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From: calder@uluru.stanford.edu (Paul Calder)
Newsgroups: comp.windows.interviews
Subject: Re: PushButton for 3.0
Message-ID: <CALDER.91May8100706@uluru.stanford.edu>
Date: 8 May 91 14:07:06 GMT
References: <"<9105061205.AA09569@cnmus.cnm.us.es>
Sender: news@leland.Stanford.EDU (Mr News)
Reply-To: calder@lurch.stanford.edu
Organization: Stanford University
Lines: 33
In-Reply-To: juando@cnm.us.es's message of 6 May 91 13:05:55 GMT

Juan has a good question about building PushButtons from glyphs ...

    The telltale for the Button would be built inside this constructor,
    however, Button parent class requires the telltale before I can build it.

Here are two suggestions; I prefer the first.

1. PushButton needn't be derived from Button.  Just make it a MonoGlyph.

    PushButton::PushButton (...) : MonoGlyph(nil) {
        Telltale* t  = ...;
        Button* b = new Button(..., t, );
        body(b)
    }

2. Use a helper function to build the Telltale.

    static Telltale* make_telltale (...) {
        Telltale* t = ...;
        return t;
    }

    PushButton::PushButton (
        ...
    ) : Button(..., make_telltale(...), ...) {
        ...
    }

--
Paul Calder
Computer Systems Lab
Stanford University
calder@lurch.stanford.edu