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Re: Java vs C++

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Joshua Cranmer wrote:
> On 02/05/2011 10:38 PM, Lawrence D'Oliveiro wrote:
>> In message<4d4d8322$0$41117$e4fe514c@news.xs4all.nl>, Silvio wrote:
>>
>>> And Lew is correct: templates and genercis are completely different
>>> beasts.
>>
>> “Completely” as in “having nothing in common”? Or is this some usage of
>> “completely” that I wasn’t aware of?
>>
>> Please explain.
> 
> Templates in C++ are basically advanced macros--each invocation of a 
> template type regenerates the class, so a Foo<int> and a Foo<double> are 
> two completely different things.

That's much more than a macro could do. Templates are a language of its 
own, include syntax checks, etc. Quite unlike macros, they do not 
substitute text patterns. Templates allow meta-programming, i.e. you can 
use the compiler to generate code. And, of course, templates are quite 
complex - very unlike the simple-minded preprocessor.

> Generics in Java are basically compile-time syntactic sugar to ensure 
> type-safety of container types at compile time instead of waiting until 
> you hit the code at runtime to get that dreaded ClassCastException.

Well, java had to take the route of type-erasure to allow generic 
progamming plus type checks because it wasn't part of the language to 
begin with, so it was "hacked" into the specs more or less. Generics are 
considerably less powerful, but also considerably easier than C++ 
templates. There's no metaprogramming with generics, and generics are 
mostly limited to containers which does not hold for C++ templates. They 
are quite different.

> About the only thing they share in common is the syntax, and even then, 
> C++ didn't allow A<B<C>> until C++0x (which, according to Bjarne 
> Stroustroup, took a bit of work to convince compiler vendors to accept).

I beg your pardon? C++ allows nested templates since C++99 and before. 
The only issue here is a notational one, namely that you had to write 
A<B<C> > (note the space behind B<C>) to avoid >> being parsed as a 
token (shifting, namely). That is the only thing that got fixed in 
C++0x, not nesting templates which is part of the language since C++99.

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Re: Java vs C++ Silvio <silvio@moc.com> - 2011-02-05 18:04 +0100
  Re: Java vs C++ Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2011-02-07 16:21 +0800
  Re: Java vs C++ Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-02-07 12:28 +1300
  Re: Java vs C++ Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-02-08 09:22 +1300
    Re: Java vs C++ Joshua Cranmer <Pidgeot18@verizon.invalid> - 2011-02-07 17:25 -0500
      Re: Java vs C++ Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-02-08 16:08 +1300
  Re: Java vs C++ Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-02-07 12:24 +1300
    Re: Java vs C++ Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-02-07 15:03 +1300
      Re: Java vs C++ Joshua Cranmer <Pidgeot18@verizon.invalid> - 2011-02-06 21:18 -0500
    Re: Java vs C++ Arne Vajhøj <arne@vajhoej.dk> - 2011-02-06 20:15 -0500
  Re: Java vs C++ Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-02-07 15:55 +1300
  Re: Java vs C++ "javax.swing.JSnarker" <gharriman@boojum.mit.edu> - 2011-02-06 19:54 -0500
  Re: Java vs C++ Arne Vajhøj <arne@vajhoej.dk> - 2011-02-06 20:50 -0500
  Re: Java vs C++ Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2011-02-07 15:54 +0800
  Re: Java vs C++ Thomas Richter <thor@math.tu-berlin.de> - 2011-02-07 01:04 +0100
    Re: Java vs C++ Arne Vajhøj <arne@vajhoej.dk> - 2011-02-06 20:26 -0500
      Re: Java vs C++ Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-02-07 19:09 +1300
        Re: Java vs C++ Lew <noone@lewscanon.com> - 2011-02-07 07:29 -0500
        Re: Java vs C++ "Mike Schilling" <mscottschilling@hotmail.com> - 2011-02-06 22:52 -0800
  Re: Java vs C++ Thomas Richter <thor@math.tu-berlin.de> - 2011-02-06 16:35 +0100
    Re: Java vs C++ Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-02-07 15:51 +1300
      Re: Java vs C++ Arne Vajhøj <arne@vajhoej.dk> - 2011-02-06 22:06 -0500
    Re: Java vs C++ Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-02-07 15:01 +1300
      Re: Java vs C++ Thomas Richter <thor@math.tu-berlin.de> - 2011-02-07 14:53 +0100
    Re: Java vs C++ Arne Vajhøj <arne@vajhoej.dk> - 2011-02-07 19:52 -0500
    Re: Java vs C++ Lew <noone@lewscanon.com> - 2011-02-06 13:09 -0500
      Re: Java vs C++ Thomas Richter <thor@math.tu-berlin.de> - 2011-02-07 00:55 +0100
    Re: Java vs C++ Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-02-07 15:00 +1300
      Re: Java vs C++ Joshua Cranmer <Pidgeot18@verizon.invalid> - 2011-02-06 21:20 -0500
        Re: Java vs C++ Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-02-07 15:52 +1300
      Re: Java vs C++ Arne Vajhøj <arne@vajhoej.dk> - 2011-02-06 21:25 -0500
    Re: Java vs C++ Arne Vajhøj <arne@vajhoej.dk> - 2011-02-06 20:29 -0500
    Re: Java vs C++ Thomas Richter <thor@math.tu-berlin.de> - 2011-02-07 00:57 +0100
    Re: Java vs C++ Joshua Cranmer <Pidgeot18@verizon.invalid> - 2011-02-06 12:57 -0500
    Re: Java vs C++ Arne Vajhøj <arne@vajhoej.dk> - 2011-02-06 15:22 -0500
    Re: Java vs C++ "Mike Schilling" <mscottschilling@hotmail.com> - 2011-02-06 08:11 -0800
    Re: Java vs C++ Ken Wesson <kwesson@gmail.com> - 2011-02-07 04:41 +0100
  Re: Java vs C++ Joshua Cranmer <Pidgeot18@verizon.invalid> - 2011-02-06 21:12 -0500
  Re: Java vs C++ Lawrence D'Oliveiro <ldo@geek-central.gen.new_zealand> - 2011-02-07 12:26 +1300
  Re: Java vs C++ Arne Vajhøj <arne@vajhoej.dk> - 2011-02-06 15:27 -0500
  Re: Java vs C++ Thomas Richter <thor@math.tu-berlin.de> - 2011-02-06 16:45 +0100
  Re: Java vs C++ Arne Vajhøj <arne@vajhoej.dk> - 2011-02-06 20:51 -0500

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