Question

I’m coding in an embedded language called JS.

I want to be able to call three functions in any order. (ABC, ACB, BAC, BCA, CBA, CAB.)

The trick? The language doesn’t have user-defined functions.

It does have a conditional and a looping construct.

I think I have three choices.

1. Duplicate a whole bunch of code.
2. Write a preprocessor (that would create all the duplicated code).
3. Do a loop with three iterations, using an array to control which functionality gets called on each pass of the loop.

I hate #1. Duplicated code is nasty. How do I change anything without screwing up?

I guess #2 is OK. At least I don’t have duplicated code in the source. But my output code is what I’ll be debugging, and I wonder if I want to diverge from it. On the plus side, I could add a bunch of sugar to the language.

I think my best bet is #3.

Any other ideas? There is no goto. No functions. No existing preprocessor.

Funny thing about #3 is that it’s essentially the infamous for/switch nightmare.

Answer 1

Perhaps some kind of mutant state-machine, viz:

int CODEWORD=0x123;

while (CODEWORD)
{
    switch(CODEWORD&15)
    {
    case 1:
       /// case 1
       break;
    case 2:
       /// case 2
       break;
    case 3:
       //// case 3
       break;
    }
    CODEWORD=CODEWORD>>4;
}

DRY, no preprocessor, no array. for/switch seems somewhat unavoidable.