\startcomponent ma-cb-en-commands

\enablemode[**en-us]

\project ma-cb

\startchapter[title=Defining commands / macros]

\CONTEXT\ is a set of macros based on \TEX. \TEX\ is a programming language as
well as a typographical system. This means that you can do the programming
yourself if you need that kind of flexability.

You can define a new command with:

\shortsetup{define}

The next example will explain its meaning.

You may have a well illustrated document and you are tired of typing:

\startbuffer
\placefigure
  [here,force]
  [fig:logical name]
  {Caption.}
  {\externalfigure[filename][width=5cm]}
\stopbuffer

\typebuffer

You could define your own command with a few variables like:

\startitemize[packed]
\item logical name
\item caption
\item file name
\stopitemize

Your command definition and call could look something like
this:

\startbuffer
\define[3]\myputfigure
  {\placefigure
     [here,force][fig:#1]
     {#2}{\externalfigure[#3][width=5cm]}}

\myputfigure{lion}{The Dutch lion is a sentry.}{ma-cb-13}
\stopbuffer

\typebuffer

From then on the \type{\myputfigure} is available.
Between brackets \type{[3]} indicates that you want to use three variables
\type{#1}, \type{#2} and \type{#3}. In the command call \type{\myputfigure} you
have to place these variables between curly braces. The result is shown in
\in{figure}[fig:lion].

\getbuffer

Very sophisticated commands can be programmed, but this is left to your own
inventiveness.

In addition to defining commands you can also define \type{\start...\stop}
command pairs.

\shortsetup{definestartstop}

For example:

\startbuffer
\definestartstop
   [attention]
   [before=\blank\startmarginrule,
    after=\stopmarginrule\blank]

\startattention
{\em Hasselter Juffers} are sweet cookies but the name is no
coincidence. On July 21 in 1233 the {\em Zwartewaterklooster}
(Blackwater Monastery) was founded. The monastery was meant
for unmarried girls and women belonging to the nobility of
Hasselt. These girls and women were called {\em juffers}.
\stopattention
\stopbuffer

\typebuffer

This will result in:

\getbuffer

\stopchapter

\stopcomponent