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<TITLE>LambdaMOO Programmer's Manual - Statement Errors</TITLE>
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<H3><A NAME="SEC29" HREF="ProgrammersManual_toc.html#TOC29">Errors While Executing Statements</A></H3>

<P>
Statements do not return values, but some kinds of statements can, under
certain circumstances described below, generate errors.  If such an error is
generated in a verb whose <SAMP>`d'</SAMP> (debug) bit is not set, then the error is
ignored and the statement that generated it is simply skipped; execution
proceeds with the next statement.

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<BLOCKQUOTE>
<P>
<STRONG>Note:</STRONG> this error-ignoring behavior is very error prone, since it
affects <EM>all</EM> errors, including ones the programmer may not have
anticipated.  The <SAMP>`d'</SAMP> bit exists only for historical reasons; it was once
the only way for MOO programmers to catch and handle errors.  The
error-catching expression and the <CODE>try</CODE>-<CODE>except</CODE> statement are far
better ways of accomplishing the same thing.
</BLOCKQUOTE>

<P>
If the <SAMP>`d'</SAMP> bit is set, as it usually is, then the error is <STRONG>raised</STRONG>
and can be caught and handled either by code surrounding the expression in
question or by verbs higher up on the chain of calls leading to the current
verb.  If the error is not caught, then the server aborts the entire task and,
by default, prints a message to the current player.  See the descriptions of
the error-catching expression and the <CODE>try</CODE>-<CODE>except</CODE> statement for
the details of how errors can be caught, and the chapter on server assumptions
about the database for details on the handling of uncaught errors.

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