Re: [NTG-context] What do \start and \stop mean?

2013-09-30 Thread Aditya Mahajan 

On Mon, 30 Sep 2013, Lars Huttar wrote:


I found \start and \stop referenced in the context reference manual
(e.g. section 5.5).
While \startXYZ - \stopXYZ pairs are discussed earlier, I can't find any
place that \start and \stop (with no suffix) are described.
They seem to be used like \bgroup and \egroup. Is that right?
They are defined in core-sys.mkiv, but I can't figure out from there
what they actually do.


(Untested, based on what I remember):

\start = \bgroup
\stop  = \egroup

but \start scans the next argument, so there are situations when 
\start may fail but \bgroup works.


\start[whatever] ... \stop = \startwhatever ... \stopwhatever


Aditya
___
If your question is of interest to others as well, please add an entry to the 
Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
wiki : http://contextgarden.net
___

Re: [NTG-context] What do \start and \stop mean?

2013-09-30 Thread luigi scarso 
On Mon, Sep 30, 2013 at 5:38 PM, Lars Huttar lars_hut...@sil.org wrote:

 I found \start and \stop referenced in the context reference manual
 (e.g. section 5.5).
 While \startXYZ - \stopXYZ pairs are discussed earlier, I can't find any
 place that \start and \stop (with no suffix) are described.
 They seem to be used like \bgroup and \egroup. Is that right?
 They are defined in core-sys.mkiv, but I can't figure out from there
 what they actually do.

 I'll contribute documentation for them if someone can tell me what they
 mean.

 Thanks,
 Lars





core-sys.mkiv :


\unexpanded\def\start
  {\dosingleempty\syst_start}

\def\syst_start
  {\bgroup
   \iffirstargument
 \expandafter\syst_start_yes
   \else
 \expandafter\syst_start_nop
   \fi}

\def\syst_start_yes[#1]%
 {\edef\m_syst_start_stop{#1}%
  \ifx\m_syst_start_stop\empty
\let\syst_stop_indeed\donothing
  \else\ifcsname\e!start\m_syst_start_stop\endcsname

\expandafter\let\expandafter\syst_stop_indeed\csname\e!stop\m_syst_start_stop\endcsname

\csname\e!start\m_syst_start_stop\expandafter\expandafter\expandafter\endcsname
  \else
\let\syst_stop_indeed\donothing
  \fi\fi}

\def\syst_start_nop[#1]%
  {\let\syst_stop_indeed\donothing}

\unexpanded\def\stop
  {\syst_stop_indeed
   \egroup}


(it should be \let\donothing\empty)



-- 
luigi
___
If your question is of interest to others as well, please add an entry to the 
Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
wiki : http://contextgarden.net
___

Re: [NTG-context] What do \start and \stop mean?

2013-09-30 Thread luigi scarso 
On Mon, Sep 30, 2013 at 6:00 PM, luigi scarso luigi.sca...@gmail.comwrote:




 On Mon, Sep 30, 2013 at 5:38 PM, Lars Huttar lars_hut...@sil.org wrote:

 I found \start and \stop referenced in the context reference manual
 (e.g. section 5.5).
 While \startXYZ - \stopXYZ pairs are discussed earlier, I can't find any
 place that \start and \stop (with no suffix) are described.
 They seem to be used like \bgroup and \egroup. Is that right?
 They are defined in core-sys.mkiv, but I can't figure out from there
 what they actually do.

 I'll contribute documentation for them if someone can tell me what they
 mean.

 Thanks,
 Lars





 core-sys.mkiv :


 \unexpanded\def\start
   {\dosingleempty\syst_start}

 \def\syst_start
   {\bgroup
\iffirstargument
  \expandafter\syst_start_yes
\else
  \expandafter\syst_start_nop
\fi}

 \def\syst_start_yes[#1]%
  {\edef\m_syst_start_stop{#1}%
   \ifx\m_syst_start_stop\empty
 \let\syst_stop_indeed\donothing
   \else\ifcsname\e!start\m_syst_start_stop\endcsname

 \expandafter\let\expandafter\syst_stop_indeed\csname\e!stop\m_syst_start_stop\endcsname

 \csname\e!start\m_syst_start_stop\expandafter\expandafter\expandafter\endcsname
   \else
 \let\syst_stop_indeed\donothing
   \fi\fi}

 \def\syst_start_nop[#1]%
   {\let\syst_stop_indeed\donothing}

 \unexpanded\def\stop
   {\syst_stop_indeed
\egroup}


 (it should be \let\donothing\empty)

 sorry, hit return too early.
\start ... \stop without argument is

\bgroup % from\def\syst_start
\expandafter\syst_start_nop

\syst_start_nop is
{\let\syst_stop_indeed\donothing}

and \stop is hence
\syst_stop_indeed
\egroup
i.e.
\donothing
\egroup


are like \bgroup ... \egroup

It seems that there are no examples of \start[]..\stop .

-- 
luigi
___
If your question is of interest to others as well, please add an entry to the 
Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
wiki : http://contextgarden.net
___