[Grace-core] Blog fodder

[Kim Bruce]

Somehow I didn't get a chance to look at this page earlier.  I tentatively agree with most of the comments on parameterization.  A few points:

1.  class declarations as first class values.  While I also had them as first class values in my book, I'd like to discuss this in the context of my concerns from a week plus ago about object definitions being generative.  It comes down to whether object and class definitions should be declarations or regular expressions.

2.  I'm a bit surprised to see you write self.type in example 3.  While part of me would love to include a mytype style type in the language, it has some consequences for typing.  We should discuss this.  [Let me know if I am misunderstanding that notation.]

3.  The more I think about automagically having class names overloaded with type names (e.g., Complex in your examples), the more nervous I get about it.  I'd rather see us require the type definition to be given before the class definition and then use that name in the class definition.

E.g.
type Complex{
        method real-> Number
        method imag -> Number 
        method + other:self.type -> self.type 
        method - other:self.type -> self.type
        method abs -> Number
        method conj -> self.type
}

const ComplexCartesian := class { re:Number , im:Number ->
        const real:Number := re
        const imag:Number := im
        method + other:self.type -> self.type {
            ComplexCartesian.new(real + other.real , imag + other.imag) }
        method - other:self.type -> self.type {
            ComplexCartesian.new(real - other.real , imag - other.imag) }
        method abs -> Number {
            (real.squared + imag.squared).sqrt } }
        method conj -> self.type {
            real - imag.i }

const myComplex: Complex := ComplexCartesian.new(9,3)

[Of course I notice that you used self.type instead of Complex here, but I'd put Complex in its place if we are not going to use that construct.]

Kim



On Apr 27, 2011, at 8:38 AM, Andrew P. Black wrote:

> I wrote this page before I left Cambridge
> 
> https://projects.cecs.pdx.edu:8443/~black/NewOOL/index.cgi/wiki/DeclaringThingsWithParameters
> 
> There are no comments there.  I think that, as it is written, it would make an excellent blog post.
> 
> 	Andrew
> 
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