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RE: [XP] Re: Polymorphism

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  • Charlie Poole
    Ben, ... Notice that Brian subtly implies what you have just said - well it s less subtle since I capitalized the key word. ;0 ... That *is* normal
    Message 1 of 100 , Jul 31, 2002

      > On Wednesday, July 31, 2002, at 06:21 AM, Bryan Dollery wrote:
      > > So to is a base-class necessary for polymorphism, not a requirement of
      > > smalltalk, but a requirement for useful utilisation of the technique.
      > > The
      > > base-class may just be a concept in the developers head - a semantic
      > > category for classes that will be treated polymophically - but it's
      > > still a
      > > necessary prerequisite for polymorphism, because without it you code
      > > nothing but sh1te - and that's totally useless.
      > >
      > > So, technically, smalltalk supports polymorphism without a base-class,
      > > but
      > > if you want to write anything useful you need the CONCEPT of a
      > > base-class.
      > For most situations, I think that I'd agree with you. For any set of
      > methods you want to call, it seems to me you could say, these objects
      > are really This Kind Of Object, and write an interface declaration to
      > say so. I'm not sure that means that the language should require you to
      > write the declaration, if for no other reason than that there are some
      > useful things you can do without it.

      Notice that Brian subtly implies what you have just said - well it's
      less subtle since I capitalized the key word. ;0

      > Stubbing library objects for testing, for example, is easy when you
      > don't have to declare an interface.
      > Ruby's Win32OLE and RubyCocoa libraries use the ability of any Ruby
      > object to respond to a message to interoperate with other environments.
      > They respond to the fact that an appropriate method was missing from the
      > object, and forward the request on to the other environment. (IIRC,
      > Cocoa's distributed objects work this way as well.)
      > Now, in normal programming, maybe this is propeller-beanie stuff. But I
      > think that I like having it available in the language.

      That *is* normal programming. :-)

      Charlie Poole
    • Kay A. Pentecost
      Hi, Jeff, Dossy, John, Brad, Everybody!! ... And a one and a two and... uh... wrong rhythm... ... Gee, Jeff, did you go to MIT??? Thanks to all for *all* the
      Message 100 of 100 , Aug 3, 2002
        Hi, Jeff, Dossy, John, Brad, Everybody!!

        > -----Original Message-----
        > From: jeffgrigg63132 [mailto:jgrigg@...]
        > Sent: Saturday, August 03, 2002 1:50 PM
        > To: extremeprogramming@yahoogroups.com
        > Subject: Re: [XP] Lambada Calculus -vs- lambda-calculus
        > Lambada-Calculus
        > (A pun on "lambda-calculus") Teaching logic thru spanish dance steps.
        > Invented by P. van der Linden .
        > (1996-08-10)
        > -- foldoc

        And a one and a two and... uh... wrong rhythm...

        > Now as for "lambda-calculus"...
        > See: http://onlinedictionary.datasegment.com/word/lambda-calculus
        > "A branch of mathematical logic developed by Alonzo Church in the
        > late 1930s and early 1940s, dealing with the application of functions
        > to their arguments." ... "Most functional programming languages are
        > equivalent to lambda-calculus [with some convenient extensions]."
        > (It's used in the LISP language, for instance.)
        > As a practical matter, it's a syntax for defining functions --
        > often "at run time."
        > It's assumed that functions have no "side effects." That is, that
        > they perform some operation on their input arguments and return a
        > complex result -- but do not change global variables or data on disk
        > as a "side effect."
        > To do this in Visual Basic, your functions would have to return
        > Collections and arrays, and many elements of those would be
        > Collections and arrays and other complext types, down to some
        > arbitrary level of nesting. This could be really confusing in Visual
        > Basic, but it can be an effective approach to handle complex
        > processing problems if done consistently, with appropriate language
        > support.
        > Historically, these concepts have been used in artificial
        > intelligence and other highly data-driven applications.

        Gee, Jeff, did you go to MIT???

        Thanks to all for *all* the answers... sorry it took me so long to respond!!

        I didn't know unemployment would be so *hectic*!!

        First installment of Kay's Excellent Adventure at the XP Workshop starts
        next week!!

        Stay tuned!


        > --- Dossy <dossy@p...> wrote:
        > > Lambada calculus is a derivative of the sensual dance made popular
        > > in Brazil but employs a deep understanding of mathematics as part
        > > of the sensual ritual.
        > > -- Dossy
        > > On 2002.08.02, jbrewer999 <jbrewer@j...> wrote:
        > > > "Kay A. Pentecost" <tranzpupy@i...> wrote:
        > > > > Now, what's lambda calculus...<ducking>
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