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Groups > comp.lang.forth > #41103

Re: RFD: Quotations V2 update

From Bernd Paysan <bernd.paysan@gmx.de>
Newsgroups comp.lang.forth
Subject Re: RFD: Quotations V2 update
Date 2015-08-04 22:00 +0200
Organization A noiseless patient Spider
Message-ID <mpr5ic$lst$1@dont-email.me> (permalink)
References <mpq2n2$85u$1@dont-email.me>

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Alex McDonald wrote:

> There are two schools of thought.
> 
> 1. Define [: ;] such that a standard program may not access
> local variables of the outer definition inside the quotation.
> 
> 2. Permit such a feature, but restrict valid execution of the
> quotation to the lifetime of the parent's execution.

I've found more problems with 2.  A lot of my quotation use (especially in 
MINOS) requires that the quotation outlives the lifetime of the parents.

Essentially, I create objects with actions attached (action = xt).  So the 
object initialization takes one or more xts.  These xts are quotations.  If 
we allow access to outer locals via local frames, we, at the same time, 
would disallow this use, because the local frame dies when the creator of 
the quotation exits (unless it is a real closure)

Typical use comes from converting Leo Brodie's DOER MAKE examples into 
DEFER/IS/quotations examples:

Defer type  ( a # -- )
: video   [: ( ...code for video...) ;] is type ;
: printer [: ( ...code for printer...) ;] is type ;

This only works if the quotation outlives its surrounding definition.  So it 
has to be either a real closure (with garbage collection and everything) if 
it can access outer locals, or it may not access outer locals.

I'm not against real closures, but would strongly advice *not* to use the 
normal locals and quotation syntax for closures.

-- 
Bernd Paysan
"If you want it done right, you have to do it yourself"
net2o ID: kQusJzA;7*?t=uy@X}1GWr!+0qqp_Cn176t4(dQ*
http://bernd-paysan.de/

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RFD: Quotations V2 update "Alex McDonald" <blog@rivadpm.com> - 2015-08-04 11:05 +0100
  Re: RFD: Quotations V2 update Mark Wills <markwills1970@gmail.com> - 2015-08-04 04:09 -0700
    Re: RFD: Quotations V2 update Lars Brinkhoff <lars.spam@nocrew.org> - 2015-08-04 13:35 +0200
      Re: RFD: Quotations V2 update "Alex McDonald" <blog@rivadpm.com> - 2015-08-04 13:54 +0100
        Re: RFD: Quotations V2 update "Alex McDonald" <blog@rivadpm.com> - 2015-08-04 14:01 +0100
    Re: RFD: Quotations V2 update "Alex McDonald" <blog@rivadpm.com> - 2015-08-04 13:38 +0100
      Re: RFD: Quotations V2 update Mark Wills <markwills1970@gmail.com> - 2015-08-04 07:37 -0700
  Re: RFD: Quotations V2 update anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-08-04 14:23 +0000
    Re: RFD: Quotations V2 update "Alex McDonald" <blog@rivadpm.com> - 2015-08-04 16:09 +0100
      Re: RFD: Quotations V2 update anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-08-04 15:38 +0000
        Re: RFD: Quotations V2 update Bernd Paysan <bernd.paysan@gmx.de> - 2015-08-04 22:30 +0200
          Re: RFD: Quotations V2 update "Alex McDonald" <blog@rivadpm.com> - 2015-08-04 23:09 +0100
            Re: RFD: Quotations V2 update Bernd Paysan <bernd.paysan@gmx.de> - 2015-08-05 01:45 +0200
              Re: RFD: Quotations V2 update anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-08-05 07:23 +0000
                Re: RFD: Quotations V2 update "Alex McDonald" <blog@rivadpm.com> - 2015-08-05 09:55 +0100
          Re: RFD: Quotations V2 update Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-08-05 12:03 +0100
            Re: RFD: Quotations V2 update "Alex McDonald" <blog@rivadpm.com> - 2015-08-05 13:50 +0100
              Re: RFD: Quotations V2 update anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-08-05 16:07 +0000
              Re: RFD: Quotations V2 update Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-08-05 20:23 +0100
  Re: RFD: Quotations V2 update Bernd Paysan <bernd.paysan@gmx.de> - 2015-08-04 22:00 +0200
    Re: RFD: Quotations V2 update "Alex McDonald" <blog@rivadpm.com> - 2015-08-04 21:07 +0100
  Re: RFD: Quotations V2 update Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-08-04 21:53 +0100
    Re: RFD: Quotations V2 update "Alex McDonald" <blog@rivadpm.com> - 2015-08-04 23:22 +0100
      Re: RFD: Quotations V2 update Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-08-05 12:38 +0100
        Re: RFD: Quotations V2 update "Alex McDonald" <blog@rivadpm.com> - 2015-08-05 13:41 +0100
          Re: RFD: Quotations V2 update anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-08-05 12:46 +0000
            Re: RFD: Quotations V2 update Bernd Paysan <bernd.paysan@gmx.de> - 2015-08-06 02:12 +0200
              Re: RFD: Quotations V2 update "Alex McDonald" <blog@rivadpm.com> - 2015-08-06 14:16 +0100
              Re: RFD: Quotations V2 update anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-08-06 13:46 +0000
    Re: RFD: Quotations V2 update anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-08-05 08:15 +0000
      Re: RFD: Quotations V2 update Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-08-05 20:31 +0100
        Re: RFD: Quotations V2 update peter.m.falth@gmail.com - 2015-08-05 14:41 -0700
          Re: RFD: Quotations V2 update "Elizabeth D. Rather" <erather@forth.com> - 2015-08-05 18:39 -1000
            Re: RFD: Quotations V2 update peter.m.falth@gmail.com - 2015-08-05 23:22 -0700
        Re: RFD: Quotations V2 update anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-08-06 13:19 +0000
          Re: RFD: Quotations V2 update Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-08-07 22:28 +0100
            Re: RFD: Quotations V2 update Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-08-07 22:34 +0100
              Re: RFD: Quotations V2 update anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-08-08 15:53 +0000
                Re: RFD: Quotations V2 update Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-08-11 21:16 +0100
            Re: RFD: Quotations V2 update anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-08-08 15:39 +0000
              Re: RFD: Quotations V2 update Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-08-10 12:55 +0100
                Re: RFD: Quotations V2 update anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-08-10 12:08 +0000
  Re: RFD: Quotations V2 update hughaguilar96@gmail.com - 2015-08-04 18:09 -0700
    Re: RFD: Quotations V2 update "Alex McDonald" <blog@rivadpm.com> - 2015-08-05 09:22 +0100
    Re: RFD: Quotations V2 update "Alex McDonald" <blog@rivadpm.com> - 2015-08-05 09:53 +0100

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