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https://issues.apache.org/jira/browse/FREEMARKER-43?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Thomas Weidner updated FREEMARKER-43:
-------------------------------------
Description:
I have a lot of "tuple-like" types in my model. For example:
{code:java}
class Tuple {
int a;
float b;
String c;
}
{code}
In the template, i would like to iterate through the components of tuple using
#list. To implement TemplateSequenceModel or TemplateCollectionModel, I
basically need to create a temporary List object from the tuple, which seems
unnecessary.
Java 8 added a forEach model to java.lang.Iterable, which could be easily
implemented for Tuple without temporary objects:
{code:java}
// in Tuple
void forEach(Consumer<Object> c) {
c.accept(a);
c.accept(b);
c.accept(c);
}
{code}
Unfortunately, there is no such method in
TemplateSequenceModel/TemplateCollectionModel.
I propose to add such a method to the both classes and use this method in
IteratorBlock instead of handcrafted iteration. This would allow to more
efficient iteration for custom classes, while not imposing worse performance on
"standard" collections/interfaces (these also provide forEach in java8).
As this change would require java8, this API change would not break existing
implementations of Template*Model, as forEach could be implemented as default
interface method.
I could provide a prototype patch if requested.
Maybe as a separate bug, TemplateCollectionModel, TemplateSequenceModel should
both inherit from a new TemplateIterableModel which only provides forEach.
was:
I have a lot of "tuple-like" types in my model. For example:
{code:java}
class Tuple {
int a;
float b;
String c;
}
{code}
In the template, i would like to iterate through the components of tuple using
#list. To implement TemplateSequenceModel or TemplateCollectionModel, I
basically need to create a temporary List object from the tuple, which seems
unnecessary.
Java 8 added a forEach model to java.lang.Iterable, which could be easily
implemented for Tuple without temporary objects:
{code:java}
// in Tuple
void forEach(Consumer<Object> c) {
c.accept(a);
c.accept(b);
c.accept(c);
}
{code}
Unfortunately, there is no such method in
TemplateSequenceModel/TemplateCollectionModel.
I propose to add such a method to the both classes and use this method in
IteratorBlock instead of handcrafted iteration. This would allow to more
efficient iteration for custom classes, while not imposing worse performance on
"standard" collections/interfaces (these also provide forEach in java8).
As this change would require java8, this API change would not break existing
implementations of Template*Model, as forEach could be implemented as default
interface method.
I could provide a prototype patch if requested.
Maybe as a separate bug, Template{Collection,Sequence}Model should both inherit
from a new TemplateIterableModel which only provides forEach.
> Consider adding a Java 8 Style forEach method to
> TemplateCollectionModel/TemplateSequenceModel
> ----------------------------------------------------------------------------------------------
>
> Key: FREEMARKER-43
> URL: https://issues.apache.org/jira/browse/FREEMARKER-43
> Project: Apache Freemarker
> Issue Type: Improvement
> Components: engine
> Affects Versions: 2.3.25-incubating
> Reporter: Thomas Weidner
> Priority: Minor
>
> I have a lot of "tuple-like" types in my model. For example:
> {code:java}
> class Tuple {
> int a;
> float b;
> String c;
> }
> {code}
> In the template, i would like to iterate through the components of tuple
> using #list. To implement TemplateSequenceModel or TemplateCollectionModel, I
> basically need to create a temporary List object from the tuple, which seems
> unnecessary.
> Java 8 added a forEach model to java.lang.Iterable, which could be easily
> implemented for Tuple without temporary objects:
> {code:java}
> // in Tuple
> void forEach(Consumer<Object> c) {
> c.accept(a);
> c.accept(b);
> c.accept(c);
> }
> {code}
> Unfortunately, there is no such method in
> TemplateSequenceModel/TemplateCollectionModel.
> I propose to add such a method to the both classes and use this method in
> IteratorBlock instead of handcrafted iteration. This would allow to more
> efficient iteration for custom classes, while not imposing worse performance
> on "standard" collections/interfaces (these also provide forEach in java8).
> As this change would require java8, this API change would not break existing
> implementations of Template*Model, as forEach could be implemented as default
> interface method.
> I could provide a prototype patch if requested.
> Maybe as a separate bug, TemplateCollectionModel, TemplateSequenceModel
> should both inherit from a new TemplateIterableModel which only provides
> forEach.
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