Here is your example using Leo Brodie's DOER/MAKE with real code in place of some-code and code-for-another-handler .

And here is a log of when it is loaded and executed. The computer's responses are in italics.

4D LOAD OK
SELECTOR-B OK
HANDLER-A STACK EMPTY OK
SELECTOR-B THIS HAS NO NAME. OK

And no, a new version is not compiled each time HANDLER-A is run.

To give you an example of what's possible with DOER/MAKE , here is an example from "Thinking Forth".

And here is a sample run.


Cheers,
Jim

Hah, brilliant example Thanks, that looks like exactly what I was looking for.

As I said, the example is straight out of "Thinking Forth". It's in Appendix B where Leo Brodie explains how DOER/MAKE works and gives implementations for various Forth systems. I don't think any of them were subroutine threaded systems though. I don't know if the Forth you're using is ITC ( indirect threaded ), DTC ( direct threaded ), or STC ( subroutine threaded ), or possibly some other threading technique. I successfully ported DOER/MAKE to my Forth, Fleet Forth for the Commodore 64, a short while ago. It's an ITC Forth. Last night I took a look at Durex Forth for the Commodore 64. It appears to use subroutine threaded code. I managed to port DOER/MAKE to it. Be warned! it has had minimal testing! That said, it should work with other subroutine threaded Forths for the 6502 based processors. Maybe someone using Tali Forth or Liara Forth could test it?

If you've had time to read "Thinking Forth", you'll notice one ability that's missing. The ability to use MAKE outside a colon definition to create an unnamed section of high level code that the DOER word performs. That ability is not needed in the examples I've shown and it would require knowledge of how a given system implements : ( colon) and ; ( semicolon).

Cheers,
Jim

[Edit: Corrected two typos.]

It works on Tali, but I had to put a "T" in POSTPONE in two spots and add a definition for 2+. Here's the version that works on Tali Forth 2:




One oddity is that the " ok" message was missing after each run, leaving the cursor just after the printed message but accepting new input. It looks like the OK message is similarly missing in the example from Thinking Forth that JimBoyd showed a few posts back. Tali doesn't normally print carriage returns at the end of a string, so the new "why?" that I typed ended up on the end of each message, but the doer/make behavior seems to be working properly.

The missing " ok" message is because of the QUIT in WHY?. Sneaking an extra CR in there makes it work identically to the Thinking Forth version.

I changed why? to:

and now it works like:

Oops. I just fixed my typos. I already had DOER/MAKE working on Fleet Forth, an ITC Forth. I didn't know what Forth commodorejohn was using so I ported it to Durex Forth for the Commodore 64 which appears to be an STC Forth. I got frustrated with the Durex editor, specifically how to get out of insert mode and back to the Forth interpreter, so I entered the code interactively. I copied the working code to a text file by hand and somehow missed the 'T' in POSTPONE in both places!