I think it would add consistence… everywhere else types can be inferred… why not here
> On May 10, 2016, at 12:02 PM, Sam Dods via swift-evolution > <[email protected]> wrote: > > I propose that function argument types could be omitted in the same way as > variable and property argument types are omitted when they are set at point > of definition. > > At present the type of properties and variables can be inferred as below: > > class EvolutionManager { > let proposalManager = ProposalManager() // type is inferred > > func proposeTopic(topic: String) { > let evolution = Evolution(topic: topic) // type is inferred > proposalManager.proposeEvolution(evolution) > } > } > > However, function arguments cannot be inferred, as below: > > class EvolutionManager { > func proposeEvolution(evolution: Evolution, proposalManager = > ProposalManager()) { // compiler error, cannot infer type > proposalManager.proposeEvolution(evolution) > } > } > > It's a nice feature of the language that the type can be inferred for > properties and variables, so I don't see any reason not to allow the same for > function arguments. It allows for more concise code, and adds consistency > with other language features. And I don't personally think it would make our > code any harder to read. > > There are of course some cases where the type cannot be inferred, i.e. when > the type should actually be a protocol type and the default value is a > concrete type. Consider the following: > > protocol ProposalHandler { > associatedType P : Proposable > propose(p: P) > } > > class EvolutionManager { > // the type would be inferred as the concrete type `ProposalManager` and > could not be > // called with any other argument type that conforms to the > `ProposalHandler` protocol, > // as may have been the intention > func proposeEvolution(evolution: Evolution, proposalHandler = > ProposalManager()) > > // instead it should be written as follows: > func proposeEvolution(evolution: Evolution, proposalHandler: ProposalHandler > = ProposalManager()) > } > > But this is the same for properties and variables, so it should not be a > reason to not allow inferring of function arguments. For example: > > class EvolutionManager { > // the property is inferred as the concrete type `ProposalManager` and may > not > // be set to any other value of type that conforms to the `ProposalHandler` > protocol, > // as may have been the intention. > var proposalHandler = ProposalManager() > > // instead it should be written as follows: > var proposalHandler: ProposalHandler = ProposalManager() > } > > What do people think of this? > > It would have no impact on existing code, and it's not the kind of thing that > needs an alternative solution. > > > _______________________________________________ > swift-evolution mailing list > [email protected] > https://lists.swift.org/mailman/listinfo/swift-evolution _______________________________________________ swift-evolution mailing list [email protected] https://lists.swift.org/mailman/listinfo/swift-evolution
