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Date: Wed, 18 Feb 2009 11:24:02 -0800 (PST)
From: "Claude Brisson (JIRA)" <dev@velocity.apache.org>
To: velocity-dev@jakarta.apache.org
Subject: [jira] Commented: (VELOCITY-680) RFC: New #local directive that
 behaves like #set but puts things into local context in macro rendering
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    [ https://issues.apache.org/jira/browse/VELOCITY-680?page=3Dcom.atlassi=
an.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=3D12=
674753#action_12674753 ]=20

Claude Brisson commented on VELOCITY-680:
-----------------------------------------

> Basically, i don't want more directives for #setlocal and #setglobal supp=
ort. To my eyes, it's inflexible, non-extensible clutter, especially if we =
keep around config options like velocimacro.context.localscope to complicat=
e the possibilities.=20

I agree - if we find a nice way of specifying the context in #set, it's bet=
ter than multiplying the number of directives.
But why not just specify the scope as a second optional argument to #set, a=
s in :

#set( $foo =3D $bar, parse )=20

Visually complex syntaxes can really scare people coming from the world of =
the web design - brackets followed by parenthesis are really confusing.

> Depending on the implementation, this syntax might be extensible and allo=
w VelocityView contexts to recognize and handle things like:
> #set[request]( $foo =3D 'bar' )
> #set[session]( $foo =3D 'bar' )
> #set[application]( $foo =3D 'bar' )

Those ones already have a very natural syntax (which I didn't include in th=
e trunk to avoid having the tools depending on a too recent version of the =
engine - but, by the way, it's enough not to configure its use by default, =
so I'll include it!):

#set($request.foo =3D 'bar')
#set($session.foo =3D 'bar' )
#set($application.foo =3D 'bar' )

Since $request, $session and $application all are legitimate objects, I don=
't think we need something else.

Ah. Speaking of this, I think of another solution about the scoped syntax d=
ebate, which in fact is the one I like the most now that I think of it: the=
 tools approach.
Why not give each scope an object representing it, that is a $foreach, a $t=
emplate and a $macro? It looks like really very customizable (as users can =
inherit hose objects) and flexible. That would give things like:

#foreach($i in $collection)
  #set($foreach.foo =3D 'bar')
  #if($i =3D=3D 'I want to break out') $foreach.break() #end
  #if( $i =3D=3D 'red alert' ) $template.stop()
#end
#macro(mymacro) #set($mymacro.mylocal =3D 'bar') #end

etc...


> RFC: New #local directive that behaves like #set but puts things into loc=
al context in macro rendering
> -------------------------------------------------------------------------=
-----------------------------
>
>                 Key: VELOCITY-680
>                 URL: https://issues.apache.org/jira/browse/VELOCITY-680
>             Project: Velocity
>          Issue Type: New Feature
>    Affects Versions: 1.7
>            Reporter: Jarkko Viinam=C3=A4ki
>         Attachments: velocity-local-directive-1.1.patch, velocity-local-d=
irective.patch
>
>
> It would be very useful to be able to set variables that are in local mac=
ro scope. That is, they do not overwrite "global" variables and are thrown =
away after macro rendering. This would allow people to build macro librarie=
s that do not clash so easily with each other.
> There is some implementation of a "LocalDirective" in experimental/locald=
irective but I didn't quite get it and it doesn't follow the same syntax as=
 #set. I used a few minutes to hack together this alternative implementatio=
n which behaves exactly like #set but it puts things in local context only.
> There's only one test case since this is Request-for-Comments type of pat=
ch.

--=20
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