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From "Winnebeck, Jason" <Jason.Winneb...@windstream.com>
Subject RE: How to determine the equality of two closures?
Date Thu, 13 Apr 2017 14:28:29 GMT
Jochen, I had a use case that was very close to this that may or may not inspire bo zhang for
an alternative solution to closure equality. I had to rely on the Groovy implementation detail
that each Closure instance created from an expression at a line of code had the same class
(I did put this assumption in a unit test in my project so I'd know if that broke). That let
me create a DSL like AngularJS watches:

def person = [name: 'Jason', skills: ['groovy']]

person.watch( {skills} ) {oldVal, newVal ->
  println "person.$name's skills changed from $oldVal to $newVal"
}

To implement the watch method, I have a map of Class to watcher's state. So when the person.watch
expression is run again, the state is preserved from the last run, using the closure's class
as the key to recover the state. In this example, two watches with the same closure definition
would have two states. But if I put the two watch into a function, the closures would share
the same line of code and compare as "equal"

Jason

-----Original Message-----
From: Jochen Theodorou [mailto:blackdrag@gmx.org] 
Sent: Thursday, April 13, 2017 10:08 AM
To: users@groovy.apache.org
Subject: Re: How to determine the equality of two closures?



On 13.04.2017 15:56, bo zhang wrote:
> Hello everybody,
>
> I just have encountered a problem thus need your help. I want to treat 
> the following closures as "equivalent":
>
> Clousure c1={
> "This is a closure"
> }
>
> Clousure c2={
> "This is a closure"
> }
>
> assert closureEqual(c1,c2)

may I ask how you want to use that? I was thinking about this in the past, but I failed to
create a reasonable scenario in which I would need this.

> Apparently, even though all fields and methods (the internal bytecode) 
> are equal, c1 and c2 are still different classes (xxx_closure$1 and 
> xxx_closure$2). AFAIK, everything but name in these two classes are equal.
>
> Is there any possibilities to achieve my goal? Thank you very much.

right now, not no.

bye Jochen

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