Re: How to stop (w/o exception)

catch (StopException stop) {
    if !("graceful".equals(stop.getMessage()) throw stop;
}

That's where I am going, but FreemarkerServlet doesn't really give me a clear point to hook in.  This class could probably use a few simple refactorings like extract method and such at some point.  Some of the methods look like they are doing 6 different things.

Pre template process can do it, but the exception handling doesn't really work out...

        @Override
        public boolean preTemplateProcess(HttpServletRequest request,
                        HttpServletResponse response, Template template, TemplateModel model) {
                addMyStuffToModel();
                try {
                        process(request, response, template, model);
                } catch (TemplateException e) {
                        handleException(e);
                } catch (IOException e) {
                        handleException(e);
                } catch (ServletException e) {
                        handleException(e);
                }
                return false;
        }

        // servlet should have this as a protected method,
        // I could then just call super.process(..) in a try catch block.
        protected void process(HttpServletRequest request,
                        HttpServletResponse response, Template template, TemplateModel model)
                        throws TemplateException, IOException, ServletException {
                try {
                        template.process(model, response.getWriter());
                } catch (StopException e) {
                        if (!"graceful".equals(e.getMessage())) {
                                throw e;
                        }
                } finally {
                        postTemplateProcess(request, response, template, model);
                }
        }


        protected void handleException(Exception e) {
                LOG.error(e.getMessage(), e);
                // uh...
        }



Also it looks like that won't work anyway, the exception doesn't come back and I can't catch it...  Am I doing something wrong?


13:32:22,530 ERROR runtime:96 -
Encountered stop instruction

Cause given: graceful
graceful
The problematic instruction:
----------
==> stop [on line 4, column 9 in WEB-INF/inquiry/view.ftl] [on line 4, column 9 in WEB-INF/inquiry/view.ftl]
 in include "view.ftl" [on line 11, column 9 in WEB-INF/inquiry/index.ftl]
----------

Java backtrace for programmers:
----------
freemarker.core.StopException: graceful
        at freemarker.core.StopInstruction.accept(StopInstruction.java:73)
        at freemarker.core.Environment.visit(Environment.java:196)
        at freemarker.core.ConditionalBlock.accept(ConditionalBlock.java:79)
        at freemarker.core.Environment.visit(Environment.java:196)
        at freemarker.core.MixedContent.accept(MixedContent.java:92)
        at freemarker.core.Environment.visit(Environment.java:196)
        at freemarker.core.Environment.include(Environment.java:1378)
        at freemarker.core.Include.accept(Include.java:155)
        at freemarker.core.Environment.visit(Environment.java:196)
        at freemarker.core.MixedContent.accept(MixedContent.java:92)
        at freemarker.core.Environment.visit(Environment.java:196)
        at freemarker.core.Environment.process(Environment.java:176)
        at freemarker.template.Template.process(Template.java:232)
        at edu.upmc.ccweb.core.support.freemarker.FreemarkerServlet.process(FreemarkerServlet.java:168)
        at edu.upmc.ccweb.core.support.freemarker.FreemarkerServlet.preTemplateProcess(FreemarkerServlet.java:152)
        at freemarker.ext.servlet.FreemarkerServlet.process(FreemarkerServlet.java:424)
        at freemarker.ext.servlet.FreemarkerServlet.doGet(FreemarkerServlet.java:366)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:689)



-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Jonathan Revusky
Sent: Tuesday, February 26, 2008 1:03 PM
To: FreeMarker-user
Subject: Re: [FreeMarker-user] How to stop (w/o exception)

On Tue, Feb 26, 2008 at 6:48 PM, Newman, John W <[email protected]> wrote:
> Instead of the macro I'd just put it in an if statement.  Maybe I can try/catch stop exception in my servlet, but I may not always want to catch that.  There should be a [#abort /] directive or something to do that.

Well, one possibility is that you use [#stop "graceful"] when you
intend for the exception to be ignored. And then in the java code, you
could:

try {
   ....
   template.process(dataModel,out);
   ...
} catch (StopException stop) {
    if !("graceful".equals(stop.getMessage()) throw stop;
}

so you rethrow the exception unless the detail string associated with
it is "graceful".

In any case, Attila's suggestion of using a macro in conjunction with
#return also works internally by throwing an exception except that it
gets caught , so it unwinds to the point where the macro was called.
You know, again, AFAICS, the only way to jump out of an arbitrarilly
nested structure is by throwing an exception.


>
>
>
>
>  -----Original Message-----
>  From: [email protected] [mailto:[email protected]] On Behalf Of Attila Szegedi
>  Sent: Tuesday, February 26, 2008 12:44 PM
>  To: FreeMarker-user
>  Subject: Re: [FreeMarker-user] How to stop (w/o exception)
>
>  You could enclose your template body in a:
>
>  [#macro actuallyRenderThePage]
>  ...
>  [/#macro]
>  [@actuallyRenderThePage/]
>
>  and then use [#return] from within the macro body. Of course, that
>  doesn't address more complex situations, as stopping gracefully from
>  several levels of macros or includes. In these cases [#stop/] is the
>  only reliable mechanism -- you'll just have to catch and ignore it at
>  your point of Template.process() invocation...
>
>  Attila.
>
>  On 2008.02.26., at 17:44, Newman, John W wrote:
>
>  > Hi,
>  >
>  > I tried searching but sourceforge is down... I'm sure this has been
>  > discussed before.
>  >
>  >
>  > We have the [#stop /] directive which throws an exception.  Is there
>  > a way to stop processing gracefully?
>  >
>  >
>  > [#if somethingBad]
>  >    [#stopGracefully /]
>  > [/#if]
>  >
>  > Sure I could do
>  >
>  > [#if ! somethingBad]
>  >    Everything here
>  > [/#if]
>  >
>  > But I'm pretty sure there is a break or stop thing that should work
>  > here.  Just wondering, thanks.
>
>
>
>
>
>
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