mkiv: append to buffer

mkiv: append to buffer

[Thomas Schmitz]

Hi all,

i guess this is easy, but I can't find an example to help
me: I want to write a macro that will collect one of its
arguments in a buffer and then collect the other argument 
in a buffer. Difficult to make a minimal example since I 
don't know how to do this, so here is some pseudo-code; 
this is what I want to achieve:

\definebuffer[MyBuffer]

\def\MyGreatMacro#1#2#3%
{\item[#1] #2 \par
  \appendtobuffer{MyBuffer}{\in[#1] #3}}

\starttext
\startitemize
\MyGreatMacro{1}{aa}{AA}
\MyGreatMacro{2}{bb}{BB}
\stopitemize

\page
\getbuffer[MyBuffer]
\resetbuffer[MyBuffer] % so I can reuse the buffer
\stoptext

What I want to do with this is typeset exercises for my 
students, with an itemization for problems and solutions 
which use the same numbering. In real life, this will 
involve xml, but I will try and figure that out myself 
once I know how to use buffers...

It looks like buffers.collectcontent should be able to do 
this, but I can't figure out how to use it. Any pointers? 
Thanks a lot!

All best

Thomas
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Re: mkiv: append to buffer

[Aditya Mahajan]

On Sat, 18 Dec 2010, Thomas Schmitz wrote:

> i guess this is easy, but I can't find an example to help
> me: I want to write a macro that will collect one of its
> arguments in a buffer and then collect the other argument in a buffer. 
> Difficult to make a minimal example since I don't know how to do this, so 
> here is some pseudo-code; this is what I want to achieve:
>
> \definebuffer[MyBuffer]
>
> \def\MyGreatMacro#1#2#3%
> {\item[#1] #2 \par
> \appendtobuffer{MyBuffer}{\in[#1] #3}}
>
> \starttext
> \startitemize
> \MyGreatMacro{1}{aa}{AA}
> \MyGreatMacro{2}{bb}{BB}
> \stopitemize
>
> \page
> \getbuffer[MyBuffer]
> \resetbuffer[MyBuffer] % so I can reuse the buffer
> \stoptext
>
> What I want to do with this is typeset exercises for my students, with an 
> itemization for problems and solutions which use the same numbering. In real 
> life, this will involve xml, but I will try and figure that out myself once I 
> know how to use buffers...
>
> It looks like buffers.collectcontent should be able to do this, but I can't 
> figure out how to use it. Any pointers? Thanks a lot!

I am not sure what you want to do, and why you want to use buffers. Wont a 
simple token list work?

% Define a token list
\newtoks\mytoks

% Append to a token list
\appendtoks \in[#1] #3  \to\mytoks

% Recall a token list
\the\mytoks

% Reset a token list
\mytoks\emptytoks

For repeating question and answers, there is also blocks.

Aditya

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Re: mkiv: append to buffer

[Wolfgang Schuster]

Am 18.12.2010 um 17:52 schrieb Aditya Mahajan:

> I am not sure what you want to do, and why you want to use buffers. Wont a simple token list work?

I can only agree with this, token lists are the easiest solution but the new cld manuals mentions the “context.tobuffer” function which allows one to add content to a buffer.

Wolfgang

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Re: mkiv: append to buffer

[Thomas Schmitz]

On Sat, 18 Dec 2010 19:35:53 +0100
  Wolfgang Schuster <schuster.wolfgang@googlemail.com> 
wrote:
> 
> Am 18.12.2010 um 17:52 schrieb Aditya Mahajan:
> 
>> I am not sure what you want to do, and why you want to 
>>use buffers. Wont a simple token list work?
> 
> I can only agree with this, token lists are the easiest 
>solution but the new cld manuals mentions the 
>“context.tobuffer” function which allows one to add 
>content to a buffer.
> 
> Wolfgang

Aditya, Wolfgang, thanks for your replies. I didn't want 
to bore the list with lengthy explanations, but maybe I 
didn't give enough information. So here comes what I hope 
are the relevant bits: I'm typesetting sheets with 
problems and solutions for a class. Those come from an xml 
database. Unfortunately, there is one catch: depending on 
the type of the problem, some problems don't have an 
explicit solution. The problems are typeset as a numbered 
itemization on page 1; on page 2, I want the solutions, 
with matching numbers. And since I'm lazy, I don't want to 
take care of this myself but have context do it for me. So 
let's begin with the output. I want:

