#macro recursion

[Jean-Marc Reynaud <JR...@rdfgroup.com>]

Is it possible for #macro()s to recurse?

 

I'm attempting recursion but the output is not as expected and I'm not
sure whether it's due to my code or whether recursion is not supported.

 

 

Kindest regards,

 

Jean-Marc Reynaud

 


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Re: #macro recursion

[ap...@recks.org]

Macro recursion works, but beware that velocity passes 
parameters as references to the original context - which
means that changing this variable within the macro 
changes it for the caller.

So recurse with depth first is tricky or imposible:
#macro( myMacro $foo )
  #myMacro( $foo + 1 )
  ... ## do something with $foo cannot work
#end

So you need to do:
#macro( myMacro $foo )
  #set( $bar = $foo )## dereference $foo
  ... ## use $bar here
  #myMacro( $bar + 1 )## recurse depth last
#end

Or use the #local directive (see the contrib area or wiki, 
and please check the exact usage syntax - I'm writing
out of my rememberabnce):
#macro( myMacro $foo )
  #local( $bar )
  #set( $bar = $foo )## dereference $foo
  #myMacro( $bar + 1 )## recurse depth first
  ... ## use $bar here
  #end
#end

I've used recursion once, and hope this knowhow helps.

Cheers,
Christoph

> Von: "Will Glass-Husain" <wg...@forio.com>
> An: "Velocity Users List" <ve...@jakarta.apache.org>
> Betreff: Re: #macro recursion
> Datum: Wed, 8 Mar 2006 09:01:00 -0800
> 
> Yes, but their are some pecularities about scoping.
> 
> Do you have this property set to true?
> velocimacro.context.localscope
> 
> I'm not experienced in Macro recursion, but I suggest you try that.  Maybe
> someone else would chime in who works with recursion macros.  Or check the
> archives.  (the topic has come up before).
> 
> WILL
> 
> 
> On 3/8/06, Jean-Marc Reynaud <JR...@rdfgroup.com> wrote:
> >
> > Is it possible for #macro()s to recurse?
> >
> >
> >
> > I'm attempting recursion but the output is not as expected and I'm not
> > sure whether it's due to my code or whether recursion is not supported.
> >
> >
> >
> >
> >
> > Kindest regards,
> >
> >
> >
> > Jean-Marc Reynaud
> >
> >
> >
> >
> > This transmission is confidential and intended solely for the person or
> > organisation to whom it is addressed. It may contain privileged and
> > confidential information. If you are not the intended recipient, you
> should
> > not copy, distribute or take any action in reliance on it. If you have
> > received this transmission in error, please notify the sender
> immediately.
> > Any opinions or advice contained in this e-mail are those of the
> individual
> > sender except where they are stated to be the views of RDF Group plc.
> All
> > messages passing through this gateway are virus scanned.
> >
> >
> >
> 
> 
> --
> Forio Business Simulations
> 
> Will Glass-Husain
> wglass@forio.com
> www.forio.com
> 

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Re: #macro recursion

[Will Glass-Husain <wg...@forio.com>]

Yes, but their are some pecularities about scoping.

Do you have this property set to true?
velocimacro.context.localscope

I'm not experienced in Macro recursion, but I suggest you try that.  Maybe
someone else would chime in who works with recursion macros.  Or check the
archives.  (the topic has come up before).

WILL


On 3/8/06, Jean-Marc Reynaud <JR...@rdfgroup.com> wrote:
>
> Is it possible for #macro()s to recurse?
>
>
>
> I'm attempting recursion but the output is not as expected and I'm not
> sure whether it's due to my code or whether recursion is not supported.
>
>
>
>
>
> Kindest regards,
>
>
>
> Jean-Marc Reynaud
>
>
>
>
> This transmission is confidential and intended solely for the person or
> organisation to whom it is addressed. It may contain privileged and
> confidential information. If you are not the intended recipient, you should
> not copy, distribute or take any action in reliance on it. If you have
> received this transmission in error, please notify the sender immediately.
> Any opinions or advice contained in this e-mail are those of the individual
> sender except where they are stated to be the views of RDF Group plc. All
> messages passing through this gateway are virus scanned.
>
>
>


--
Forio Business Simulations

Will Glass-Husain
wglass@forio.com
www.forio.com