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Re: [Emacs-diffs] trunk r116995: cl-lib defstruct introspection
From: |
Stefan Monnier |
Subject: |
Re: [Emacs-diffs] trunk r116995: cl-lib defstruct introspection |
Date: |
Mon, 21 Apr 2014 23:28:09 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.4.50 (gnu/linux) |
> Something like this. (This is the private code I was talking about, so
> it doesn't use the sames in the checked-in patch.)
> (defmacro* jez-with-slots (spec-list (type inst) &body body)
> "Like `with-slots', but for structs."
> (if (symbolp inst)
> `(symbol-macrolet
> ,(loop for spec in spec-list
> collect `(,spec (jez-slot-value ',type ,inst ',spec)))
> ,@body)
> (let ((inst-symbol (gensym "with-struct-slots")))
> `(let ((,inst-symbol ,inst))
> (jez-with-slots
> ,spec-list ,inst-symbol ,@body)))))
Ah, I see now, thanks, yes that makes sense.
Stefan
PS: Of course, I wouldn't implement it that way ;-)
I'd start by testing `inst' against `type' and then use straight (aref
...) or (nth ...) for the accessors.
But indeed, you'd want to circumvent the usual accessors.