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Set default values

version 1.0.0.0 (1.32 KB) by Richie Cotton

Richie Cotton (view profile)
A very simple function that initialises a missing or empty value in the caller function.
5.0
3 Ratings

2 Downloads

Updated 23 Mar 2010

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Editor's Note: This file was selected as MATLAB Central Pick of the Week

In order to set default values for variables, I find the start of my functions littered with

if nargin < 1 || isempty(x)
x = 1;
end

if nargin < 2 || isempty(y)
y = 3;
end
etc.

This is pretty ugly, so I've created a wrapper to prettify it. Honestly, it's so simple that I nearly didn't upload this, but it does make your functions cleaner. Now the above is transformed to

SetDefaultValue(1, 'x', 1);
SetDefaultValue(2, 'y', 3);

Note that there are other ways to set defaults. See
http://blogs.mathworks.com/loren/2009/05/05/nice-way-to-set-function-defaults/

Cite As

Richie Cotton (2020). Set default values (https://www.mathworks.com/matlabcentral/fileexchange/27056-set-default-values), MATLAB Central File Exchange. Retrieved .

Comments and Ratings (4)

Terry

Terry (view profile)

Sorry, you still need to do the "evalin" trick
~evalin('caller', ['exist(''' argName ''', ''var'')']) || ...

Terry

Terry (view profile)

@Marco, I ran into the same thing. I just modified the condition so that it tests for the variable's existence before trying to access it.

~exist(argName,'var') || ...

Added before the 'isempty(...' line

Marco Celesti

Marco Celesti (view profile)

Thanks to the author for this useful function. I've used it with no problem with Matlab up to R2016a, with this release I get an error like this:

Error using evalin
Undefined function or variable 'a'.

Error in SetDefaultValue (line 19)
isempty(evalin('caller', argName))

Error in pippo (line 4)
SetDefaultValue(1,'a',1)

when executing a dummy function "pippo":

function [ c ] = pippo( a, b )
%PIPPO Summary of this function goes here
% Detailed explanation goes here
SetDefaultValue(1,'a',1)
SetDefaultValue(2,'a',4)

c = a*b;

end

How should I fix it to get it working with R2016a (and possibly back compatible)?
Thanks a lot,

Marco

David Young

David Young (view profile)

MATLAB Release Compatibility
Created with R2009b
Compatible with any release
Platform Compatibility
Windows macOS Linux
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