When you call functions , you need to write a text , why not add an option for a drop menu with all the already created functions ? There'll be less chances of error and better arrangment possibilities when you are flooded with functions ...
Well that's part of the deal with functions. You get a value you can change on the fly, sort of like the ability to create variables without declaring them first. Actually, doing a variable comparison is a lot closer to what you described.
Whenever I create a function, I always save its name to a source, like an array, variable, xml file, etc. That way, I can reference that source whenever the function needs to be called so I avoid issues like this.
There was an idea on another thread to have comboboxes for several kind of objects where possible Pick from the dropdown list, or stick with the possibility dynamic expressions... best of the two worlds