setup

One-time set up tasks for System objects

Syntax

setup(obj)

setup(obj,input1,...,inputN)

Description

setup(obj) performs one-time setup tasks specific to the System object™.

setup(obj,input1,...,inputN) performs one-time setup tasks when those setup tasks require sample inputs to validate input values.

Examples

Initialize Counter System Object

This example shows how to call setup on a System object™. In most cases, you do not need to call setup directly because setup initialization happens the first time you run your System object. Call setup before running only if you have concerns about the execution time of initialization.

Create a System object Counter with a start value of 5. (See the full definition of Counter in the section below.)

count = Counter('StartValue',5)

count = 
  Counter with properties:

    UseIncrement: true
    UseWrapValue: true
      StartValue: 5
       Increment: 1
       WrapValue: 10

In the definition of the Counter object, setupImpl initializes the StartValue property with the specified number at which to start counting. When you call setup, the System object calls setupImpl and also validates the input and property values. Because Counter has defined these internal validation methods, you must give setup an input value to validate.

Initialize the StartValue for your count object by calling setup with a placeholder input value. After initialization, run the object.

setup(count,0)
count(2)

ans = 
7

Full Definition of the Counter System Object

type Counter.m

classdef Counter < matlab.System
% COUNTER Compute an output value by incrementing the input value
  
  % All properties occur inside a properties declaration.
  % These properties have public access (the default)
  properties
    UseIncrement (1,1) logical = true    % Use custom increment value.
    UseWrapValue (1,1) logical = true    % Use max value.
    
    StartValue (1,1) {mustBeInteger,mustBePositive} = 1   % Value to start from.
    Increment (1,1) {mustBeInteger,mustBePositive} = 1    % What to add to Value every step.
    WrapValue (1,1) {mustBeInteger,mustBePositive} = 10   % Max value to wrap around.
  end

  properties(Access = protected)
      Value
  end

  methods
    % Constructor - Support name-value pair arguments when constructing object
    function obj = Counter(varargin)
        setProperties(obj,nargin,varargin{:})
    end

    function set.Increment(obj,val)
        if val >= 10
          error('The increment value must be less than 10');
        end
        obj.Increment = val;
    end
    
  end
  
  methods (Access = protected)
    % Validate the object properties  
    function validatePropertiesImpl(obj)
        if obj.UseIncrement && obj.UseWrapValue && ...
                (obj.WrapValue < obj.Increment)
          error('Wrap value must be greater than increment value');
        end
    end
    
    % Validate the inputs to the object
    function validateInputsImpl(~,x)
        if ~isnumeric(x)
          error('Input must be numeric');
        end
    end
    
    % Perform one-time calculations, such as computing constants
    function setupImpl(obj)
        obj.Value = obj.StartValue;
    end
  
    % Step
    function out = stepImpl(obj,in)
      if obj.UseIncrement
        % If using increment property, multiple the increment by the input.
        obj.Value = in*obj.Increment + obj.Value;
      else
         % If not using increment property, add the input.
        obj.Value = in + obj.Value;
      end
      if obj.UseWrapValue && obj.Value > obj.WrapValue
         % If UseWrapValue is true, wrap the value
         % if it is greater than the WrapValue.
         obj.Value = mod(obj.Value,obj.WrapValue);
      end
      out = obj.Value;
    end
  end
end

Examples in Other Toolboxes

• Reduce Latency Due to Input Device Buffer (Audio Toolbox)

• Byte Transmission Using UDP (DSP System Toolbox)

Input Arguments

obj — System object to set up

System object

System object you want to set up before running the System object.

Alternative Functionality

For most System objects, you do not need to call setup. When you call the System object for the first time, setup is called. (See Summary of Call Sequence.) You should call setup separately only if you need to reduce the computational load of initialization.

Version History

Introduced in R2010a