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RAAB / SGMLSpm-1.1 / DOC / HTML / sgmlspl / specs.html 
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<TITLE>How does the specification file tell sgmlspl what to do?</TITLE>
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<H1>How does the specification file tell <A HREF=sgmlspl.html><TT>sgmlspl</TT></A> what to do?</H1>

<P><A HREF=sgmlspl.html><TT>sgmlspl</TT></A> uses an <I>event model</I> rather than
a <I>procedural model</I> -- instead of
saying "do A then B then C" you say "whenever X
happens, do A; whenever Y happens, do B; whenever Z happens, do
C".  In other words, while you design the code, <A HREF=sgmlspl.html><TT>sgmlspl</TT></A>
decides when and how often to run it.</P>

<P>The specification file, which contains your instructions, is
regular <A HREF="http://www.metronet.com/0/perlinfo/perl5/manual/perl.html"><TT>perl5</TT></A> code, and you can define packages and subroutines,
display information, read files, create variables, etc.  For
processing the <A HREF="http://www.sil.org/sgml/sgml.html"><B>SGML</B></A> document, however, <A HREF=sgmlspl.html><TT>sgmlspl</TT></A> exports a single
subroutine, <TT>sgml(<IT>event</IT>,
<IT>handler</IT>)</TT>, into the 'main' package
-- each time you call <TT>sgml</TT>, you declare a
handler for a specific type of <TT>sgmls</TT> <A HREF="../SGMLSpm/events.html">event</A>, and <A HREF=sgmlspl.html><TT>sgmlspl</TT></A> will then
execute that handler every time the event occurs.  You may use
<TT>sgml</TT> to declare a <A HREF=handlers.html>handler</A> for a <A HREF=generic.html><I>generic event</I></A>, like
<TT>'start_element'</TT>, or a <A HREF=specific.html><I>specific event</I></A>,
like <TT>'&lt;DOC&gt;'</TT> -- a specific event will
always take precedence over a generic event, so when the
<TT>DOC</TT> element begins, <A HREF=sgmlspl.html><TT>sgmlspl</TT></A> will execute the
<TT>'&lt;DOC&gt;'</TT> handler rather than the
<TT>'start_element'</TT> handler.</P>


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<ADDRESS>David Megginson <A HREF="mailto:dmeggins@aix1.uottawa.ca">&lt;dmeggins@aix1.uottawa.ca&gt;</A></ADDRESS>
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