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From Remi Forax <fo...@univ-mlv.fr>
Subject Re: About the callable native lambda
Date Wed, 31 Jan 2018 10:10:13 GMT
You should try to reuse the LambdaMetaFactory instead of generating your own proxy,
- generating a proxy means you have a way to define a class in module that do not own, so
you have to use lookup.defineClass (or worst unsafe.defineClass), so you need to generate
an invokedynamic
- you can generate the proxy at compile time but in that case, you loose the fact that lambdas
reduce of disk footprint.
- JDK lambdas use a lightweight classloader so their code is unloaded if the lambda is GCed,
something which is hard to emulate with your own proxy,
- JDK lambdas consider captured values as really final fields trusted by the VM, again something
hard to emulate.

so (2) seems to be a better option.

cheers,
Rémi

----- Mail original -----
> De: "Daniel Sun" <realbluesun@hotmail.com>
> À: "dev" <dev@groovy.incubator.apache.org>
> Envoyé: Mardi 30 Janvier 2018 01:14:25
> Objet: About the callable native lambda

> Hi all,
> 
>      I'm trying to implement the callable native lambda(e.g.
> `Function<Integer, Integer> f = e -> e + 1; assert 3 == f(2);`), and there
> are 2 ideas come to my mind:
> 
> 1) Generate a proxy implementing the FunctionInterface(e.g. `Function`,
> `Consumer`, etc.) and a `Callable` interface(maybe we should create a new
> one), the proxy will delegate invocations of `call(Object... args)` method
> of `Callable` to the method of the FunctionInterface. As you know, `f(2)` is
> actually `f.call(2)`, so we need the method `call`.
> 2) Transform `f(2)` to `f.apply(2)`, we can get the target method name by
> the type of FunctionInterface. To make it clear, let's have a look at two
> example: `Function`'s method is `apply`, `Consumer`'s method is `accept`.
> 
>       I prefer the first way, but I want to get advice from you :-)
> 
>       In addition, have you any idea about the issue[1]? If you do not know
> off the top of your head, I'll have to investigate when I have some spare
> time. Any help is appreciated!
> 
> Cheers,
> Daniel.Sun
> 
> [1]
> https://github.com/apache/groovy/blob/native-lambda/src/main/java/org/codehaus/groovy/classgen/asm/sc/StaticTypesLambdaWriter.java#L136
> 
> 
> 
> --
> Sent from: http://groovy.329449.n5.nabble.com/Groovy-Dev-f372993.html

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