====== Mathematica ======
===== Error Handling =====

You may want to react on error messages created by a called function. For instance if you open a file and it cannot be opened.

<code>
Check[expr,failexpr]
</code>
evaluates expr, and returns the result, unless messages were generated, in which case it evaluates and returns failexpr.

<code>
Check[expr,failexpr,{s1::t1,s2::t2,…}]
</code>
checks only for the specified messages.

<code>
Check[expr,failexpr,"name"]
</code>
checks only for messages in the named message group.
 
Example:

<code>
Check[(a=<<"hallo"); , Print["could not open file"]; Exit[42]; , {Get::noopen}]
</code>