<HEAD> <TITLE> catch - catch an evaluation error </TITLE> </HEAD> <BODY BACKGROUND=http://www.imaginary.com/~beek/gifs/bg.jpg TEXT=#000000 ALINK=#FFFF00 VLINK=#550000 LINK=#000099> <center> <H1> catch - catch an evaluation error </H1> </center>
<p>
<b> mixed catch( mixed expr ); </b>
<p>
<b> mixed catch { ... }; </b>
<p>
Note: catch is really a keyword and not an efun.
<p>
The code inside the { ... } or the expression is evaluated. If there
is no error, catch() returns zero. If there is an error, a string (with
a leading '*') will be returned.
<p>
The function throw() can also be used to immediately return any value,
except 0.
<p>
The catch() is somewhat costly, and should not be used just anywhere.
Rather, use it at places where an error would destroy consistency.
<p>
See also:
<A HREF=../system/error.html> error </A>,
<A HREF=throw.html> throw </A>,
<A HREF=../../applies/master/error_handler.html> error_handler </A>
<p>
<HR> <ADDRESS> <A HREF=http://wagner.princeton.edu/~tim> Tim Hollebeek </A> <p> <A HREF="http://www.imaginary.com/~beek/"> Beek </A>@ZorkMUD, Lima Bean, IdeaExchange, TMI-2, and elsewhere </ADDRESS>