Template::Toolkit: defined on aggregate item vs. defined on variable

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

Template::Toolkit 2.24 behaves weird when I store an aggregate item to a variable. The result of defined is not quite consistent. Look:

tpage <<EOF
[% group= ["test string"]; g = group.1 %]
[% IF g.defined != group.1.defined %]Seems like a bug![% END %]
EOF
Seems like a bug!
[download]

defined appears to behave like exists($ttstash{var}). The doc is inconsistent in that they tell about a value, not about a variable. The variable is assigned to, defined in this sense, but it is assigned an undefined value.

Isn't that a bug to report?

Comment on Template::Toolkit: defined on aggregate item vs. defined on variable Select or Download Code

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Re: Template::Toolkit: defined on aggregate item vs. defined on variable by choroba (Cardinal) on Aug 05, 2016 at 12:35 UTC
Weird indeed. Same in 2.26. ($q=q:Sq=~/;[c](.)(.)/;chr(-\|\|-\|5+lengthSq)`"S\|oS2"`map{chr \|+ord }map{substrSq`S_+\|`\|}3E\|-\|`7**2-3:)=~y+S\|`+$1,++print+eval$q,q,a, [download]	[reply] [d/l]
Re: Template::Toolkit: defined on aggregate item vs. defined on variable by beech (Parson) on Aug 05, 2016 at 17:46 UTC
arrays start with 0, so if you add another element, .1 is defined, so I think its not a bug `$ tpage tt2-defined-bug.txt group 1 g 1 group.0 1 group.1 1 no bug $ cat tt2-defined-bug.txt [%# tpage --compile_dir=goner tt2-defined-bug.txt -%] [% group= ["one","two"]; g = group.1 %] group [% IF group.defined %] 1 [% ELSE %] 0 [% END %] g [% IF g.defined %] 1 [% ELSE %] 0 [% END %] group.0 [% IF group.0.defined %] 1 [% ELSE %] 0 [% END %] group.1 [% IF group.1.defined %] 1 [% ELSE %] 0 [% END %] [% IF g.defined != group.1.defined %]Seems like a bug! [% ELSE %]no bu +g[% END %]` [download]	[reply] [d/l]
Re^2: Template::Toolkit: defined on aggregate item vs. defined on variable by choroba (Cardinal) on Aug 05, 2016 at 22:11 UTC
> so if you add another element, .1 is defined The question is why `g.defined != group.1.defined` when the array has one element only. ($q=q:Sq=~/;[c](.)(.)/;chr(-\|\|-\|5+lengthSq)`"S\|oS2"`map{chr \|+ord }map{substrSq`S_+\|`\|}3E\|-\|`7**2-3:)=~y+S\|`+$1,++print+eval$q,q,a, [download]	[reply] [d/l] [select]
Re^3: Template::Toolkit: defined on aggregate item vs. defined on variable by beech (Parson) on Aug 05, 2016 at 22:26 UTC
Because arrays start at 0? So group.1 is not defined? And the condition is true? `if( 1 ne "") { print "Seems like a bug! BUT IT IS NOT BUG\n"; }` [download]	[reply] [d/l]
Re^4: Template::Toolkit: defined on aggregate item vs. defined on variable by choroba (Cardinal) on Aug 05, 2016 at 22:40 UTC
Re^5: Template::Toolkit: defined on aggregate item vs. defined on variable (STRICT) by beech (Parson) on Aug 06, 2016 at 00:57 UTC
Re^2: Template::Toolkit: defined on aggregate item vs. defined on variable by flowdy (Scribe) on Aug 05, 2016 at 21:18 UTC
In general you're right. In this case, I just posted a simplified example to pm. In my real-word situation I have to tell apart defined or undefined second part of a tuple in view logic. This is where the shown weirdness taught me better not to give long.paths.through.data.structures simple names to use more than once. Or at least not to include the tail component in the assignment.	[reply]