change in call-next-method

change in call-next-method

[Stephen Leake]

I'm updating JDEE to Emacs 25. It has several functions like this:

(cl-defmethod initialize-instance ((this jdee-jddocset) &rest rest)
  (apply 'call-next-method rest)
  (unless (oref this description)
    (oset this :description
	  (if (oref this jdkp)
	      (format "JDK %s Javadoc" (oref this version))
	    (let ((file (jdee-url-file (oref this url))))
	      (if (string-match ".*\\/\\(.*?\\)\\/doc\\/api" file)
		  (match-string 1 file)
		(jdee-url-name (oref this url))))))))

This breaks if I just change call-next-method to cl-call-next-method. In
Emacs 24, `call-next-method' is a defun that does the right thing here
(calls the default superclass init). In Emacs 25, cl-call-next-method is
a defun that throws an error; cl-defmethod is supposed to replace plain
calls to cl-call-next-method with an in-line call to the appropriate
method.

As far as I can tell, the only reason for the call to call-next-method
is to process the constructor args in `rest', storing them in the
appropriate slots.

What is the right way to do that in Emacs 25? I don't see anything in
the CL manual about this, and I can't find the relevant code by reading
the implementations of cl-defmethod or cl-generic.

-- 
-- Stephe

change in call-next-method

[Stephen Leake]

I'm updating JDEE to Emacs 25. It has several functions like this:

(cl-defmethod initialize-instance ((this jdee-jddocset) &rest rest)
  (apply 'call-next-method rest)
  (unless (oref this description)
    (oset this :description
	  (if (oref this jdkp)
	      (format "JDK %s Javadoc" (oref this version))
	    (let ((file (jdee-url-file (oref this url))))
	      (if (string-match ".*\\/\\(.*?\\)\\/doc\\/api" file)
		  (match-string 1 file)
		(jdee-url-name (oref this url))))))))

This breaks if I just change call-next-method to cl-call-next-method. In
Emacs 24, `call-next-method' is a defun that does the right thing here
(calls the default superclass init). In Emacs 25, cl-call-next-method is
a defun that throws an error; cl-defmethod is supposed to replace plain
calls to cl-call-next-method with an in-line call to the appropriate
method.

As far as I can tell, the only reason for the call to call-next-method
is to process the constructor args in `rest', storing them in the
appropriate slots.

What is the right way to do that in Emacs 25? I don't see anything in
the CL manual about this, and I can't find the relevant code by reading
the implementations of cl-defmethod or cl-generic.

--
-- Stephe

Re: change in call-next-method

[Andreas Schwab]

Stephen Leake <stephen_leake@stephe-leake.org> writes:

> I'm updating JDEE to Emacs 25. It has several functions like this:
>
> (cl-defmethod initialize-instance ((this jdee-jddocset) &rest rest)
>   (apply 'call-next-method rest)
>   (unless (oref this description)
>     (oset this :description
> 	  (if (oref this jdkp)
> 	      (format "JDK %s Javadoc" (oref this version))
> 	    (let ((file (jdee-url-file (oref this url))))
> 	      (if (string-match ".*\\/\\(.*?\\)\\/doc\\/api" file)
> 		  (match-string 1 file)
> 		(jdee-url-name (oref this url))))))))
>
> This breaks if I just change call-next-method to cl-call-next-method.

How do you change it?  I think you are supposed to call it as
(cl-call-next-method).

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: change in call-next-method

[Stephen Leake]

Andreas Schwab <schwab@linux-m68k.org> writes:

> Stephen Leake <stephen_leake@stephe-leake.org> writes:
>
>> I'm updating JDEE to Emacs 25. It has several functions like this:
>>
>> (cl-defmethod initialize-instance ((this jdee-jddocset) &rest rest)
>>   (apply 'call-next-method rest)
>>   (unless (oref this description)
>>     (oset this :description
>> 	  (if (oref this jdkp)
>> 	      (format "JDK %s Javadoc" (oref this version))
>> 	    (let ((file (jdee-url-file (oref this url))))
>> 	      (if (string-match ".*\\/\\(.*?\\)\\/doc\\/api" file)
>> 		  (match-string 1 file)
>> 		(jdee-url-name (oref this url))))))))
>>
>> This breaks if I just change call-next-method to cl-call-next-method.
>
> How do you change it?  

