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Re: simple method to simulate function pointers in java

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In article 
<39f8a144-5eaa-4b7f-b335-efb75539ff95@glegroupsg2000goo.googlegroups.com
>,
 Lew <lewbloch@gmail.com> wrote:

> Arne Vajhøj wrote:
> > Lino Ferrentino wrote:
> >> Maybe there are other methods... I use this:
> >>
> >> [code omitted]
> >>
> >> to call the callback
> >>
> >> my_callback.f(42);
> >>
> >>
> >> For each function pointer type we create an interface.
> > 
> > It is perfectly valid.
> > 
> > You need to note two things:
> > 1) the codes is not following Java coding convention
> > 2) it is based on an assumption that all functions with
> >     the same signature are interchangeable - that is not
> >     very type safe
> 
> The Java idiom is to use a functor, typically a 
> single-abstract-method (SAM) interface, and pass an instance of that 
> functor type to the object needing a callback or similar method.  The 
> object implementing the functor interface is the called-back object.
> 
> And as Arne says, do follow the coding conventions.  Your code was 
> nearly impenetrable.  You name things by purpose in Java, not by 
> implementation type.
> 
> Roughly (very roughly)_speaking, the functor pattern is something like:
> 
>  [code omitted]

A related example of this widely used pattern may be found in 
`EventListenerList` [1], which adds a measure of type safety by
using a class literal as a runtime type-token [2].

[1]<http://download.oracle.com/javase/7/docs/api/javax/swing/event/EventListenerList.html>
[2]<http://download.oracle.com/javase/tutorial/extra/generics/literals.html>

-- 
John B. Matthews
trashgod at gmail dot com
<http://sites.google.com/site/drjohnbmatthews>

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simple method to simulate function pointers in java Lino Ferrentino <lino.ferrentino@gmail.com> - 2011-09-02 01:54 -0700
  Re: simple method to simulate function pointers in java Mayeul <mayeul.marguet@free.fr> - 2011-09-02 11:56 +0200
  Re: simple method to simulate function pointers in java Patricia Shanahan <pats@acm.org> - 2011-09-02 03:17 -0700
    Re: simple method to simulate function pointers in java Lino Ferrentino <lino.ferrentino@gmail.com> - 2011-09-02 05:11 -0700
      Re: simple method to simulate function pointers in java Arne Vajhøj <arne@vajhoej.dk> - 2011-09-05 21:21 -0400
  Re: simple method to simulate function pointers in java Roedy Green <see_website@mindprod.com.invalid> - 2011-09-02 07:43 -0700
  Re: simple method to simulate function pointers in java Arne Vajhøj <arne@vajhoej.dk> - 2011-09-05 21:24 -0400
    Re: simple method to simulate function pointers in java Lew <lewbloch@gmail.com> - 2011-09-05 19:00 -0700
      Re: simple method to simulate function pointers in java "John B. Matthews" <nospam@nospam.invalid> - 2011-09-06 13:39 -0400

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