Overwrite mata function

[Frank Erickson]

I have some helper functions in a separate script that I `source` from other scripts. It may happen, especially when working interactively, that I source/define the function even though it already exists. I'd like to add a line like mata: capture drop function_name() ahead of the function definition, but there is no capturing in Mata.

mata:
function f(){
    return(1)
}
end

** do some stuff
** remove function or maybe don't

** later, want to make sure the function is available

<<< What can I insert here? >>>

mata:
function f(){
    return(1)
}
end

Other ideas besides capture:

mata: mata drop f()

This fails when the function does not exist.

mata:
if (findexternal("f()") != NULL){
    mata drop f()
}
end
mata:
function f(){
    return(1)
}
end

This fails because Mata/Stata is declarative and doesn't like contingent drops ... or something.

mata:
if (findexternal("f()") == NULL){
    function f(){
        return(1)
    }
}
end

This fails because Mata/Stata is declarative and doesn't like contingent definitions ... or something.

I got the idea for these latter two from another thread. A 2008 thread seems very closely related, but I can't figure out what is going on in it.

[Jesse Wursten]

You can "cheat" by using

cap mata mata drop function_name()

The capture is still in the Stata environment, meaning the code will continue even if there's nothing to drop in mata

[Frank Erickson]

Yeah, I think that's the ticket. Thanks, Jesse! I just found that with a minute's more googling; turns out it was elsewhere in the last thread I linked.