On 19 Sep 2014 at 10:24:51, Thomas Mortagne
([email protected](mailto:[email protected])) wrote:
> #try
>
> was not possible ? (without parenthesis)
AFAIK it’s not possible since BLOCK directives in Velocity need parenthesis.
Thanks
-Vincent
> On Fri, Sep 19, 2014 at 12:04 AM, [email protected] wrote:
> >
> >
> > On 18 Sep 2014 at 19:41:56, [email protected]
> > ([email protected](mailto:[email protected])) wrote:
> >
> >> Hi Sergiu,
> >>
> >> On 18 Sep 2014 at 19:29:52, Sergiu Dumitriu
> >> ([email protected](mailto:[email protected])) wrote:
> >>
> >> > 1. I would rather add proper directives instead of macros and
> >> > uberspector hacks: http://stackoverflow.com/q/159292/620249
> >>
> >> Argh… I wanted that and I asked Thomas and he told me it wasn’t possible
> >> and I didn’t double check. I should have since I’ve now finished my
> >> implementation and redoing it as a directive means dumping what I’ve done
> >> a third time in the end. Anyway I agree that a directive is better so I’ll
> >> redo it.
> >
> > I’ve now implemented a directive and it’s so cool :)
> >
> > It’s so simple compared to what I had, I love it.
> >
> > Here’s the usage code now:
> >
> > #try()
> > #set($outputSyntax =
> > $xwiki.getAvailableRendererSyntax($request.outputSyntax,
> > $request.outputSyntaxVersion))
> > #if ($outputSyntax)
> > ## If the passed syntax is not an HTML-compatible syntax we need to
> > HTML-escape it so that it can be
> > ## displayed fine in HTML (since at the point this vm file is called we're
> > already inside an HTML page with
> > ## panels on the side, header, etc).
> > #set($syntaxType = $outputSyntax.type.toIdString())
> > #if (($syntaxType == "xhtml") || ($syntaxType == "html"))
> > #set ($renderedContent = $tdoc.getRenderedContent($outputSyntax))
> > #else
> > ## Make sure to print correctly the result when it's not HTML
> > #set ($renderedContent = "
$escapetool.html($tdoc.getRenderedContent($outputSyntax))
")
> > #end
> > #else
> > #set ($renderedContent = $tdoc.getRenderedContent())
> > #end
> > #end
> > …
> >
> > #if ("$!exception" != '')
> > #displayException($exception)
> > #else
> > $renderedContent
> > #end
> >
> > …
> >
> > I like it so much that I’m going to commit it and if someone doesn’t agree
> > I’ll revert the commit :)
> >
> > Thanks Sergiu
> > -Vincent
> >
> >> > 2. So far it has been the job of our scriptable wrappers to catch
> >> > exceptions, does this proposal mean that:
> >> > a. We should stop doing that and write try-catch logic in our
> >> > templates/scripts? IOW, catching exceptions in wrappers is a bad design
> >> > pattern?
> >>
> >> I’ve not answered this question because I don’t know yet. I think we’ll
> >> discover that as we start using the new try/catch. ATM I’m only planning
> >> to use it in contentview.vm.
> >>
> >> > b. We didn't do that enough, and as a workaround we're adding exception
> >> > handling in Velocity?
> >>
> >> Yes, that’s true. We now have both cases in our code (code throwing
> >> exceptions, like a lot of methods in Document, XWiki) and others catching
> >> exceptions.
> >>
> >> This proposals offers a finer-grained control in vm while not breaking
> >> backward compatibility. Any change in our script APIs would break
> >> compatibility (this is what I started doing before realizing it would
> >> break too many things)…
> >>
> >> FTR here’s what I have so far in term of usage, in contentview.vm:
> >>
> >> #try()
> >> #set($outputSyntax =
> >> $xwiki.getAvailableRendererSyntax($request.outputSyntax,
> >> $request.outputSyntaxVersion))
> >> #if ($outputSyntax)
> >> ## If the passed syntax is not an HTML-compatible syntax we need to
> >> HTML-escape it so that it can be
> >> ## displayed fine in HTML (since at the point this vm file is called we're
> >> already inside an HTML page with
> >> ## panels on the side, header, etc).
> >> #set($syntaxType = $outputSyntax.type.toIdString())
> >> #if (($syntaxType == "xhtml") || ($syntaxType == "html"))
> >> #set ($renderedContent = $tdoc.getRenderedContent($outputSyntax))
> >> #else
> >> ## Make sure to print correctly the result when it's not HTML
> >> #set ($renderedContent = "
> > $escapetool.html($tdoc.getRenderedContent($outputSyntax))
> > ")
> >> #end
> >> #else
> >> #set ($renderedContent = $tdoc.getRenderedContent())
> >> #end
> >> #catch()
> >>
> >> …
> >>
> >
> >> #if ("$!exception" != '')
> >> #displayException($exception)
> >> #else
> >> $renderedContent
> >> #end
> >>
> >
> >> …
> >>
> >>
> >> Thanks
> >> -Vincent
> >>
> >> > On 09/18/2014 09:28 AM, [email protected] wrote:
> >> > > Hi Devs,
> >> > >
> >> > > Example of a use case:
> >> > >
> >> > > * In contentview.vm we need to be able to catch when
> >> > > getRenderedContent() throws an exception in order to be able to still
> >> > > display the page title, content menu and last modification line. We
> >> > > want only the content part to display an error.
> >> > >
> >> > > I’ve tried implementing the following:
> >> > > * Modified Document.getRenderedContent() to not throw exceptions any
> >> > > more
> >> > > * I’ve added Document.setError() and getError()
> >> > > * Then added a #displayRenderedContent($renderedContent) velocimacro
> >> > > to display an error, calling Document.getError()
> >> > >
> >> > > However that’s no good because we have lots of places in our code (and
> >> > > in extensions we don’t control) that call getRenderedContent() and
> >> > > they expect the whole page rendering to fail in case of an error…
> >> > >
> >> > > Thus after discussing quickly on IRC and with Thomas we’d like to
> >> > > propose instead:
> >> > >
> >> > > * Add a new #try() velocimacro that would push a new empty List in the
> >> > > Execution Context to a Stack variable
> >> > > * Add a new uberspector that would, based on this flag do a try/catch
> >> > > around the method called (can be done easily by returning a custom
> >> > > VelMethod)
> >> > > * The uberspector catch would add the exception to the List in the
> >> > > Execution Context
> >> > > * Add a new #catch() velocimacro that would pop from the Stack in the
> >> > > Execution Context and that would set 2 variables in the Velocity
> >> > > Context:
> >> > > ** $exception: the first exception
> >> > > ** $exceptions: the list of all exceptions that happened between the
> >> > > #try() and #catch()
> >> > >
> >> > > The good part with this is:
> >> > > * No change in behavior to all existing code
> >> > > * Code that want to do something in case of error can do it using
> >> > > #try()/#catch() for java methods throwing exceptions (like
> >> > > getRenderedContent())
> >> > >
> >> > > Of course for the future we would need to decide if script services
> >> > > should stop doing try/catch or not but that’s another debate I’d
> >> > > prefer to separate from this thread.
> >> > >
> >> > > WDYT?
> >> > >
> >> > > Thanks
> >> > > -Vincent
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