Evaluate success or failure of a subroutine

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

Hi Monks,
I would like to know, how could I evaluate the status of a subroutine. See the subroutine below. If it fails, I would like to capture the status and process something else. All your help is appreciated.

sub verifyRecCount ($,$,$)
{
    my ($recCount)         = @_[0];
    my ($tlrRecordCount)     = @_[1];
    my ($verRecordCount)     = @_[2];

    if ($recCount == $tlrRecordCount) {
            slog($logfile,"Comparing Record Count: $recCount to $tlrRe
+cordCount. (OK!)");
            $verRecordCount = 1;
    } else {
            slog($logfile,"Comparing Record Count: $recCount to $tlrRe
+cordCount. (FAILED!)");
            exit 6;
    }
    return $verRecordCount;
}# verifyRecCount()
[download]

Thanks

20040816 Janitored by Corion: Fixed code tag, added formatting

Comment on Evaluate success or failure of a subroutine Download Code

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Re: Evaluate success or failure of a subroutine by japhy (Canon) on Aug 16, 2004 at 13:46 UTC
Don't use `exit()` to leave a subroutine, it stops your program entirely. Instead, return a specific value, like 0, and set some global error variable if you want. _____________________________________________________ Jeff `japhy` Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and `perl` hacker How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart	[reply] [d/l]
Re: Evaluate success or failure of a subroutine by Zaxo (Archbishop) on Aug 16, 2004 at 13:49 UTC
If you change exit 6; to die 6, you can call your sub with `my $result = eval { verifyRecCount($foo, $bar, $baz) }; doSomethingElse() if $@;` [download] That is perl's version of exception handling for errors. The other model is to return undef on error. Then defined can be used on the result to test for success. After Compline, Zaxo	[reply] [d/l]
Re: Evaluate success or failure of a subroutine by Joost (Canon) on Aug 16, 2004 at 13:49 UTC
You can't stop an `exit`, but you can catch the return code using `my $ret = system("$0 arguments")` or something like it. The usual approach is to use die() instead: `sub some_sub { die "Error" if ($some_condition); } eval { my $value = some_sub(); # do stuff with $value }; if (my $exception = $@) { # exception! handle error here }` [download] "What should it profit a man, if he should win a flame war, yet lose his cool?"	[reply] [d/l] [select]
Re: Evaluate success or failure of a subroutine by naChoZ (Curate) on Aug 16, 2004 at 15:19 UTC
You've already received good responses, but I just thought I'd mention: `my ($recCount) = @_[0]; my ($tlrRecordCount) = @_[1]; my ($verRecordCount) = @_[2];` [download] ...can be expressed: `my ( $recCount, $tlrRecordCount, $verRecordCount ) = @_;` [download] -- "A long habit of not thinking a thing wrong, gives it a superficial appearance of being right." -- Thomas Paine naChoZ	[reply] [d/l] [select]
Re^2: Evaluate success or failure of a subroutine by ikegami (Patriarch) on Aug 16, 2004 at 15:51 UTC
wusphere, while I prefer naChoZ's style, if you like the multi-line style, consider using `my $recCount = $_[0]; my $tlrRecordCount = $_[1]; my $verRecordCount = $_[2];` [download] since it is much more efficient then taking array slices: `my ($recCount) = @_[0]; my ($tlrRecordCount) = @_[1]; my ($verRecordCount) = @_[2];` [download] `$array[num]` means "get element num from the array @array". `@array[num]` means "create an array consiting of the element num of the array @array".	[reply] [d/l] [select]