[Feature request] Assisted inject in jdk8+ compiled with -parameters not requiring @Assisted

Introduction

I suggest to build a feature into guice that allows, when jdk8+ is used and -parameters flag is used with the compiler, guice can correlate the builder’s methods with the right constructor based only on the names of the parameters which get stored in the .class file. Allowing not requiring @Assisted at all. It could work like this: (Disclaimer: I don’t know guice internals in detail so I may mention some things wrong. Just point me out and I will fix)

The high level idea works like this:

Proposal

API

I have two possibilities, you may implement both or even suggest an alternative one

Possibility 1

marching by param name is done by (for example):

• new FactoryModuleBuilder().withParamNameMatching()

Possibility 2

Change FactoryProvider2’s constructor so it can get flags. So far, only has one flag. If matching by param name is enabled (see above how it is set) Alternatively, add a parameter to AssistedInject telling to match parameter names (E.g. @AssistedInject(“MatchInterfaceParamNames”))

Changes

Store param names

Intro

Change Key<T> or TypeLiteral<T> so it also stores the param name when it is present. Use:

• Parameter::isNamePresent()
• Method::getParameters gives the wanted Parameter[]

Alternative 1

FactoryProvider2:264 (281 in master branch):

• Let the Key<T> also store the names

Alternative 2

FactoryProvider2:259

• Change TypeLiteral<T> so it also stores parameter names

Manipulate param names

Manipulation 1

FactoryProvider2:496 (530 in master branch) -> FactoryProvider2.constructorHasMatchingParams:544

• before “// If any keys remain and their annotation is Assisted, we can’t use it.”
• If flag (mentioned above) is set and if Keys have parameter names: – Try matching the remaining name vs name — apply constructorKeys.remove(key) to the ones that matched

Manipulation 2

FactoryProvider2:498 (533 in master branch)

• "%s has more than one constructor annotated with @AssistedInject"… If the flag is active (either from the annotation or the method call), add the text: "Confirm that you are compiling the code with '-parameters' in a jdk8+ compiler that supports the flag"

[brunoais]

@dimo414 That’s my initial proposal with the limited knowledge I have of Guice. Please comment on it and call for attention to problems I didn’t notice.

[brunoais]

@ronshapiro Any comments about this?