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https://issues.apache.org/jira/browse/FREEMARKER-73?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16186841#comment-16186841
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Ondra Žižka edited comment on FREEMARKER-73 at 9/30/17 3:22 AM:
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If I use {{sometimesNull!?sequence}}, that would give me {{""?sequence}} and
thus error, then? How could I get an empty sequence rather than error? Did you
mean {{sometimesNull![]?sequence}} ?
Also, before I open an issue, what would be your view on a.very.long.expr!!
being a shorthand for {{(a.very.long.expr)!}} ? The effect of !! would go back
to the "root" of the expression, i.e. where the part the !! comes after
started. Not sure if that would have clear enough rules, though.
Anyway, you're right. Type magic is a bad idea.
The thing is that I have highly unpredictable models, deep models where things
can be missing almost at any level (It's a graph traversed through method or
getter calls). And handling the missing cases is a large part of FM template
code. Although it got a lot better with few recent changes. (The Iterators
change helped a lot.)
I will come up with something better ;)
was (Author: pekarna):
If I use {{sometimesNull!?sequence}}, that would give me {{""?sequence}} and
thus error, then? How could I get an empty sequence rather than error? Did you
mean {{sometimesNull![]?sequence}} ?
Also, before I open an issue, what would be your view on a.very.long.expr!!
being a shorthand for {{(a.very.long.expr)!}} ?
Anyway, you're right. Type magic is a bad idea.
The thing is that I have highly unpredictable models, deep models where things
can be missing almost at any level (It's a graph traversed through method or
getter calls). And handling the missing cases is a large part of FM template
code. Although it got a lot better with few recent changes. (The Iterators
change helped a lot.)
I will come up with something better ;)
> ?seq to convert some models to a sequence
> -----------------------------------------
>
> Key: FREEMARKER-73
> URL: https://issues.apache.org/jira/browse/FREEMARKER-73
> Project: Apache Freemarker
> Issue Type: Bug
> Components: engine
> Affects Versions: 2.3.26-incubating
> Reporter: Ondra Žižka
> Fix For: 2.3.27-incubating
>
>
> The objects I feed to FreeMarker often cotain {{Iterator}}s rather than
> {{Collection}}s.
> While it's quite easy to write a FreeMarker function
> {{iteratorToList(Iterator)}}, it would be convenient to have the following:
> A built-in that would convert various models to a sequence. Could be named
> {{?seq}} or {{?sequence}}.
> Usage:
> {code}<#assign foo = myIterable?seq>{code}
> {code}<#assign foo = myIterator?seq>{code}
> * A sequence would stay intact.
> * An {{Iterable}} wrapped in FM model would become internally a {{List}} -
> all elements consumed and stored.
> For me, other cases are not that important, but with some imagination, other
> models could also leverage it, like,
> * A {{Stream}} could be also turned into a {{List}}.
> * A hash could turn into a sequence of key/value pairs. That could be useful
> for debugging purposes.
> I am not sure if I didn't propose that already, but I could only find
> FREEMARKER-62.
> Thanks for considering.
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