I tried:

(apply 'cl-call-next-method rest)
(cl-call-next-method rest)

They both give the error:

cl-call-next-method: cl-call-next-method only allowed inside primary and around methods

> I think you are supposed to call it as
> (cl-call-next-method).

That gives the same error.

Note that I don't actually need to call the superclass init; I just need
to process the args in `rest', storing them in the slots.

I can write code that does it:

  (let ((description (plist-get rest :description))
        (url (plist-get rest :url))
        (jdkp (plist-get rest :jdkp))
        (version (plist-get rest :version)))
    (when description
      (oset this :description description))
    (when url
      (oset this :url url))
    (when jdkp
      (oset this :jdkp jdkp))
    (when version
      (oset this :version version)))

but that's tedious and error-prone.

-- 
-- Stephe

Re: change in call-next-method

[Eric Abrahamsen]

Stephen Leake <stephen_leake@stephe-leake.org> writes:

> Andreas Schwab <schwab@linux-m68k.org> writes:
>
>> Stephen Leake <stephen_leake@stephe-leake.org> writes:
>>
>>> I'm updating JDEE to Emacs 25. It has several functions like this:
>>>
>>> (cl-defmethod initialize-instance ((this jdee-jddocset) &rest rest)
>>>   (apply 'call-next-method rest)
>>>   (unless (oref this description)
>>>     (oset this :description
>>> 	  (if (oref this jdkp)
>>> 	      (format "JDK %s Javadoc" (oref this version))
>>> 	    (let ((file (jdee-url-file (oref this url))))
>>> 	      (if (string-match ".*\\/\\(.*?\\)\\/doc\\/api" file)
>>> 		  (match-string 1 file)
>>> 		(jdee-url-name (oref this url))))))))
>>>
>>> This breaks if I just change call-next-method to cl-call-next-method.
>>
>> How do you change it?  
>
> I tried:
>
> (apply 'cl-call-next-method rest)
> (cl-call-next-method rest)
>
> They both give the error:
>
> cl-call-next-method: cl-call-next-method only allowed inside primary and around methods
>
>> I think you are supposed to call it as
>> (cl-call-next-method).
>
> That gives the same error.
>
> Note that I don't actually need to call the superclass init; I just need
> to process the args in `rest', storing them in the slots.

I think if you replace any of the args, you need to replace *all* of the
args. Ie, either:

(cl-call-next-method) ; in which case your changes to REST are ignored

or

(cl-call-next-method this rest)

Otherwise, it's just the wrong number of arguments.

I may be missing something, but...

Re: change in call-next-method

[Stephen Leake]

Eric Abrahamsen <eric@ericabrahamsen.net> writes:

> Stephen Leake <stephen_leake@stephe-leake.org> writes:
>
>> Andreas Schwab <schwab@linux-m68k.org> writes:
>>
>>> Stephen Leake <stephen_leake@stephe-leake.org> writes:
>>>
>>>> I'm updating JDEE to Emacs 25. It has several functions like this:
>>>>
>>>> (cl-defmethod initialize-instance ((this jdee-jddocset) &rest rest)
>>>>   (apply 'call-next-method rest)
>>>>   (unless (oref this description)
>>>>     (oset this :description
>>>> 	  (if (oref this jdkp)
>>>> 	      (format "JDK %s Javadoc" (oref this version))
>>>> 	    (let ((file (jdee-url-file (oref this url))))
>>>> 	      (if (string-match ".*\\/\\(.*?\\)\\/doc\\/api" file)
>>>> 		  (match-string 1 file)
>>>> 		(jdee-url-name (oref this url))))))))
>>>>
>>>> This breaks if I just change call-next-method to cl-call-next-method.
>>>
>>> How do you change it?  
>>
>> I tried:
>>
>> (apply 'cl-call-next-method rest)
>> (cl-call-next-method rest)
>>
>> They both give the error:
>>
>> cl-call-next-method: cl-call-next-method only allowed inside primary and around methods
>>
>>> I think you are supposed to call it as
>>> (cl-call-next-method).
>>
>> That gives the same error.
>>
>> Note that I don't actually need to call the superclass init; I just need
>> to process the args in `rest', storing them in the slots.
>
> I think if you replace any of the args, you need to replace *all* of the
> args. Ie, either:
>
> (cl-call-next-method) ; in which case your changes to REST are ignored
>
> or
>
> (cl-call-next-method this rest)
>
> Otherwise, it's just the wrong number of arguments.

