jbullock35 has asked for the wisdom of the Perl Monks concerning the following question:

A TT2 curiosity: pop does what it always does—but when I have template code embedded in HTML, it also inserts the popped value into my HTML, causing it to be displayed on screen. For example,
    [% list = [1, 2, 3] %]
    [% list.pop %]

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removes "3" from the list and inserts it into my HTML. I don't want it to insert anything into my HTML. I just want the list to contain one less value. I see a lot of ways to do this, e.g.,
    [% list = [1, 2, 3] %]
    [% p = list.pop %]

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but I don't like any of them. The example I've provided is unsatisfactory because I've no use for the popped value. I would use something like
    [% list = [1, 2, 3] %]
    [% list = list.slice(0,1) %]

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but I won't always know the length of the list in advance. Isn't there a simple standard way to do what I want?

Many thanks. I searched the TT mailing list but couldn't find anything speaking to this.

Replies are listed 'Best First'.
Re: Template Toolkit: silencing pop() and the other list virtual methods
by PodMaster (Abbot) on Dec 05, 2005 at 07:44 UTC
    'perldoc Template::Manual::Directives'
    CALL

    The CALL directive is similar to GET in evaluating the variable named, but doesn't print the result returned. This can be useful when a variable is bound to a sub-routine or object method which you want to call but aren't interested in the value returned. 

    # run tpage tt.just.pop.pl
# expect no numbers
OUTPUT: [% list = [1, 2, 3] %][% CALL list.pop %]

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    MJD says "you can't just make shit up and expect the computer to know what you mean, retardo!"
    I run a Win32 PPM repository for perl 5.6.x and 5.8.x -- I take requests (README).
    ** The third rule of perl club is a statement of fact: pod is sexy.

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Re: Template Toolkit: silencing pop() and the other list virtual methods
by holli (Abbot) on Dec 05, 2005 at 07:54 UTC
    You can try 
    [% CALL list.pop %]

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    or 
    [% PERL %]
$stash->get('list')->pop;
#or maybe
#pop @{$stash->get('list')};
[% END %]

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    The latter is untested.


    holli, /regexed monk/
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      If you enable debugging (DEBUG => 99), you can see how Template compiles the templates (that [% CALL list.pop %] becomes $stash->get(['list', 0, 'pop', 0]);, and [% list.pop %] becomes $output .=  $stash->get(['list', 0, 'pop', 0]);).

      MJD says "you can't just make shit up and expect the computer to know what you mean, retardo!"
      I run a Win32 PPM repository for perl 5.6.x and 5.8.x -- I take requests (README).
      ** The third rule of perl club is a statement of fact: pod is sexy.

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Re: Template Toolkit: silencing pop() and the other list virtual methods
by EvanCarroll (Chaplain) on Dec 05, 2005 at 07:12 UTC
    Try this: 
        [% list = [1, 2, 3] %]
    [% undef = list.pop %]

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    If it gives you a warning you might have to improvise with something of this like:
        [% [undef] = list.pop %]

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    Evan Carroll
    www.EvanCarroll.com
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Re: Template Toolkit: silencing pop() and the other list virtual methods
by jbullock35 (Hermit) on Dec 06, 2005 at 09:04 UTC
    Thanks to all. These replies are quite helpful.
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