Re: Continue Eclipse Freemarker DLTK?

2013/7/29 Daniel Dekany <[email protected]>

> Monday, July 29, 2013, 3:57:38 PM, Angelo zerr wrote:
>
> > Hi Daniel,
> >
> [snip]
> > OK, so I think branch should be named with *-debug or* -tools becaus
> it's not linked to dltk.
>
> (Sure, it could be "-tools". It's linked to the DLTK *development*, as
> it will be only merged back when the DLTK plugin is released.)
>

Ok, is it possible for you to create this branch if you start something
aboute the debugger?
I'm not a big expert with Git.


>
> > I would like that Freemarker improves :
> >  * debugger (add any debugger service,
> >  add stepping features,
>
> Yip.
>
> > fix bug with debug unsert ftl
>
> Which bug is that?
>

It was a long time, but if I remember when you write a.ftl which contains
<#include b.ftl > directive,and if you set a a breakpoint in the b.ftl and
you debug the a.ftl,
debugger should open b.ftl and I needed filename from the breakpoint to
retrieve it.

>
> BTW, I have noticed that you have extended the DebugBreakpoint AST
> node so that it can suspend after its enclosed expression (as opposed
> to before it, which is how it's done normally), and that meant to be
> used to support adding break-points on end-tags (</#...>, </@...>). I
> think we need not allow putting break-points on end-tags, similarly as
> we don't allow it on comments and such. An end-tag is purely
> parse-time thing, a syntactical device for marking the end of a block
> for the *parser*. Like, if you step through a template with debugger,
> the curret line never will by an end-tag. Yet a break-point there will
> trigger? But I'm not saying it's impossible to do. It's just that it's
> not essential. In theory, such a breakpoint should trigger after the
> last *nested* instruction was executed, unless that was a #break or
> #return. (I guess it's not what the current implenentation does.)
> Like, if you put a break-point on </@foo>, and you will see some HTML
> in the output where </@foo> was, you expect the breakpoint to trigger
> before that HTML is printed. With similar logic, for #list, the
> end-tag breakpoint should trigger after each cycle. Also a nested
> #continue should trigger it. Maybe the easiest way of implementing
> this is replaceding the TemplateElement.nestedBlock with a DebugBreak,
> only, some elements have a TemplateElement.nestedElements List
> instead... and actually a directive doesn't have to use any of those
> for its nested contents. So I suspect it's not trivial to do
> correctly. (Implementing step-into on and end-tag also can be tricky.)
>

OK, if I remember I have modified the DebugBreak to set a breakpint in the
end of the #if (as you have explained).
You can remove that if you wish.


>
> > (Breakpoint should stores too filename (the full path of the template)).
>
> You mean, the template name (TemplateLoader-relative path) is not
> enough, you need an absolute local filename associated with the
> breakpoint?


Yes it that, but I could retry again to give you more info, if you wish.


> Will that file name by set by the plugin, and will only be
> used by the plugin? I see no problem with that then, although I wonder
> if it would be useful to simply allow associating an arbitrary
> serializable object with a Breakpoint. Then that object could be a
> java.io.File, or a JavaBean that stores more info that's useful for
> the IDE to come back when the suspension event occurs.
>

Perhaps it's a good idea to have a "data" object attached to the
breakpoint?

>
> >  * syntax errors (add start/end offset info of the token)
>
> Tokens do have start/end line and column. Is it buggy or something?
> AST nodes (TemplateObject-s) also have start/end location, except when
> a constant expressions is substituted with a plain Java objects (like
> String).
>
For the moment I have line and column information. But it seems that I need
start and end offset to highlight the error.

>
> >   parser should be tolerant to displays several errors and build an
> >   AST even if they are errors.
>
> We will see... If nothing else, I hope I can make the parser to skip
> until the end of the FTL tag, then make a ElementWithParsingError AST
> node out of it. The lexel also will have to survive lexical errors, of
> course.
>
Cool.

