Unable to run cell with variable-setting macro twice

[cadojo]

Some packages (MATLAB, ModelingToolkit) use macros for setting variables.

• MATAB uses @mget x to copy a Matlab workspace variable x into a Julia variable called x.

• ModelingToolkit uses @variables x y z to initialize symbolic variables x, y, and z.

In Pluto v0.11.12 (and all other versions I've used), you can't run any cell with either of these macros more than once.

Take ModelingToolkit's @variables as an example. If a cell contains:

@variables x

It will run correctly once. If the cell is run again, it produces the following error:

cannot assign a value to variable workspace24.x from module workspace25

The current workaround is to set x to nothing before calling @variables x in the same cell. It seems that a new module is created every time a cell is run. We probably only care about the latest module, right? Would it be possible to "forget" about modules 1 through 24 in this example?

[fonsp]

Thanks! Have a look at #196

[fonsp]

You're right that forgetting about all unrecognized variables from previous workspace modules would fix the problem that you can't assign twice, but it will introduce a new problem: the variable only exists for one reactive run, and is forgotten afterward. This makes the macro even less useful 😥