use Perl

Did you mean to say

if (
    eval {
        my $obj = SomeClass->new();
        die "Code Red!\n";
        1;
    }
) {
    print "No exception occurred\n";
} else {
    print "Exception caught: $@\n";
}

I apologize for this trouble.

Here it is again:

http://www.fullsail.edu/index.cfm?fa=landing.WDD_4a&mnc=779&kw=cont-java%20scrip t%20training&utm_source=google&utm_medium=cpc&utm_term=java%20script%20training& utm_content=WDD_4a&utm_campaign=WDD

Following the eval block with an "or" seems to be more reliable than using "if ($@)" to check for an exception in an eval block, because an eval block (or even an eval EXPR) returns undef if there is a syntax error or runtime error or a die statement is executed (according to perldoc -f eval).


        eval {
                my $obj = SomeClass->new();
                die "Code Red!\n";
        } or print "Exception caught: $@\n";


But even with this technique the $@ is reset by the destructor in your example, so while the exception at least can be caught we lose the information $@ would provide but for the destructor. The output is merely

"Exception caught:"


The documentation for eval says that $@ is guaranteed to be a null string if no exception occurred; I had not appreciated the precise scope of that statement until seeing your example (it doesn't go on to say that, conversely, $@ is guaranteed not to be a null string if an exception occurred).

I believe I heard schwern advocating at YAPC 2008 the use of

eval { ... }
        or warn_about_problem();

rather than

eval { ... };
if ($@) { warn_about_problem() }

This might have been the kind of situation he had in mind.