Grzegorz Kossakowski skrev:
Vadim Gritsenko (JIRA) pisze:
Vadim Gritsenko commented on COCOON-2110:
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Don't we have a history of using #{foo} for jxpath and ${foo} for
jexl? Doing it differently
would just result in more confusion. I'd rather have it more uniform
throughout.
Actually, such syntax is supported[1] in our code for almost two years
now.
The new syntax is supported but it is plugable and the default settings
is using the old syntax. I didn't find any detailed design discussion
about the design in the archives, the idea is suggested in
http://marc.info/?l=xml-cocoon-dev&m=110651769909483&w=2.
For the actual implementation, the parsing of a string with embedded
expression calls (a string template) is plugable using the interface
o.a.c.template.expression.StringTemplateParser. The current syntax is
handles by JXTGStringTemplateParser and the new one by
DefaultStringTemplateParser. The choice of string template parser is
done in
http://svn.apache.org/repos/asf/cocoon/trunk/blocks/cocoon-template/cocoon-template-impl/src/main/resources/META-INF/cocoon/avalon/cocoon-template.xconf.
The whole string template mechanism (the package
o.a.c.template.expression) could preferably be reused in the sitemap as
well. To do this the package needs to be moved to the core
(cocoon-expression-language) and refactored a little bit, the
dependencies on o.a.c.template.environment.ParsingContext and
o.a.c.template.environment.ErrorHolder needs to be removed and a more
appropriate package name should be found.
...
To sum up, new syntax has been introduced during refactoring of Template
block and since community already voted to switch to refactored code it
also voted for new syntax.
The vote was not about removing the current syntax. It was about
switching default implementation of the JXTG concept.
Speaking about myself I prefer much more language prefixes and I think
we should go for it. The question that we need to answer is if we want
to support #{} syntax in sitemap? Since it was never there I don't think
it makes sense to do so.
Using the string template mechanism in the sitemap we get the current
JXTG syntax for free, but I would advice users to not use it.
I would prefer to just create migration guide that would clarify current
situation of expressions evaluation and would advice to use new syntax
everywhere. Also, switching to new syntax is really trivial, it involves
find & replace operation based on simple regexp. Is it a really big deal
if it's well described?
I'm all for recommending using the new unified expression mechanism and
for having a migration guide. But I'm -1 for forcing people to switch
immediately, especially as we already have a mechanism for making the
syntax plugable.
/Daniel
