function or something

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

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Re: function or something by philcrow (Priest) on Jul 20, 2006 at 15:35 UTC
If something is dying, try wrapping it in an eval {}; block. After the block any error will be in $@. Phil	[reply]
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Re: function or something by bobf (Monsignor) on Jul 20, 2006 at 15:43 UTC
If I understand you correctly, you want to set $!. From the docs (emphasis mine): If used numerically, ($!) yields the current value of the C errno variable, with all the usual caveats. (This means that you shouldn't depend on the value of $! to be anything in particular unless you've gotten a specific error return indicating a system error.) If used an a string, yields the corresponding system error string. You can assign a number to $! to set errno if, for instance, you want "$!" to return the string for error n, or you want to set the exit value for the die() operator. Update: Now that I reread the question, I can't tell if you're trying to return an exit value from a program (as I initially thought) or simply trap a fatal error within the same program. Please elaborate if I misunderstood.	[reply]
Re: function or something by ysth (Canon) on Jul 20, 2006 at 16:25 UTC
This, however, doesn't work. An error is still printed to stdout and the program colapses on itself. "An error"? What error? Providing details like that can really help others help you. Also, I suspect the error went to stderr, not stdout.	[reply]
Re: function or something by imp (Priest) on Jul 20, 2006 at 16:47 UTC
One thing to keep in mind if you use eval {} is that a return inside the eval block returns from that block - not from the outer function. `sub example { my $number = shift; eval { if (2 / $number > 3) { return 1; } }; print "Still here\n"; }` [download] To capture the value returned, you can do this: `my $value = eval { # Do stuff; return 4; };` [download] Alternately: `my $value; eval { # Do stuff; $value = 4; };` [download]	[reply] [d/l] [select]
Re: function or something by mrbbking (Hermit) on Jul 20, 2006 at 16:03 UTC
I'm not sure if you want your program to return a value, or you want the subroutine to return a value. If the program, do `someFunction() or exit(1);` [download] If the function, you'll have to catch the value the sub returns and do your thing with it. `my $ret = someFunction(); if( $ret ){ do_your_thing(); maybe_return_here(); }` [download] /me needs a new .sig	[reply] [d/l] [select]
Re: function or something by shmem (Chancellor) on Jul 20, 2006 at 16:50 UTC
Depending on what modules you are using in your program, you might want to set up signal handlers `{ local $SIG{__DIE__}; local $SIG{__WARN__}; $ret = eval { someFunction() }; warn $@ if $@; }` [download] to mask some other modules handlers, which might choose to just `exit($!)` or tread on `$@` or `$!`. --shmem _($_=" "x(1<<5)."?\n".q·/)Oo. G°\ / /\_¯/(q / ---------------------------- \__(m.====·.(_("always off the crowd"))."· ");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}	[reply] [d/l] [select]
Re: function or something by sgifford (Prior) on Jul 21, 2006 at 03:02 UTC
The syntax you describe seems to work fine for me. This example works, at least: `my $ret = test(); print "Test returned $ret\n"; sub test { unlink("t64.test") or return 0; print "Test completed.\n"; return 1; }` [download] Maybe you need to look elsewhere for your problem? -- sgifford's Web page	[reply] [d/l]