Re: Learning RPG IV advanced techniques

I love inaccurately commented code!

As I was reading this, some old brain cells sparked and I remember that there was a specific syntax in EDL, GOTO *, that was INTENDED to be overwritten.  You put a label on the statement (MYGOTO: GOTO *) and then you change MYGOTO+2 to be the address where you really wanted to jump.

Oh my yes, that was fun!


On 11/7/2020 11:31 AM, Jon Paris wrote:

The S/36 RPG compiler was written in Assembler and did a lot of on-the-fly code changing. Spent days trying to debug a problem one time only to discover that you should never trust comments! The bit pattern being applied to modify the instruction did not do what the writer said it did!

On Nov 7, 2020, at 12:26 PM, Joe Pluta <joepluta@xxxxxxxxxxxxxxxxx> wrote:

My favorite language is probably still EDL for the Series/1. If you changed *-2, you were actually changing the PROGRAM CODE. That's how we did poor man's recursion. Ah, those were the days.

On 11/6/2020 3:37 PM, James H. H. Lampert wrote:

On 11/6/20 1:05 PM, Alan Campin wrote:

I have been corrected. Pascal and Modula 2 do support pointers. They are
just "type" safe. C and RPG pointers are not type safe. They can point to
anything.

The same is true of PL/I pointers. And of course, pointers in (LISP).

Pointers originated in PL/I. Not only did PL/I (1964) predate C (1972); it also predated B (1969) and BCPL (1967).

--
JHHL

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