how can SwingBuilder work?

[Ralph Johnson <jo...@cs.uiuc.edu>]

I'm working a program that was mostly written by someone else.

Some of the code I didn't write has things like

 public Object windowSpec() {

    return {

        def windowFrame = frame(attributes+[pack: true,
defaultCloseOperation: windowCloseAction]) {

            menuBar(this.menuBarSpec)

            widget([widget: builder.build(contentViewSpec),id: 'content'])

         }

        windowFrame.addWindowListener(this)

        windowFrame

    }

}


which gets called from a method that is sort of like


protected buildView() {

    builder.edt {

       view = builder.build(this.windowSpec())

    }

}


How can this work?   In particular, when windowSpec calls methods defined
by the SwingBuilder such as frame() and menuBar(), why are those considered
methods on the SwingBuilder and not on the class that contains the class
that contains this code?

There are a bunch of subclasses of the class with this code that works
correctly, but one where it doesn't, and I'm trying to figure out why.
But then I realized that I don't understand how it works at all.   Does the
method build() change the closure so that it will look in the SwingBuilder
for those methods?


-Ralph Johnson

Re: how can SwingBuilder work?

[Dinko Srkoč <di...@gmail.com>]

The method `build()` sets the Closure's delegate to `this` (`this`
being the instance of SwingBuilder) before it calls the Closure, so
the methods `frame` and `menuBar` indeed end up being invoked on the
SwingBuilder instance.

Cheers,
Dinko

On 8 April 2015 at 02:05, Ralph Johnson <jo...@cs.uiuc.edu> wrote:
> I'm working a program that was mostly written by someone else.
>
> Some of the code I didn't write has things like
>
> public Object windowSpec() {
>
>     return {
>
>         def windowFrame = frame(attributes+[pack: true,
> defaultCloseOperation: windowCloseAction]) {
>
>             menuBar(this.menuBarSpec)
>
>             widget([widget: builder.build(contentViewSpec),id: 'content'])
>
>          }
>
>         windowFrame.addWindowListener(this)
>
>         windowFrame
>
>     }
>
> }
>
>
> which gets called from a method that is sort of like
>
>
> protected buildView() {
>
>     builder.edt {
>
>        view = builder.build(this.windowSpec())
>
>     }
>
> }
>
>
> How can this work?   In particular, when windowSpec calls methods defined by
> the SwingBuilder such as frame() and menuBar(), why are those considered
> methods on the SwingBuilder and not on the class that contains the class
> that contains this code?
>
> There are a bunch of subclasses of the class with this code that works
> correctly, but one where it doesn't, and I'm trying to figure out why.   But
> then I realized that I don't understand how it works at all.   Does the
> method build() change the closure so that it will look in the SwingBuilder
> for those methods?
>
>
> -Ralph Johnson