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From Paolo Di Tommaso <paolo.ditomm...@gmail.com>
Subject Re: List and GString
Date Thu, 26 May 2016 21:52:20 GMT
Looking in the GString implementation I noticed that it call the
InvokeHelper.write
<https://github.com/apache/groovy/blob/master/src/main/org/codehaus/groovy/runtime/InvokerHelper.java#L500>
method.

I've tried implementing a DelegatingMetaClass
<https://objectpartners.com/2013/07/30/customizing-mop-in-groovy/> but it
does not work. At the end of the day it should to be possible to use
meta-programming to override Java compiled code.

Maybe the trick you are mentioning is ExpondoMetaClass.enableGlobally
<http://docs.groovy-lang.org/latest/html/api/groovy/lang/ExpandoMetaClass.html#enableGlobally%28%29>
?


Is there any other possible workaround ?


Cheers,
Paolo


On Thu, May 26, 2016 at 11:02 PM, Emmanuel Rosa <goaway1000@gmail.com>
wrote:

> The rendering is actually produced by InvokerHelper:
> https://github.com/apache/groovy/blob/master/src/main/org/codehaus/groovy/runtime/InvokerHelper.java#L123
>
> I tried overriding it with a category and also via the metaClass, but
> neither worked. I recall some kind of trick that’s needed when using the
> metaClass with some classes, to get it to take, but I don’t remember the
> details. :(
>
> On May 26, 2016, at 2:06 PM, Paolo Di Tommaso <paolo.ditommaso@gmail.com>
> wrote:
>
> Dear all,
>
> I have a use case in which I need to override the `toString` method of a
> custom List class and use it when interpolating that list object in a
> GString.
>
> It turns out the Groovy uses its own formatting methods for List and other
> structures, so the my custom `toString` is simply ignored.
>
> To explain it better take in consideration this example:
>
> class MyList extends ArrayList {
>
>   String toString() {
>     this.join('-')
>   }
>
> }
>
>
> def x = new MyList()
> x << 1 << 2 << 3
>
> assert x.toString() == '1-2-3'
> assert "$x" == '1-2-3'
>
> Assertion failed:
> assert "$x" == '1-2-3'
>          |  |
>          |  false
>          [1, 2, 3]
>
> The second assertion fails for the reason said above. Now I'm wondering it
> there's any way to override somehow the GString default rendering mechanism
> in such a way I can inject my own formatting rule for my custom class.
>
> Any suggestion is appreciated.
>
>
>
> Cheers,
> Paolo
>
>
>
>
>

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