[Openmcl-devel] defstruct - generic constructor?

Dan Weinreb dlw at itasoftware.com
Wed Apr 29 20:56:19 UTC 2009


This behavior isn't specific to CCL; it's part of the definition
of Common Lisp.  If you want to use make-instance, you
should use defclass instead of defstruct.  (defstruct is an
earlier, more primitive facility that was added to Lisp
before object-oriented programming.)

David Reitter wrote:
> I've been trying to make instances of objects whose types have been  
> defined using `defstruct'.
>
> Unfortunately, the obvious `make-instance' doesn't work (with ccl at  
> least).  I'm glad, however, that `class-of' and `class-name' do their  
> jobs.
>
> The only way I got this to work was this clumsy hack:
>
> (apply (read-from-string (format nil "make-~a" (class-name chunk-type)))
> ...)
>
> Is there a nicer, more efficient way of doing this?
> I'd need to find out what the constructor is for a given class.   
> Reading the `defstruct'  code didn't help me much.
>
> In more general terms, can I expect that `class-of' and `class-name'  
> work for structures in other CL implementations?
>
> Thanks for your input.
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>   



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