Re: QUIT and ABORT

On 2025-05-05 08:11, dxf wrote:

On 4/05/2025 11:33 pm, Anton Ertl wrote:

...
Here's the code I give to the Forth systems:
>
1 .( a ) cr -56 throw .( b )
.s
2 .( a ) cr quit .( b )
.s
: foo 3 -56 throw ; ' foo catch 5
.s
: bar 4 quit ; ' bar catch 6
.s
>
Let's see what different Forth systems do:
...

 In DX-Forth QUIT is not CATCHable thus -56 THROW simply returns:
    a
     THROW #-56
 However modifying it to do so gives these results:
 1 .( a ) cr -56 throw .( b )
    'a' is displayed and the stack is: 1

This violates the behavior of `throw` specified in 9.6.1.2275,
because if there is no a user's exception frame, the data stack must be emptied.
The table 9.1 in Forth-2012 (or 9.2 in Forth-94) does not affect the behavior of `throw` at all.
Your implementation will probably fail the following test case:
   t{ 123 [: 999 -56 throw ;] catch 456 -> 123 -56 456 }t

 2 .( a ) cr quit .( b )
    'a' is displayed and the stack is: 2
 : foo 3 -56 throw ; ' foo catch 5
    stack is: -56 5

These cases are standard-compliant.

 : bar 4 quit ; ' bar catch 6
    stack is: -56 6
 

This violates `quit` 6.1.2050, because:
   - `quit` is not allowed to remove anything from the data stack (in this case, remove 4 from the stack);
   - `quit` is not allowed to place anything on the data stack (in this case, place `-56`);
   - `quit` is not allowed to interpret the remaining part of the input buffer  (in this case, interpret "6" and place 6 on the stack).
--
Ruvim