Re: j2s-development] Nested Shells

[Zhou R. <jo...@sj...>]

Hi Sal,

GWT has its advantages: its generated *.js file size is much smaller 
than Java2Script's and its performance is very good. GWT's *.js is 
project dependent while Java2Script's *.js is library dependent. And the 
motivation of GWT's code generation is "to be as small and as efficient 
as possible" while Java2Script's motivation is "to provide same familiar 
Java APIs in JavaScript". And there are lots of other differences. In 
fact, GWT is great in many designs.

And about nested Shells: if a shell is designed to popup in a method B, 
the method B won't block later method C. For example:
public void methodB() {
    ...
    shell.open();
    while (...)
    ...
}
public void callMethod() {
    methodA();
    methodB();
    methodC();
}

methodC will always be called after methodB without blocking of the 
shell inside methodB, which is incorrect. And developer should avoid 
such method calls by wrapping them into callbacks of methodB.

If you popup shells orderly in the same method scope, Java2Script 
compiler will generate JavaScript correctly and shells will popup in 
correct order. For example:
public void aMethod() {
    ...
    shell.open();
    while (...)
    ...
    ...
    anotherShell.open();
    while (...)
    ...
}
anotherShell open only after the first shell is closed, which is correct.

You can inspect into the generated JavaScript to get the details.

Concept of nested Shells is considered a problem of  "Asynchronous 
Programming v.s. Synchronous Programming" in JavaScript. In JavaScript, 
no blocking by while loop or Thread.sleep or Object.wait exists. So 
synchronous programming should be converted into asynchronous 
programming. Java2Script compiler tries to help such conversions but 
won't help all. And I think nested Shells may not be implemented in 
release 1.0. If you find any possible ways to implement it, please 
discuss it on the mail list or implement it.

Regards,
Zhou Renjian

Sal Ferro wrote:
> Hi,
>  
> I'm new to the list. By the way - j2s is really cool, hands down the 
> best Javascript/RIA framework in existence currently, in my opinion.  
> I just hope sourceforge is ready for the traffic, when word spreads 
> and people come flocking to use this great new technology!!  I don't 
> understand the people comparing it to GWT.  Very different products, 
> GWT's scope and functionality kindof pales in my comparison (and no 
> eclipse integration! yuck!).
>  
> My question:  I noticed nested Shells are not supported yet.  Am I 
> missing anything, or is it just not yet implemented?  If not are there 
> any plan for implementing the feature yet? I am willing to 
> help implement it. 
>  
> I've become somewhat familiar with j2s sources, using it for several 
> weeks now, but a pointer or two on the 'suggested' approach to 
> implement it would help a little to be sure I don't go off into the weeds.
>  
> Thanks to the devs that make this library possible - I hope I can help 
> soon.
>  
> Thanks,
>  
> - Sal
>  
>  
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