Re: User-defined record types

[Lars Brinkhoff]

Stefan Monnier wrote:
>> Yes, at first I tried to make cl-deftype do this by default.  But I
>> ran into problems in cl-preloaded.el and cl-generic.el.
> I can help with that.

Thanks.  I got past that and made it through to a dumped emacs which
uses record types for defstruct by default.

However, there is still EIEIO which may well need some expert guidance
to update.

> As mentioned, ideally, we'd want to store the class object directly in
> the slot 0.  The downside is that prin1 would then dump the class object
> as well, so when reading dumped objects we'd end up creating another
> copy of the class object rather than reusing an existing class object.
> And this will break cl-generic dispatch which compares class objects
> with `eq`.

Understood.  I'll look into storing the class object in slot 0.  I
imagine there will be some circular bootstrapping problem, e.g. creating
the first record object requires a class object which is a record
object.

Some suggestions:

- type-of looks into the class object and returns the symbol naming the
  class.

- class-of could be introduced to return a class object, like CLOS.

- The read/print syntax for records uses the symbol for the type slot.
  Reading a record would then maybe only work right if the class object
  has been defined first.  Not sure if that's ok.