Re: I don't understand why cfg.setObjectWrapper(new DefaultObjectWrapper()); must be used

Wednesday, June 18, 2008, 3:12:49 PM, Vañó Sempere, José Rafael wrote:

> Hello.
>
> I've seen something I don't understand in freemarker's documentation:
>
> Page
> http://www.freemarker.org/docs/pgui_quickstart_createconfiguration.html
> ("Create a configuration instance")
> says that
> cfg.setObjectWrapper(new DefaultObjectWrapper());
> must be used.
>
> I don't understant why cfg.setObjectWrapper(new DefaultObjectWrapper());
> is necessary.

FreeMarker was miss-designed earlier regarding the singleton wrapper,
so using it is not recommended anymore. It still works if you use
that, like earlier, but I show the current best practice in that
example.

> The default object wrapper is suposed to be a thread-safe singleton, isn't it?

Yes, but it's not read-only in the sense that you can change its
configuration settings. And that's what causes the problem... if
multiple independently developed system components use the singleton,
some may will re-configure it, and thus also re-configuring the
wrapper of the other components. Configuring the singleton should be
banned, but we can't fix it now as that would break many old
applications.

> By the way, I haven't seen that line in freemarker's examples.

Um... that's a problem.

> Thank you very much.
>
>   Jose
>
> P.S.: Sorry for my English.

-- 
Best regards,
 Daniel Dekany


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