PROPOSAL: Auto-assignment Parameters (original) (raw)

james lowden jl0235 at yahoo.com
Wed Mar 25 10:39:36 PDT 2009

Shouldn't it still be possible to infer, as in:

public data class Foo {

private final int must_be_positive;

public Foo (this.must_be_positive) throws SomeException { if (must_be_positive < 0) throw new SomeException ("It wasn't positive"); }

}

-JL

--- On Wed, 3/25/09, Mark Mahieu <markmahieu at googlemail.com> wrote:

From: Mark Mahieu <markmahieu at googlemail.com> Subject: Re: PROPOSAL: Auto-assignment Parameters To: jl0235 at yahoo.com Cc: coin-dev at openjdk.java.net Date: Wednesday, March 25, 2009, 12:33 PM Hi James,

I looked into inferring the parameter types, and while it does work quite well for 'brain-dead' POJO classes, it was not so great when you actually want to put some real code in the constructor, for example to throw an exception if a parameter value is not valid. The auto-assignment proposal is very much aimed at helping programmers with code they actually have to write (and therefore read and maintain), rather than just generate. If it happens to help with the latter as well, that's great. Mark

On 25 Mar 2009, at 13:41, james lowden wrote: > > I'd like to see both. Auto-getters/setters/equals/etc. would be really, really nice, but it would also be valuable to have a way of specifying a variety of different constructors to generate, which Mark's proposal would allow for. Example: > > public data class Foo { > private final int x; > private final int y; > private final String foo; > > public Foo (this.x) {} > > public Foo (this.foo, this.y) {} > } > > > (I eliminated the types from the automagical constructors, as they can be inferred by the compiler.)

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