Difference between revisions of "Inside ConTeXt"

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(Processing a comma-separated list of values)
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>
 
>
  
== Processing a comma-separated list of values ==
+
== Processing lists of values ==
 +
=== Processing a comma-separated list of values ===
  
 
Suppose you defined a command like this one somewhere in your document:
 
Suppose you defined a command like this one somewhere in your document:
Line 65: Line 66:
 
\def\MyMumOrderedMeTo[#1]#2%
 
\def\MyMumOrderedMeTo[#1]#2%
 
   {\begingroup
 
   {\begingroup
   \def\processitem##1{\IHaveToDo[##1]{#2}}%
+
   \def\processitem##1{\IHaveTo[##1]{#2}}%
 
   \processcommalist[#1]\processitem
 
   \processcommalist[#1]\processitem
 
   \endgroup}
 
   \endgroup}
 
</texcode>
 
</texcode>
 +
 +
=== Processing a dash-separated list of values ===
 +
 +
Sometimes you have more work to do than just that borring stuff at home. And as it is quite important as well, you don't want to loose your time enumerating all of the tasks. Being able to do something like
 +
<texcode>
 +
\IHaveToDoTheTasks[1-4,7,9-11]{until tomorrow}
 +
</texcode>
 +
may sound like a good idea.
 +
 +
Suppose you already defined:
 +
<texcode>
 +
\def\IHaveToDoTheTask[#1]#2{The task #1 has to be done #2.\par}
 +
</texcode>
 +
 +
You have to define some macros first (thanks to Taco!):
 +
<texcode>
 +
% a few auxiliary core macros are needed to uncompress the list.
 +
%
 +
% \uncompresslist is the twin of the already existing \compresslist
 +
% which works in the other direction (syst-new)
 +
%
 +
\unprotect
 +
 +
% I guess this function is already available but couldnt find it...
 +
%
 +
\def\apptomac#1#2%
 +
  {\ifx#1\empty\def#1{#2}\else \@EA\def\@EA#1\@EA{#1,#2}\fi}
 +
 +
% the next macro does this:
 +
%
 +
% \itemwithdash<<9-11>>- => \dorecurse {<<1+11-9>>}
 +
%    {\apptomac\uncompressedlist<<9-1+\recurselevel>>}
 +
%
 +
% (the 1+ and -1 are needed to solve a counter offset.)
 +
\def\itemwithdash#1-#2-%
 +
  {\@EA\dorecurse\@EA
 +
    {\the\numexpr 1+#2-#1\relax}%
 +
    {\@EA\apptomac\@EA\uncompressedlist\@EA
 +
      {\the\numexpr #1-1+\recurselevel\relax}}}%
 +
 +
% top level. The result will be in \uncompressedlist
 +
\def\uncompresslist[#1]%
 +
  {\def\uncompressedlist{}%
 +
  \def\processitem##1%
 +
    {\doifinstringelse{-}{##1}
 +
      {\itemwithdash##1-}
 +
      {\apptomac\uncompressedlist{##1}}}%
 +
  \processcommalist[#1]\processitem }
 +
 +
\protect
 +
</texcode>
 +
 +
And then you're ready to define
 +
<texcode>
 +
\def\IHaveToDoTheTasks[#1]#2%
 +
  {\begingroup
 +
  \uncompresslist[#1]% <= Yeah!
 +
  \def\processitem##1{\IHaveToDoTheTask[##1]{#2}}%
 +
  \processcommacommand[\uncompressedlist]\processitem
 +
  \endgroup}
 +
</texcode>
 +
 +
Guess what! Your <tt>\IHaveToDoTheTasks[1-4,7,9-11]{until tomorrow}</tt> resulted in:
 +
The task 1 has to be done until tomorrow.
 +
The task 2 has to be done until tomorrow.
 +
The task 3 has to be done until tomorrow.
 +
The task 4 has to be done until tomorrow.
 +
The task 7 has to be done until tomorrow.
 +
The task 9 has to be done until tomorrow.
 +
The task 10 has to be done until tomorrow.
 +
The task 11 has to be done until tomorrow.
 +
 +
So - what are you still waiting for? Go back to work and do them right away!

Revision as of 20:46, 4 July 2005

< Main Page

Using variables

\setvariables[namespace][key=value]
\getvariable{namespace}{key}

Defining new commands

Special characters in command names

Some commands have special characters in their names, that TeX normally does not consider to be letters: @, ! and ?. Before and after the use or definition of such protected commands in your input files, the catcode of these characters has to be changed. This is done by \unprotect and \protect:

\unprotect
\def\!test{alfa} 
\protect 

The newly defined command \!test can of course only be called upon when we are in the \unprotected state, otherwise TeX reads the command \!, followed by the word test (and probably complains loudly about not being in math mode). These protection/unprotection commands can be nested. When the nesting becomes deeper than one level, the system reports the current protection level. It is a good habit to always start your macro files with \unprotect and end them with \protect.

See also: Commands with Key=Value arguments, Commands with optional arguments >

Processing lists of values

Processing a comma-separated list of values

Suppose you defined a command like this one somewhere in your document:

\def\IHaveTo#1#2{I have to #1 on #2.\par}

So calling

\IHaveTo{tidy up}{Monday}

Will print out

I have to tidy up on Monday.

But sometimes you have to repeat some task more than once. In this case you can define a new command:

\def\MyMumOrderedMeTo[#1]#2%
  {\processcommalist[#1]{\IHaveTo{#2}}}

Calling

\MyMumOrderedMeTo[Monday,Wednesday,Saturday]{tidy up}

will spare you some typing (however not tidying up!):

I have to tidy up on Monday.
I have to tidy up on Wednesday.
I have to tidy up on Saturday.

In case a command \IHaveTo is already defined in a slightly different way:

\def\IHaveTo[#1]#2{I have to #2 on #1.\par}

you can define \MyMumOrderedMeTo as:

\def\MyMumOrderedMeTo[#1]#2%
  {\begingroup
   \def\processitem##1{\IHaveTo[##1]{#2}}%
   \processcommalist[#1]\processitem
   \endgroup}

Processing a dash-separated list of values

Sometimes you have more work to do than just that borring stuff at home. And as it is quite important as well, you don't want to loose your time enumerating all of the tasks. Being able to do something like

\IHaveToDoTheTasks[1-4,7,9-11]{until tomorrow}

may sound like a good idea.

Suppose you already defined:

\def\IHaveToDoTheTask[#1]#2{The task #1 has to be done #2.\par}

You have to define some macros first (thanks to Taco!):

% a few auxiliary core macros are needed to uncompress the list.
%
% \uncompresslist is the twin of the already existing \compresslist
% which works in the other direction (syst-new)
%
\unprotect

% I guess this function is already available but couldnt find it...
%
\def\apptomac#1#2%
  {\ifx#1\empty\def#1{#2}\else \@EA\def\@EA#1\@EA{#1,#2}\fi}

% the next macro does this:
%
% \itemwithdash<<9-11>>- => \dorecurse {<<1+11-9>>}
%     {\apptomac\uncompressedlist<<9-1+\recurselevel>>}
%
% (the 1+ and -1 are needed to solve a counter offset.)
\def\itemwithdash#1-#2-%
  {\@EA\dorecurse\@EA
    {\the\numexpr 1+#2-#1\relax}%
    {\@EA\apptomac\@EA\uncompressedlist\@EA
      {\the\numexpr #1-1+\recurselevel\relax}}}%

% top level. The result will be in \uncompressedlist
\def\uncompresslist[#1]%
  {\def\uncompressedlist{}%
   \def\processitem##1%
     {\doifinstringelse{-}{##1}
       {\itemwithdash##1-}
       {\apptomac\uncompressedlist{##1}}}%
   \processcommalist[#1]\processitem }

\protect

And then you're ready to define

\def\IHaveToDoTheTasks[#1]#2%
  {\begingroup
   \uncompresslist[#1]% <= Yeah!
   \def\processitem##1{\IHaveToDoTheTask[##1]{#2}}%
   \processcommacommand[\uncompressedlist]\processitem
   \endgroup}

Guess what! Your \IHaveToDoTheTasks[1-4,7,9-11]{until tomorrow} resulted in:

The task 1 has to be done until tomorrow.
The task 2 has to be done until tomorrow.
The task 3 has to be done until tomorrow.
The task 4 has to be done until tomorrow.
The task 7 has to be done until tomorrow.
The task 9 has to be done until tomorrow.
The task 10 has to be done until tomorrow.
The task 11 has to be done until tomorrow.

So - what are you still waiting for? Go back to work and do them right away!