,---------------.
| Contributions |
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,------------------------------------------
| 2016-06-18 04:19:03  enoch  wrote:
| proposal - WLSCOPE -- wordlists switching made easier
| see: https://forth-standard.org/proposals/wlscope-wordlists-switching-made-easier#contribution-20
`------------------------------------------
Proposal
========

It is proposed that Forth 200x compliant implementations would be required
to offer a deferred word, *wlscope (addr len -- addr' len' wid)*, whose
initial implementation *is get-current*. All the mechanisms that create new
dictionary entries would be required to pass the new name *( addr len )*
through *wlscope* to obtain the destination wordlist *( wid )*; the name
itself may also be altered, hence *( addr' len' )*.

Problem
=======

Make it easier to manage inclusion of created words on different
wordlists. All large software projects carefully regulate their name
spaces. Openfirmware, for example, to separate between the "public" words
and the "private" words often groups them as follows:

    only forth also hidden also definitions
    ...
    also forth definitions
    ...

With *wlscope* we would like to take this one step further and allow
**wordlist switches to be driven by the new name itself**, in a way that is
completely under the programmer control, through a chain of user defined
wlscope functions which analyze and perhaps modify the newly created name
and determine to which wordlist it is to be added.

Typical use
===========

The following shows two wlscope "rules" and how to chain them.

Put helper (factorization) words onto a *_local* wordlist
---------------------------------------------------------

    \ Wordlist scope that puts words with underscore (_) prefix
    \ on a _local wordlist.
    
    :noname  ( addr len -- addr' len' wid ) 
       2dup
	      1 >  if				        \ name length check
          s" _" tuck icompare  if		\ name prefix check
    	_local exit
          then
       else
          drop
       then
       [ ' wlscope defer@ ]l execute
    ; is wlscope

Grow a special use *gui* wordlist
---------------------------------

    vocabulary gui 
    
    :noname  ( addr len -- addr' len' wid ) 
       2dup
       4 >  if				            \ name length check
          s" gui_" tuck icompare  if	\ name prefix check
    	swap 4 + swap 4 -		        \ remove gui_ prefix
    	gui exit
          then
       else
          drop
       then
    
       [ ' wlscope defer@ ]l execute
    ; is wlscope


Thus,

    : _helper ... ;

would automatically add *_helper* to the *_local* wordlist while

    : gui_init-gl ... ;

would add *init-gl* to the *gui* wordlist.

Reference Implementation
========================

[amforth-shadow](https://github.com/wexi/amforth-shadow)

VM asm code at: core/create/docreate.asm and elsewhere.

Experience
==========

amforth and amforth-shadow



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| Replies |
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,------------------------------------------
| 2016-05-24 13:27:38  AntonErtl  replies:
| comment - TRAVERSE-WORDLIST is in the wrong word set
| see: https://forth-standard.org/standard/tools/TRAVERSE-WORDLIST#reply-22
`------------------------------------------
Yes, the search order wordset might have been a better place.  However, given that TRAVERSE-WORDLIST is in Forth-2012 is in the TOOLS wordset, and there is little point in changing that (given that we don't have wordset queries for Forth-2012, it has no effect on programming).  Also, the NAME>... words from the same proposal have nothing to do with the search-order wordset; should we distribute the words from this proposal over several wordsets?


,------------------------------------------
| 2016-05-24 13:35:32  AntonErtl  replies:
| testcase - Another use of UNLOOP
| see: https://forth-standard.org/standard/core/UNLOOP#reply-23
`------------------------------------------
Do we want to limit the Forth implementations to those that are implemented in the way you describe?  I don't.

Anyway, don't let my objections stop you.  If you think it is worth it, make a [proposal](http://forth-standard.org/standard/process).