How to underline an undefined function or variable

Hi,

I am curious if there is a way to configure Matlab to show an undefined function or variable before running a script. For example, I want the following code to be executed if variable "a" is defined, otherwise I get notification that "a" is not set before pressing "F5".

 if a>1
   b=2;
 end

Is there a way to configure this, maybe in Matlab code analyzer?

[Stephen23]

It is easy for code to change the MATLAB Search Path while running, to run scripts and call functions which change/define/clear variables in the workspace, and to overload almost any operator. There is no way to know what code will resolve to and what variables it actually has, until it is run.

That is simple a side effect of a dynamically typed language which is parsed on the fly. It is in the very nature of such a language.

[Heorhii Koltsov]

I read that there is pylint for Python which is checking the code statically and I think it will also check for the variables

Answer 1

[John D'Errico]

I believe that capability would not exist, because it is easy enough to create a variable or function name on the fly. It would be terribly poor coding practice to do so, but you CAN do it.

A quick check in the editor preferences did not show such a flag.

Answer 2

[Image Analyst]

There is a not very practical way. You could do

if exist('a', 'var')
  if a>1
    b=2;
  end
else
  uiwait(errordlg('a does not exist'));
end

But you really don't want to do that for every variable in your program. Anyway, if you knew to check for it, then you'd know to assign it. There is no automatic way to do it before running your program. However sometimes the mlint will tell you that a variable is being used before it's assigned with a orange squiggly underline, but it doesn't always detect that.

[Heorhii Koltsov]

Yeah that's correct. I read about exist function but of course it would be painful to write it for each variable. I guess the problem is that I am not using matlab correctly that's why I have such question :)