On May 29, 2013, at 3:12 PM, Anthony Carrico <acarr...@memebeam.org> wrote:
> It seems like the purpose of #:constructor-name is to get the default
> contsructor out of the way,
It's really just to move from make-hello to hello for constructor names w/ easy
backward compatibility.
> so you can customize it:
>
> #lang racket
>
> (struct hello (a b c)
> #:constructor-name hello-rep
> )
>
> (define (hello) (hello-rep 1 2 3))
If you want to have constructors and/or selectors and/or mutators that aren't
standard, you may wish to use this pattern:
(define-values (constructor predicate selector)
(let ()
(struct my (you))
(values my my? (lambda (x) (displayln `(accessing the ,x struct)) (my-you
x)))))
But yes, this eliminates other things you may have.
-- Matthias
>
> But this gives the error:
> duplicate definition for identifier in: hello
>
> Work arounds:
> 1. Use a guard, but this restricts the signature of the constructor.
> 2. Use a module to manage the names, but this is annoying.
> 3. Fall back on the make-hello convention instead of using the
> struct's name to construct it.
>
> This is particularly painful if you have code that already uses a
> default constructor name. You may want to change the struct's
> representation, but now you can't emulate the old constructor. I guess
> the forward looking programmer would always use the make-xxx convention
> to avoid this pitfall. Am I missing anything?
>
> --
> Anthony Carrico
>
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