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

I guys, I have a question about perl's defined loop.I have written a following code:

sub not_exposed_reason
{
    my ($self, $not_exposed_reason) = @_;
    $self->{_not_exposed_reason} = $not_exposed_reason if defined($not
+_exposed_reason);
    return $self->{_not_exposed_reason};
}

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When there is no exposed reason I wants to return "No exposed reason" string. My question how to return it?

Kindly let me know...Thanks in advance !!!!

Replies are listed 'Best First'.
Re: Question about defined loop
by ssandv (Hermit) on Mar 11, 2010 at 17:13 UTC

    defined is not a loop, it is a function. That may sound pedantic, but it's difficult to help people who use words wrong, because it's hard to understand them.

    One of many ways to do what (I *think*) you want would be to make the last line 
    return defined($not_exposed_reason)?$self->{_not_exposed_reason}:"No e
+xposed reason";

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    which uses the ? : construct (sometimes called the ternary conditional operator) to produce the value before the : if the condition before the ? is true, and the one after the : if the condition is false. I'm not entirely sure how helpful that is, because your question is pretty hard to parse.

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      Thanks a lot dude!!!!!Thats helped out .....
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      A reply falls below the community's threshold of quality. You may see it by logging in.
Re: Question about defined loop
by ikegami (Patriarch) on Mar 11, 2010 at 17:28 UTC
    Depending on when you want to set $self->{_not_exposed_reason}, 
    sub not_exposed_reason {
    my ($self, $not_exposed_reason) = @_;
    return
        $self->{_not_exposed_reason} = defined($not_exposed_reason)
            ? $not_exposed_reason
            : "No exposed reason";
}

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    or 
    sub not_exposed_reason {
    my ($self, $not_exposed_reason) = @_;
    if (defined($not_exposed_reason)) {
        return $self->{_not_exposed_reason} = $not_exposed_reason;
    } else {        
        return "No exposed reason";
    }
}

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    Note that 

    defined(X) ? X : Y

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    can be written as 
    X // Y

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    since Perl 5.10.
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Re: Question about defined loop
by JavaFan (Canon) on Mar 11, 2010 at 17:10 UTC
    I'm not quite sure I understand your question. Perhaps you want: 
    sub not_exposed_reason {
    my ($self, $not_exposed_reason) = @_;
    $self->{_not_exposed_reason} = $not_exposed_reason // "No exposed 
+reason";
}

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    On older Perls, you may want to write that as: 
    sub not_exposed_reason {
    my ($self, $not_exposed_reason) = @_;
    $self->{_not_exposed_reason} = defined $not_exposed_reason ? $not_
+exposed_reason : "No exposed reason";
}

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Re: Question about defined loop
by mje (Curate) on Mar 11, 2010 at 17:04 UTC 
    return defined($not_exposed_reason) || 'No exposed reason';

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      That returns 1 if $not_exposed_reason is defined. I doubt that's what the OP wants.
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        Oops, you are of course right.

        return $not_exposed_reason // 'No exposed reason';

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