deleting a certain variable in the base workspace via a function

hi, assume i have the variable x in the base workspace.

I want to delete that variable x via a function. How can I accomplish this?

thanks

[Stephen23]

Messing around with other workspaces is a design flaw.

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

[Vassilis Lemonidis]

Design flaws and scripts (workspaces) do not go along in general, so personally I do not consider the above a valid argument. Also, let me reverse the argument. Eg. let's say you have a function saveInChunks that saves a huge variable, created by let's say a matrices product or any other convolved operation, in chunks, to pass it to parfor workers, and then deletes the variable. This cannot be implemented anywhere outside of the main script that creates the variable in the first place. That is a design flaw, of Matlab. Unfortunately, to my knowledge, the only way to handle such a situation is by using evalin , which is an intrinsically unsafe operation, or well, make classes and have to face all the backwards compatibility issues and caveats, without live debugging.

[Steven Lord]

If you've written one function that interacts with a different workspace than its own, what guarantee do you have that you don't have two functions that are both trying to interact with that different workspace? If the first of those functions deletes or modifies data that the second of those functions needs to use, that first function could break the second function (and if it just modifies the data rather than deleting it, that "break" could be a change in the behavior of that second function that gives no indication the behavior has changed rather than an error. Those can be very difficult and time consuming to debug.)

Answer 1

[per isakson]

Try

    evalin( 'base', 'clear(''x'')' )

and simpler

    evalin( 'base', 'clear x' )

But take the advice of Image Analyst seriously

[Will Reeves]

being pedantic, "deleting" and "clearing" are different things in Matlab... Be careful which one is choosen!

Specifically, when "deleteing" instances of classes that have a "destructor" method, "clear" will not trigger it and could leave you with issues. In that case "delete" must be called first (which triggers the delete method), then "clear" which cleans up the handle to the class instance.

Answer 2

[Image Analyst]

That would not be necessary. It's not good practice to have functions messing around with variables in other workspaces than their own.

[Sean de Wolski]

If you need to save something to the base workspace and thus want to clear what's there, look at export2wsdlg. This helps the user not mess anything up.

Answer 3

[dpb]

doc evalin