16.6.1.2197 SET-ORDER SEARCH

( wid_n ... wid₁ n -- )

Set the search order to the word lists identified by wid_n ... wid₁. Subsequently, word list wid₁ will be searched first, and word list wid_n searched last. If n is zero, empty the search order. If n is minus one, set the search order to the implementation-defined minimum search order. The minimum search order shall include the words FORTH-WORDLIST and SET-ORDER. A system shall allow n to be at least eight.

Implementation:

This is the complement of E.16.6.1.1647 GET-ORDER.

: SET-ORDER ( wid1 ... widn n -0 )
   DUP -1 = IF
     DROP <push system default word lists and n>
   THEN
   DUP #order !
   0 ?DO I CELLS context + ! LOOP
;

Testing:

T{ GET-ORDER OVER -> GET-ORDER wid1 @ }T
T{ GET-ORDER SET-ORDER -> }T
T{ GET-ORDER -> get-orderlist }T T{ get-orderlist DROP get-orderList 2* SET-ORDER -> }T
T{ GET-ORDER -> get-orderlist DROP get-orderList 2* }T
T{ get-orderlist SET-ORDER GET-ORDER -> get-orderlist }T

: so2a GET-ORDER get-orderlist SET-ORDER ;
: so2 0 SET-ORDER so2a ;

T{ so2 -> 0 }T \ 0 SET-ORDER leaves an empty search order

: so3 -1 SET-ORDER so2a ;
: so4 ONLY so2a ;

T{ so3 -> so4 }T \ -1 SET-ORDER is the same as ONLY

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LeonWagner [164] Typo in stack commentComment2020-11-04 17:07:33

The extra 0 at the end of this stack comment looks like a typo: : SET-ORDER ( wid1 ... widn n -0 )

Should be: : SET-ORDER ( wid1 ... widn n -- )

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lmr [320] Negative n values Request for clarification2023-12-19 22:16:40

If n is negative and <= -2, is it ambiguous, or a mandatory error? E.g. can I use "-2 SET-ORDER" to allow the user (as well as system primitives) to reset the search order to the default of my implementation?

AntonErtl [r1144] 2023-12-20 07:41:02

It's not specified, so systems can do whatever they want. Giving it some sane behaviour, as you suggest, appears to be a good idea.

Checking three systems, I see

gforth 0.7.3 does not produce an error, but the resulting search order does not include order or set-order (and is probably corrupt, word completion produces an "invalid memory address" throw).
SwiftForth 4.0.0-RC52 exits with a Segmentation fault.
VFX Forth 64 5.11 RC2 appears to handle -2 set-order in the same way as -1 set-order.

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