Same error.

> I may be missing something, but...

I think this error is due to trying to call the parent method, when
there isn't one:

(defclass jdee-jddocset ()
<slots>...
 )
 
In Emacs 24.5, that calls the default superclass method. Apparently that
call doesn't work properly in Emacs 25.

There is an initialize-instance defined for the default superclass; in
eieio.el:

(cl-defmethod initialize-instance ((this eieio-default-superclass)
				&optional slots)
  "Construct the new object THIS based on SLOTS.
SLOTS is a tagged list where odd numbered elements are tags, and
even numbered elements are the values to store in the tagged slot.
If you overload the `initialize-instance', there you will need to
call `shared-initialize' yourself, or you can call `call-next-method'
to have this constructor called automatically.  If these steps are
not taken, then new objects of your class will not have their values
dynamically set from SLOTS."
  ;; First, see if any of our defaults are `lambda', and
  ;; re-evaluate them and apply the value to our slots.
  (let* ((this-class (eieio--object-class this))
         (slots (eieio--class-slots this-class)))
    (dotimes (i (length slots))
      ;; For each slot, see if we need to evaluate it.
      ;;
      ;; Paul Landes said in an email:
      ;; > CL evaluates it if it can, and otherwise, leaves it as
      ;; > the quoted thing as you already have.  This is by the
      ;; > Sonya E. Keene book and other things I've look at on the
      ;; > web.
      (let* ((slot (aref slots i))
             (initform (cl--slot-descriptor-initform slot))
             (dflt (eieio-default-eval-maybe initform)))
        (when (not (eq dflt initform))
          ;; FIXME: We should be able to just do (aset this (+ i <cst>) dflt)!
          (eieio-oset this (cl--slot-descriptor-name slot) dflt)))))
  ;; Shared initialize will parse our slots for us.
  (shared-initialize this slots))

That seems to be the code I'm looking for. Maybe with this clue I can
figure out why the call fails.

-- 
-- Stephe

Re: change in call-next-method

[Stephen Leake]

Stephen Leake <stephen_leake@stephe-leake.org> writes:

> Andreas Schwab <schwab@linux-m68k.org> writes:
>
>> Stephen Leake <stephen_leake@stephe-leake.org> writes:
>>
>>> I'm updating JDEE to Emacs 25. It has several functions like this:
>>>
>>> (cl-defmethod initialize-instance ((this jdee-jddocset) &rest rest)
>>>   (apply 'call-next-method rest)
>>>   (unless (oref this description)
>>>     (oset this :description
>>> 	  (if (oref this jdkp)
>>> 	      (format "JDK %s Javadoc" (oref this version))
>>> 	    (let ((file (jdee-url-file (oref this url))))
>>> 	      (if (string-match ".*\\/\\(.*?\\)\\/doc\\/api" file)
>>> 		  (match-string 1 file)
>>> 		(jdee-url-name (oref this url))))))))
>>>
>>> This breaks if I just change call-next-method to cl-call-next-method.
>>
>> How do you change it?  
>
> I tried:
>
> (apply 'cl-call-next-method rest)
> (cl-call-next-method rest)
>
> They both give the error:
>
> cl-call-next-method: cl-call-next-method only allowed inside primary and around methods
>
>> I think you are supposed to call it as
>> (cl-call-next-method).
>
> That gives the same error.

I take it back. In my simplified test code, I was using "defmethod"
instead of "cl-defmethod". Fixing that, and using your suggestion, fixes
the original problem.

Thanks.

-- 
-- Stephe