Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!amdcad!light!bvs
From: bvs@light.uucp (Bakul Shah)
Newsgroups: comp.lang.c++
Subject: Re: More nits to pick at...
Keywords: self-reference
Message-ID: <1989May2.192434.23371@light.uucp>
Date: 3 May 89 02:24:32 GMT
References: <190@riunite.ACA.MCC.COM> <9279@alice.UUCP> <193@riunite.ACA.MCC.COM>
Reply-To: bvs@light.UUCP (Bakul Shah)
Organization: /etc/organization
Lines: 30

In article <193@riunite.ACA.MCC.COM> rfg@riunite.UUCP (Ron Guilmette) writes:
>>How can you declare a function which can accept a pointer
>>to itself as an argument (in a type-safe manner of course)?
>>
>>	You can't in C++ or C.
>
>Well, so is anybody (other than me) concerned about this?

A small extension to C can fix this: allow *forward* declaration
of a type name.  A later full declaration will complete the
definition.

    typedef foo;             /* forward declaration of type foo */
    typedef int (*foo)(foo); /* it is a type `function (foo) returning int' */

    int
    fun(foo f)
    {
	    ...
    }

    main()
    {
	    printf("%d\n", fun(fun));
    }

Extending an existing compiler to recognize this may not be easy
though.

-- Bakul Shah <..!{ucbvax,sun,uunet}!amdcad!light!bvs>