to a property defined by the class of H. The value of each field is the value of the corresponding property.

SV = get(H);

If you do not assign an output variable, then H must be scalar.

For an example, see Using get with Arrays of Handles.

Set Method Syntax

The set method assigns the specified value to the specified property for the object with handle H. If H is an array of handles, MATLAB assigns the value to the property for each object in the array H.

set(H,'PropertyName',PropertyValue)

You can pass a cell array of property names and a cell array of property values to set:

props = {'PropertyName1','PropertyName2'};
vals = {Property1Value,Property2Value};
set(H,props,vals)

If length(H) is greater than one, then the property value cell array (vals) can have values for each property in each object. For example, suppose length(H) is 2 (two object handles). You want to assign two property values on each object:

props = {'PropertyName1','PropertyName2'};
vals = {Property11Value,Property12Value;Property21Value,Property22Value};
set(H,props,vals))

The preceding statement is equivalent to the follow two statements:

set(H(1),'PropertyName1',Property11Value,'PropertyName2',Property12Value)
set(H(2),'PropertyName1',Property21Value,'PropertyName2',Property22Value)

If you specify a scalar handle, but no property names, set returns a struct with one field for each property in the class of H. Each field contains an empty cell array.

SV = set(h);

Class Derived from matlab.mixin.SetGet

This sample class defines a set/get interface and illustrates the behavior of the inherited methods:

classdef LineType < matlab.mixin.SetGet
   properties
      Style = '-'
      Marker = 'o'
   end
   properties (SetAccess = protected)
      Units = 'points'
   end
   methods
      function obj = LineType(s,m)
         if nargin > 0
            obj.Style = s;
            obj.Marker = m;
         end
      end
      function obj = set.Style(obj,val)
         if ~(strcmpi(val,'-') ||...
               strcmpi(val,'--') ||...
               strcmpi(val,'..'))
            error('Invalid line style ')
         end
         obj.Style = val;
      end
      function obj = set.Marker(obj,val)
         if ~isstrprop(val,'graphic')
            error('Marker must be a visible character')
         end
         obj.Marker = val;
      end
   end
end

Create an instance of the class and save its handle:

h = LineType('--','*');

Query the value of any object property using the inherited get method:

get(h,'Marker')

ans =

*

Set the value of any property using the inherited set method:

set(h,'Marker','Q')

set(h,'Style','-.-')

Error using LineType>LineType.set.Style
Invalid line style

h = LineType('--','*');
SV = get(h)

SV =

     Style: '--'
    Marker: '*'
     Units: 'points'

S = set(h)

S =

     Style: {}
    Marker: {}

H = [LineType('..','z'),LineType('--','q')]

H = 

  1x2 LineType with properties:

    Style
    Marker
    Units

CV = get(H,'Style')

CV = 

    '..'
    '--'

SV = get(H)

SV = 

2x1 struct array with fields:
    Style
    Marker
    Units

SV(2).Marker

ans =

q

H = [LineType('..','z'),LineType('--','q')];
set(H,{'Style','Marker'},{'..','o';'--','x'})

H(1)

ans = 

  LineType with properties:

     Style: '..'
    Marker: 'o'
     Units: 'points

H(2)

ans = 

  LineType with properties:

     Style: '--'
    Marker: 'x'
     Units: 'points'