A library to make the Guice internal DSL more Scala friendly.
The motivation for this library is the fact that, although Scala provides lots
of syntactic ways to create internal DSLs, when working with the Guice internal
DSL the Java code is both sorter an more readable. The main reason for this is
the absence of class literals in Scala. Instead of writing Service.class in
Scala we write classOf[Service] which is longer and less readable.
To address this problem sse-guice extends the interfaces of Guice's internal
DSL (defined in com.google.inject.binder) by adding a method that takes a
Manifest for each method that takes Class as a parameter. This allows us to
write:
bind[Service].to[ServiceImpl].in[Singleton]
instead of:
bind(classOf[Service]).to(classOf[ServiceImpl]).in(classOf[Singleton])
which is what we have to write when using Guice in Scala.
An added benefit of Manifests is that they not only allow us to get rid of
classes but also TypeLiterals. To define a binding for a generic type in
Guice (because of erasure) we have to construct a TypeLiteral. For example
to bind Validator[Registration] to RegistrationVSpec we have to write:
bind(new TypeLiteral[Validator[Registration]] {}).to(classOf[RegistrationVSpec])
Because Manifest also has information about the type arguments of a type when
using the methods that take Manifest as an argument sse-guice is able to
detect if the type has type arguments and construct a TypeLiteral
automatically. This allows us to write:
bind[Validator[Registration]].to[RegistrationVSpec]
and avoid the explicit creation of the TypeLiteral.
To use this library your Guice modules must extend the ScalaModule abstract
class instead of the AbstractModule. The ScalaModule adds methods and
overrides any methods that return binder interfaces to return the enhanced
interfaces of this library.
class MyModule extends ScalaModule {
def configure() {
bind[Service].to[ServiceImpl].in[Singleton]
bind[CreditCardPaymentService]
bind[PaymentService].to[CreditCardPaymentService]
bindConstant().annotatedWithName("port").to(8080)
}
}
Licensed under the Apache License, Version 2.0. See the LICENSE and NOTICE files for more information.