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* 'head' specializer for cl-defmethod?
@ 2015-07-28 12:06 Stephen Leake
  2015-07-28 20:39 ` Dmitry Gutov
  2015-07-29  0:01 ` Stefan Monnier
  0 siblings, 2 replies; 3+ messages in thread
From: Stephen Leake @ 2015-07-28 12:06 UTC (permalink / raw)
  To: emacs-devel

project.el uses a 'head' specializer in the dispatching argument of
cl-defmethod.

This use of 'head' is not documented other than in the 'Added elements'
section of the cl-generic.el header comment.

I'd like to change the cl-defmethod doc
string to say:

    Other than a type, TYPE can also be one of the following:

    - `(eql VAL)' - this method will be invoked when the
      argument is `eql' to VAL.

    - `(head VAL)' - this method will be invoked when the `car' of the
      argument is `eql' to VAL


However, that still leaves out the eieio-core specializer `subclass';
I'm not clear how to handle that in the doc string.

I'm guessing the rationale for supporting the 'head' specializer is to
allow using cl-defmethod with objects that are constructed by `cons',
without any cl-defstruct or eieio defclass. That's how it is used in
project.el.


Is there a manual section for cl-defmethod? I don't see one in
doc/misc/cl.texi; perhaps we should add one?

--
-- Stephe



^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: 'head' specializer for cl-defmethod?
  2015-07-28 12:06 'head' specializer for cl-defmethod? Stephen Leake
@ 2015-07-28 20:39 ` Dmitry Gutov
  2015-07-29  0:01 ` Stefan Monnier
  1 sibling, 0 replies; 3+ messages in thread
From: Dmitry Gutov @ 2015-07-28 20:39 UTC (permalink / raw)
  To: Stephen Leake, emacs-devel

On 07/28/2015 03:06 PM, Stephen Leake wrote:

> This use of 'head' is not documented other than in the 'Added elements'
> section of the cl-generic.el header comment.

This statement is also probably outdated: "and all methods of NAME have 
to use the same argument for dispatch". At least I can use a dispatch on 
an argument together with dispatch on &context (which also needs to be 
documented).

> Is there a manual section for cl-defmethod? I don't see one in
> doc/misc/cl.texi; perhaps we should add one?

We should.



^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: 'head' specializer for cl-defmethod?
  2015-07-28 12:06 'head' specializer for cl-defmethod? Stephen Leake
  2015-07-28 20:39 ` Dmitry Gutov
@ 2015-07-29  0:01 ` Stefan Monnier
  1 sibling, 0 replies; 3+ messages in thread
From: Stefan Monnier @ 2015-07-29  0:01 UTC (permalink / raw)
  To: Stephen Leake; +Cc: emacs-devel

> I'd like to change the cl-defmethod doc
> string to say:

>     Other than a type, TYPE can also be one of the following:

>     - `(eql VAL)' - this method will be invoked when the
>       argument is `eql' to VAL.

>     - `(head VAL)' - this method will be invoked when the `car' of the
>       argument is `eql' to VAL

> However, that still leaves out the eieio-core specializer `subclass';
> I'm not clear how to handle that in the doc string.

Actually, the docstring should be dynamically generated (like the
one of `pcase') to show the various options, since these can be extended
by third party packages.


        Stefan



^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2015-07-29  0:01 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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2015-07-28 12:06 'head' specializer for cl-defmethod? Stephen Leake
2015-07-28 20:39 ` Dmitry Gutov
2015-07-29  0:01 ` Stefan Monnier

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