>
> >> I guess static DebuggerService.getInstance(), when first called,
> >> should check the "freemarker.debug.debuggerService" system property,
> >> which had to be something like "new
> >> com.example.SomeDebuggerService(true) { password = 'qweqwe', port =
> >> 1234 }" (where the { ... } section sets JavaBeans properties). (This
> >> also means that we don't need extra properties like
> >> "freemarker.debug.password".)
> >
> > IMHO, I'm not a big fan to set a system property valeu which contains
> some java code  "new
> > com.example.SomeDebuggerServic.."
> >
> > I think we should have a DebuggerServiceRegistry which is enable to
> > returns an instance of DebuggerService according configuration.
> >
> > I havei mplemented this idea in my private commit
> >
> https://github.com/angelozerr/freemarker/commit/fb604a707e7d88e98f19bd0f40cbccce03080e19
> > by using SPI like I have suggested you.
> >
> > You can see test at
> >
> https://github.com/angelozerr/freemarker/blob/fb604a707e7d88e98f19bd0f40cbccce03080e19/src/test/java/freemarker/debug/DebuggerServiceRegistryTest.java
> >
> > The basic idea is to register debugger service provider with SPI
> > and get the well debugger provider according the system properties
> > by calling DebuggerServiceRegistry#getService() .
> > The Configuration#getDebuggerService() checks fi there are debugger
> > service setted (usefull for IDE) and if it's null,  use
> > DebuggerServiceRegistry#getService() .
>
> Well, it can work, but I would put some questions:
>
> - What are the advantatges of the SPI approach over the approach that
>   only uses properties (the one I have proposed)?
>

It's a "standard" mean to retrieve some service with Java5/Java6.

>
> - If I provide "freemarker.debug.password", that will make most
>   DebuggerService "accessible", how does the user contol which
>   implementation will be choosen (or why is it not a problem)?
>
OK, we could add a key in the property like -DdebuggerService=rmi to select
the rmi debugger.

>
> - Isn't it problematic that we are using the class-loader of FreeMarker
>   to find the SPI implementations? If FreeMarker comes from a more
>   generic directory than the SPI implementation, it won't be found, I
>   think. Then we won't even give an error, but fall back to
>   RMIDebuggerService (unlike in the properties-only solution).
>
The SPI implementations should be stores in the same classpath than
Freemarker. For OSGi context, you must create a fragment linked to the
Freemarker
 which contains the SPI implementation. We use SPI with XDocReport which
works in OSGi context to register document kind service (docx, odt,)
converter type (docx->pdf, docx->html, etc)
and it works great.

>
> - Is it setting different DebuggerService-s per Configuration useful?
>   Like, does it have a known real-world use-case?
>
For IDE, its useful. In my case I can debug 2 ftl. Each ftl are linked to a
Configuration. So each Configuration must have a dbgp debugger.

>
> > If you like it, I will clean my code and create a pull request.
>
> As of the clean-up, DebuggerServiceRegistry strikes me as needless,
> unless it will actually become a registry in the future (in which
> case, what will ot do?). Now all it does is getting a "default"
> ServiceRegistry found via the SPI API. That could be done in
> DebuggerService.getInstance().
>

In my case DebuggerService is an interface and not a class, that's why I
have created  DebuggerServiceRegistry

Note I have not used directly ServiceRegistry (Java6). I use my
JDKServiceLoader class (that I have developped for XDocReport)
to support Java5 and Java6.

>
> And we should mind the concurrency issues, like getInstance() will
> have to use synchronization of course (or use volatile tricks, under
> Java 5+).
>
> Speaking of which... the way the DebugBreak is inserted (that's
> Attila's code I'm ralking about) strikes me as very much
> thread-UNstafe.
>
> Last not least, can you give me *prioritized* list of what will you
> need (of the things that probably I will implement).
>

My big need is to use my dbgp debugger service. So it should be cool if you
provide this API (my pull request and commits was just to give you some
ideas, ut don't hesitate to do
other thing). I will adapt my DLTK code with your API.

Regards Angelo

>
> > Regards Angelo
>
> --
> Thanks,
>  Daniel Dekany
>
>
>
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