Displaying Progress Status of Long Running Script, Part 4: Display-Erase Utility

Posted by Stuart McGarrity, August 17, 2016

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Sometimes when displaying the progress of a long running script, there is so much output at the command window that there is too much to scroll through or the buffer fills up and you can’t go back to see full the history.

In this code-along style video I write a utility, based on my colleague Sean’s suggestion that displays new status information after erasing the previous information. This allows progress to displayed without filling up the command window.

Features used in this video include:

Displaying characters and strings
Storing state with nested functions

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Function is here:


function f=makeEraseDisplayFunction

% Length of last string
len=0;

% Return handle to function
f = @displayFunction;

% Nested Function
    function displayFunction(str,varargin)
        
        if nargin>=2
            eraseThisTime=varargin{1}; % True or false
            if ~eraseThisTime
                len = 0;
            end
        end
        
        % Erase previous characters
        eraseStr=repmat('\b',[1 len] );
        fprintf(eraseStr);
        
        % Display New characters
        fprintf(str);
        
        % Decide what to do at next call
        if nargin == 3
            eraseNextTime=varargin{2}; % True or false
            
            if eraseNextTime
                len = length(str);
            end
            len = 0;
        else
            len = length(str);
        end
    end
end