Re: processing a macro from a Freemarker user-defined directive

Wednesday, November 10, 2010, 6:44:18 PM, Rebecca Younes wrote:

> Hello,
>
> I am trying to write a Freemarker directive in Java that will
> process a macro in a template, rather than the entire template. Is
> there a way to do this? I can see how to get the macro using
> Template.getMacros(), but I do not see a method of Macro that would
> allow me to process that.

Not like I ever tried to do this, but I'm pretty certain that no
public API-s exist to call a macro from Java. It's kind of finny,
because you can easily call other macros when you implement a macro in
FTL, yet you can't do that when you implement similar stuff in Java
(i.e. a TemplateDirectiveModel), as far as I see. Anyway, it's all
what you need, a plain equivalent of <@someMacro /> but from Java?

(I haven't done much programming in FreeMarker, but I think I could
implement that, calling macros from Java, and I also have the
authority do such things. Unfortunately there is a good chance that I
wont find much time in the foreseeable future... and Jonathan and
Attila seems to be out. So I just can't promise anything.)

> The Freemarker/Velocity comparison at
> http://freemarker.sourceforge.net/fmVsVel.html states:
>  You can capture the output of an arbitrary part of the template into a context variable.

That "arbitrary" has to be enclosed between explicit tags. Like

  <#assign blah>
    ... the arbitrary part ...
  </#assign>

This captures the output printed between the two tags into the "blah"
variable. Similarly, a TemplateDirectiveModel can capture the output
generated between that calling start- and end-tags, into whatever it
wants to. I have seen some (like Nuxeo developers) used this for
defining named "fragments" or "multiple bodies". Kind of a hack IMO,
as it involves that extra buffering, but then, sometimes it's the best
compromise.

>  You can interpret arbitrary context variable as if it were a template definition.

That refers to whateverString?interpret. So there you still need an
expression that evaluates to the template snippet (as a string) that
you want to run. Plus, you can't call built-ins (?thing) from Java
either... (again, for no good reason IMO, it just doesn't have any
public API apparently).

> This sounds like what I am trying to do, but I don't see how to do it.

Well, what's exactly your goal?

> Thanks.
>
> Rebecca Younes

-- 
Best regards,
 Daniel Dekany


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