PROPOSAL: Return 'this' (original) (raw)

Tom Hawtin Thomas.Hawtin at Sun.COM
Thu Mar 26 08:03:53 PDT 2009

Marek Kozieł wrote:

MAJOR ADVANTAGE: Simplification of “return this” statement. 'void' can be easy replaced with 'this'.

MAJOR BENEFIT(s): It would prevent NullPointerException, and make some 'builder' like interfaces look really clear and simple.

My problem with this is that it is an attempt to fix a hack due to a language problem with a language hack.

The underlying problem is that Java does not have a concise syntax for builders. The usual hack is for builders to return this and clients to use method chaining. This solution makes the hack easier. A better solution would be direct, explicit support for builders in some form.

Also the variant of this proposal that client-side reinterprets returning void to return this, would interfere to some extent with covariantly returning void when overriding a return of Void.

Tom Hawtin

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