Template Toolkit: silencing pop() and the other list virtual methods

[jbullock35]

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 %] 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 %] 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) %] 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.

[PodMaster]

'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 %]

[holli]

You can try

[% CALL list.pop %]

or

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

The latter is untested.

[PodMaster]

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]);).

[EvanCarroll]

Try this:

    [% list = [1, 2, 3] %]
    [% undef = list.pop %]

If it gives you a warning you might have to improvise with something of this like:


    [% [undef] = list.pop %]

[jbullock35]

Thanks to all. These replies are quite helpful.