PROBLEMS

1. problem without solution

2. problem with solution

3. problem without solution

4. problem with solution

and then, on a new page:

SOLUTIONS

2. solution to 2

4. solution to 4

So: I have been trying to write a macro that will retrieve 
problems from the database (successful, with help by 
Hans), pack them in an itemize list (successful), and 
store the solution somewhere so it can be typeset on the 
next page (unsuccessful as yet). I thought buffers were 
the natural way to go, but I must admit I didn't know 
about tokenlists. Aditya's suggestion unfortunately 
doesn't seem to work with itemizations. Test files:

This works:

\newtoks\mytoks

\def\TestMacro#1#2#3%
   {\color[darkred]{#1} \color[darkblue]{#2}\endgraf
    \appendtoks \color[darkgreen]{#3} \to\mytoks}

\starttext

\TestMacro{A}{B}{C}

\TestMacro{X}{Y}{Z}

\hairline

\the\mytoks

and this doesn't:

\newtoks\mytoks

\def\TestMacro#1#2#3%
   {\item[#1] #2\par
    \appendtoks \in[#1]: {#3} \to\mytoks}

\starttext

\startitemize[n]

\TestMacro{A}{B}{C}

\TestMacro{X}{Y}{Z}
\stopitemize

\hairline

\the\mytoks

I have absolutely no preference for buffers or 
itemizations or whatever, so if there's a better solution, 
I'm all open. But for the time being, I don't get what I 
want. I'll look into "context.tobuffer" next...

Thanks for any suggestions, and best wishes

Thomas
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Re: mkiv: append to buffer

[Peter Münster]

On Sun, Dec 19 2010, Thomas Schmitz wrote:

> and this doesn't:
> 
> \newtoks\mytoks
> 
> \def\TestMacro#1#2#3%
>   {\item[#1] #2\par
>    \appendtoks \in[#1]: {#3} \to\mytoks}


     \doglobal \appendtoks \in[#1]: {#3} \to\mytoks}

Cheers, Peter

-- 
Contact information: http://pmrb.free.fr/contact/
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Re: mkiv: append to buffer

[Thomas Schmitz]

On Sun, 19 Dec 2010 13:21:26 +0100
  Peter Münster <pmlists@free.fr> wrote:
> On Sun, Dec 19 2010, Thomas Schmitz wrote:
> 
>> and this doesn't:
>> 
>> \newtoks\mytoks
>> 
>> \def\TestMacro#1#2#3%
>>   {\item[#1] #2\par
>>    \appendtoks \in[#1]: {#3} \to\mytoks}
> 
> 
>     \doglobal \appendtoks \in[#1]: {#3} \to\mytoks}
> 
> Cheers, Peter

Hooray, not it works!!! Thanks a lot, everyone, thanks 
Peter - so easy, yet my knowledge of TeX wasn't advanced 
enough to see this. Is it because I'm inside a group and 
TeX empties the tokenlist once I get out of the group?

All best

Thomas
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Re: mkiv: append to buffer

[Thomas Schmitz]

> 
> Hooray, not it works!!! 

s/not/now/

Thomas
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Re: mkiv: append to buffer

[Hans Hagen]

On 19-12-2010 12:28, Thomas Schmitz wrote:

> So: I have been trying to write a macro that will retrieve problems from
> the database (successful, with help by Hans), pack them in an itemize
> list (successful), and store the solution somewhere so it can be typeset

Why do you store the solutions if they're already stored in the xml? You 
can just filter them any time you want, can't you?

Hans

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Re: mkiv: append to buffer

[Peter Münster]

On Sun, Dec 19 2010, Thomas Schmitz wrote:

> easy, yet my knowledge of TeX wasn't advanced enough to see this. Is
> it because I'm inside a group and TeX empties the tokenlist once I
> get out of the group?

In this case yes, because the list was empty before the group. In general
you get the value, that you had before entering the group.
Peter

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