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Date: Mon, 2 Oct 2017 05:10:00 +0000 (UTC)
From: =?utf-8?Q?Ondra_=C5=BDi=C5=BEka_=28JIRA=29?= <jira@apache.org>
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Subject: [jira] [Comment Edited] (FREEMARKER-37) ability to skip iteration
 in a list
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archived-at: Mon, 02 Oct 2017 05:10:10 -0000


    [ https://issues.apache.org/jira/browse/FREEMARKER-37?page=3Dcom.atlass=
ian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=3D1=
6187662#comment-16187662 ]=20

Ondra =C5=BDi=C5=BEka edited comment on FREEMARKER-37 at 10/2/17 5:09 AM:
----------------------------------------------------------------

I agree that just having {{<#continue>}} might lead to an unexpected/undefi=
ned behavior with things like counters, separators etc.

How about having {{<#continue>}} and {{<#skip>}} ?   {{<#continue>}} would =
count as item used (increment the counter), {{<#skip>}} would not. This wou=
ld pass the responsibility to decide whether to increment the counter or no=
t to the user. It makes sense, because the user knows whether he uses {{is_=
even_item}} for coloring table rows, and whether that was already taken car=
e of (then they would use {{<#continue>}}) or not (then he would use {{<#sk=
ip>}}).

I.e.

{code}
<#list 10..15 as num>
    <#if num =3D=3D 10>=20
        <#continue>
    </#if>
    <#if num =3D=3D 11>=20
        <#skip>
    </#if>
    [${num.index}] =3D=3D  ${num}, ${num.count} items passed, is_first =3D =
${num.is_first?c}
</#list>
{code}

This would print=20
2 =3D=3D 12, 1 items passed, is_first=3Dfalse  (I hope I computed right :)
...
Because the {{.counter}} would increment only if the loop is finished or co=
ntinued, {{is_first}} would derive from the {{counter =3D=3D 0}}.=20

Similarly, {{is_even_item}} and {{is_odd_item}} would check the counter rat=
her than index.

{{is_last}} would probably have to rely on {{index}}.

Similarly, separators could appear if {{couter > 0 and index < size-1}}, an=
d, well, the user would have to have some common sense not to expect the se=
parator appear if he uses {{<#skip>}} before {{<#sep>}}.=20


was (Author: pekarna):
I agree that just having {{<#continue>}} might lead to an unexpected/undefi=
ned behavior with things like counters, separators etc.

How about having {{<#continue>}} and {{<#skip>}} ?   {{<#continue>}} would =
count as item used, {{<#skip>}} would not. This would pass the responsibili=
ty to decide whether to increment the counter or not to the user. It makes =
sense, because the user knows whether he uses {{is_even_item}} for coloring=
 table rows, and whether that was already taken care of (then they would us=
e {{<#continue>}}) or not (then he would use {{<#skip>}}).

I.e.

{code}
<#list 10..15 as num>
    <#if num =3D=3D 10>=20
        <#continue>
    </#if>
    <#if num =3D=3D 11>=20
        <#skip>
    </#if>
    [${num.index}] =3D=3D  ${num}, ${num.count} items passed, is_first =3D =
${num.is_first?c}
</#list>
{code}

This would print=20
2 =3D=3D 12, 1 items passed, is_first=3Dfalse  (I hope I computed right :)
...
Because the {{.counter}} would increment only if the loop is finished or co=
ntinued, {{is_first}} would derive from the {{counter =3D=3D 0}}.=20

Similarly, {{is_even_item}} and {{is_odd_item}} would check the counter rat=
her than index.

{{is_last}} would probably have to rely on {{index}}.

Similarly, separators could appear if {{couter > 0 and index < size-1}}, an=
d, well, the user would have to have some common sense not to expect the se=
parator appear if he uses {{<#skip>}} before {{<#sep>}}.=20

> ability to skip iteration in a list
> -----------------------------------
>
>                 Key: FREEMARKER-37
>                 URL: https://issues.apache.org/jira/browse/FREEMARKER-37
>             Project: Apache Freemarker
>          Issue Type: Improvement
>            Reporter: Ivan Levchenko
>
> Sorely missing ability to skip through an iteration of a list and continu=
e on with the rest of the list. would like to write clean code like this:
> <#list collection as element>
>         <#if element.attr1 =3D=3D "some_value">=20
>                 <#continue />  <#-- skip over this item and run next item=
 in loop -->
>         </#if>
>     do stuff here
> </#list>
> Thanks!


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