Re^2: Executing Systems Calls with Care

[K_M_McMahon]

UPDATE: I modified this post because I thought noone had answered it and I thought better of my question after testing. In the interest of keeping following posts On Topic, this sub_question was initially,
"Will it work if you substitute &some_subroutine; instead of die?" in the section local $SIG{ALRM} = sub { die "alarm\n" };
CURRENT QUESTION:

     local $SIG{ALRM} = sub { die "alarm\n" };

I can replace the die "alarm\n" section here with a subroutine with no problems (actually tested it ;->)

but this brings up something else that I don't understand.. What causes the above example to enter the

if ($@) 
    {
    die unless $@ eq "alarm\n";   # propagate unexpected errors
    # handle the timed out operation
    }

section?

[matija]

Will it work if you substitute &some_subroutine; instead of die?

Well, in principle, sure. But make sure that he some_subroutine realizes that there may be error conditions it can't handle, and dies if it encounters a situation it isn't explicitly designed to handle.

You need to be defensive when you're designing this subroutine. Defensive and paranoid.

[phaylon]

As 'perldoc -f eval' says:

If the code to be executed doesn't vary, you may use the eval-BLOCK form to trap run-time errors without incurring the penalty of recompiling each time. The error, if any, is still returned in $@.