BASIC routine identity

Here’s an interesting bug that I have not seen mentioned in 30 and more years of using BASIC.

The rules for routine (PROC/FN) identities differ from variables. Among these is that ‘@’ can be used as well as alphanumeric characters. Using ‘@’ has its own peculiarities, which I had to deal with when writing that BASIC parser a while back. This is different, though, and I came across it when stretching what I might do with BASIC.

I had two routine definitons with names that only differ with an ‘@’ at the end of one, like this:

DEFPROCtest:PRINT 1:ENDPROC
DEFPROCtest@:PRINT 2:ENDPROC

All was fine. Then I reversed the position of the definitions in the program:

DEFPROCtest@:PRINT 1:ENDPROC
DEFPROCtest:PRINT 2:ENDPROC

Now, when calling PROCtest there is a ‘Syntax error’ or ‘Arguments of function/procedure incorrect’ if there are parameters.

I think I can see what is happening, but I have not checked the source.

I think the lesson is to avoid ‘@’ in routine names. ;-)

The kind of peculiarity that normal people (if that’s a description that’s even remotely appropriate for any of us here) never discover because they never think of using @ in routine names, never realize it’s allowed…

I could see that affecting BASIC compressors which reduce PROC/FN names to as few characters as possible, including non-alphanumerics. I suspect it hasn’t been seen as PROCa would be used before PROCa@.