I use it quite often in my graphics routines. Sometimes I just modify immediate values, other times I will modify the actual instructions being executed (for example, rotating A by any amount can be done in 4 instructions or less). Other than graphics, I don't use much SMC because most of my major projects are now APPs.

Yeah, SMC is mainly for speed gains impossible with normal techniques. It is also useful as a tool to prevent people from understanding your programs.
Also for forcing instructions to have more options than normal (bit, set, and res, for example)

It can also be useful if you want to keep your game in one file, even when using save/load options built in the game

Though, that's not really self-modifying code, it's modifying data.

Mmm i like programs that use SMC for highscores ^^ It makes the appvar space less cluttered

My main worry about appvars is that we're more prone to accidentally delete it or lose it in a RAM clear, and I'm not too fond of the idea of archving my appvars everytime I exit my game, especially if the appvar is very large

Hey, the results kind of look like a bell curve.
Not surprising, at any rate.
Yeah, when I said SMC, I wasn't referring to saving data w/in the program itself. The only thing I don't like about that technique (it is, for the most part, good, like others have said) is that I have to have write-back for archived programs turned on. (I try not to use my archive too much, but the programmers are against me! )

I will only start using SMC when I need speed.
Not using SMC keeps compatibility with APPS and is much more reusable code for other projects (like OSes or other APPS).


I see some confusion between SMC (Self Modifying Code) and write-back on Omnimaga forums. Not only on this topic. I will try to differentiate them.

SMC is when code will simply modify some other code.
Only possible when the code is in RAM so it is easily changed like normal data. The modified code is temporary. (true for 99% of cases) So very rarely if ever SMC needs write-back for the program to work as expected.

Write-back is writing the "copy" back to the "original" program.
This happens because the assembly programs you run is not the original but a copy in a address equated as userMem (address $9D95). For example, in the end of the program data resides the save game data. In order to the program work as expected and your precious progress be kept you need some additional code (it finds out the position of the original program and copies the data back to it) or a shell with write-back option that does the job for the coder.

Note that SMC and write-back are independent. But generally data needs write-back and SMC do not.
If I made a mistake or was not clear, please point out, no one is perfect.

EDIT: bonus example

Mmm i like programs that use SMC for highscores ^^ It makes the appvar space less cluttered

It is correctly write-back and not self modifying code. You are modifying some data of a highscore, not code and you need that is copied back to the original program.
(curiously you can hard code high score data into code but is very rare and not the best way to store this kind of data)
EDIT: Oh, but if you are talking about Axe Parser, it is possible you are using both SMC and write-back.