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%W  example.tex            GAP documentation                Werner Nickel
%W                                                            Greg Gamble
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%H  $Id: example.tex,v 4.5 2006/01/31 11:18:12 gap Exp $
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%Y  Copyright (C) 1997, School of Math & Comp. Sci., St Andrews, Scotland
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\Chapter{The Example Package}

\atindex{Example package}{@Example package}
This chapter  describes  the  {\GAP}  package  {\Example}.  As  its  name
suggests it is an example of how to  create  a  {\GAP}  package.  It  has
little functionality except for being a package.

See Sections~"Installing the Example Package"  and~"Loading  the  Example
Package"  for  how  to  install  and  load  the  {\Example}  package,  or
Appendix~"Hints for writing a GAP Package" for hints on how  to  write  a
{\GAP} package.

If you are viewing this with on-line help, type: 

\beginexample
gap> ?>
\endexample

to see the functions provided by the {\Example} package.

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\Section{The main functions}

The following functions are available:

\>ListDirectory([<dir>]) F

lists the files in directory <dir> (a string) or the current directory if
called with no arguments.

\>FindFile( <directory_name>, <file_name> ) F

searches  for the  file   <file_name> in  the  directory  tree  rooted at
<directory_name> and returns the absolute path names of  all  occurrences
of this file as a list of strings.

\>LoadedPackages() F

returns a list with the names of the packages that have  been  loaded  so
far. All this does is execute

\beginexample
gap> RecNames( GAPInfo.PackagesLoaded );
\endexample

You might like to check out some of the other information in the `GAPInfo'
record.

\>Which( <prg> ) F

returns the path of the program executed if `Exec(<prg>);' is called, e.g.

\beginexample|unstableoutput
gap> Which("date");         
"/bin/date"
gap> Exec("date");
Sun Oct  7 16:23:45 CEST 2001
\endexample

\>WhereIsPkgProgram( <prg> ) F

returns a list of paths of  programs  with  name  <prg>  in  the  current
packages loaded. Try:

\beginexample
gap> WhereIsPkgProgram( "hello" );
\endexample

\>HelloWorld() F

executes the C program `hello' provided by the {\Example} package.

\>`FruitCake' V

is a record with the bits and pieces needed to make a boiled fruit  cake.
Its fields satisfy the criteria for `Recipe' (see~"Recipe");

\>Recipe( <cake> ) M

displays the recipe for cooking <cake>, where <cake>  is  a  record.  The
fields of <cake> recognised are `name' (a string giving the type of  cake
or  cooked  item),  `ovenTemp'  (a  string),  `cookingTime'  (a  string),
`ingredients' (a list of strings each containing an `_' which is used  to
line up the entries and is replaced by a  blank),  `method'  (a  list  of
steps, each of which is a string or list of strings), and `notes' (a list
of strings).

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