cl-generic.el: lexical-let patch for method dispatch lambdas #27
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This patch serves to ensure that the following code will complete
without error, returning an expected value from the 'frob' method
specialized on the class 'b'
~~~~
(require 'eieio)
(defclass a ()
())
(defclass b (a)
())
(cl-defgeneric frob (obj)
(:method ((obj a))
(list :a obj))
(:method ((obj b))
(append (when (cl-next-method-p)
(cl-call-next-method))
(list :b))))
(frob (b))
;; => (:a #s(b) :b)
~~~~
Previously, there were unbound symbols in anonymous lambda forms
initialized for dispatch in the method call.
An excerpt from the backtrace on the method call for `(frob (b))` with
the unpatched source:
~~~~
(apply #'(lambda (cl--nmp cl--cnm obj) (progn (append (if (funcall cl--nmp) (progn (funcall cl--cnm))) (list :b)))) cl--nmp cl--cnm cl--args)
(let ((cl--cnm #'(lambda (&rest args) (apply cl--nm (or args cl--args))))) (apply #'(lambda (cl--nmp cl--cnm obj) (progn (append (if (funcall cl--nmp) (progn ...)) (list :b)))) cl--nmp cl--cnm cl--args))
(lambda (&rest cl--args) "\n\n(fn OBJ)" (let ((cl--cnm #'(lambda (&rest args) (apply cl--nm ...)))) (apply #'(lambda (cl--nmp cl--cnm obj) (progn (append ... ...))) cl--nmp cl--cnm cl--args)))(#<b b-2083ca3bc>)
apply((lambda (&rest cl--args) "\n\n(fn OBJ)" (let ((cl--cnm #'(lambda (&rest args) (apply cl--nm ...)))) (apply #'(lambda (cl--nmp cl--cnm obj) (progn (append ... ...))) cl--nmp cl--cnm cl--args))) #<b b-2083ca3bc> nil)
frob(#<b b-2083ca3bc>)
~~~~
This patch establishes a lexical binding for variables that must be
accessible in some encapsulated lambda form in the initial method
call.
This patch has been tested with GNU Emacs 29.0.50 built from the
FreeBSD port editors/emacs-devel version 29.0.50.20220515,2 with
the NATIVECOMP option enabled in the Emacs build.
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This pull request should have been created from a patch branch singularly for this changeset: cl-generic.el: lexical-let patch for method dispatch lambdas Albeit already having published this pull request, I've created a patch branch for this, in the local contrib fork: ci/patch/cl-generic-lexical-let. This would have been the origin branch from which to have created the initial pull request. The latter branch will be updated with changesets only for this patch set. I've converted this initial pull request to a draft, understanding that any later additions to the 'thinkum' branch in my contrib fork would be automatically appended to this initial pull request. I'm not seeing any 'delete pull request' option here at GitHub. I'll try to send the patch along with a reference to the diff here at GitHub, using |
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Pursuant towards developing a complete patch for this and sending a pull request from a patch branch singularly for that patch set, I've closed this pull request. With the patch as contributed in that first changeset -- as referred above -- I'd tested the patch with the updated cl-generic.el evaluated from source. When building emacs with the patched file, the build failed Of course, I see now that |
This patch serves to ensure that the following code will complete without error, returning an expected value from the 'frob' method specialized on the class 'b'
Originally, there were unbound symbols in anonymous lambda forms initialized for dispatch in the method call.
An excerpt from the backtrace on the method call for
(frob (b))with the unpatched source:This patch establishes a lexical binding for variables that must be accessible in some encapsulated lambda form in the initial method call -- with a shoutout to the Emacs Wiki, for an introduction to Emacs
lexical-letThis patch has been tested with GNU Emacs 29.0.50 built from the FreeBSD port editors/emacs-devel version 29.0.50.20220515,2 with the NATIVECOMP option enabled in the Emacs build.
System information from
report-emacs-bug: