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digitalmars.D.learn - variable declaration question

reply Traveler Hauptman <th barrett.com> writes:
Sorry if I didn't read enough for this question...

Why are class declarations redundant?

Foo a = new Foo(2,3);

Why not

Foo a(2,3) = new;

Or

new Foo a(2,3),b(22,33);
Sep 20 2005
next sibling parent Chris Sauls <ibisbasenji gmail.com> writes:
Traveler Hauptman wrote:

 Sorry if I didn't read enough for this question...
 
 Why are class declarations redundant?
 
 Foo a = new Foo(2,3);
 
 Why not
 
 Foo a(2,3) = new;
 
 Or
 
 new Foo a(2,3),b(22,33);
 


Well, one (cheap/obvious) reason is this: you can declare an Object variable
without 
creating an instance right away, so combining the decleration and instantiation
syntaxes 
is unneccessary and possibly troublesome.  Another (equally cheap/obvious)
reason is that 
you can instantiate an Object outside of a decleration, such as passing a
fully-formed 
dummy object to a function, or assigning later to an array or whatnot.  So in
short, a 
line like:



Is /three/ things happening, any of which can happen with full independance. 
One, the 
decleration of a variable of type Object.  Two, the instantiation of an object
of class 
Object.  Three, the assignment of a referance to an object to an Object
variable.

-- Chris Sauls
Sep 20 2005
prev sibling parent reply "Ben Hinkle" <bhinkle mathworks.com> writes:
"Traveler Hauptman" <th barrett.com> wrote in message 
news:dgptqk$1tha$1 digitaldaemon.com...

 Sorry if I didn't read enough for this question...

 Why are class declarations redundant?

 Foo a = new Foo(2,3);

 Why not

 Foo a(2,3) = new;

 Or

 new Foo a(2,3),b(22,33);


There have been threads on this before so you can check the archives for 
pros and cons of various ideas. My own personal favorite (outlined in 
http://www.digitalmars.com/drn-bin/wwwnews?digitalmars.D/28198) is := for 
declare and init.

On an off-D-topic, I've added := to TinyCC together with some other C 
experiments I've been wanted to try out (in particular I've been wondering 
about having to choose between Box, templates and Objects when trying to 
write generic code so I'm experimenting with fat-pointers as an 
alternative). See http://www.cxlang.org or the Google group 
http://groups.google.com/group/CXlang for what little info I put up so far. 
I haven't packaged up the compiler yet since I want to get dynamic 
dispatching working first so right now all that is available are some random 
thoughts on various goals.
Sep 21 2005
parent reply James Dunne <james.jdunne gmail.com> writes:
Ben Hinkle wrote:

 "Traveler Hauptman" <th barrett.com> wrote in message 
 news:dgptqk$1tha$1 digitaldaemon.com...
 

Sorry if I didn't read enough for this question...

Why are class declarations redundant?

Foo a = new Foo(2,3);

Why not

Foo a(2,3) = new;

Or

new Foo a(2,3),b(22,33);


 
 
 There have been threads on this before so you can check the archives for 
 pros and cons of various ideas. My own personal favorite (outlined in 
 http://www.digitalmars.com/drn-bin/wwwnews?digitalmars.D/28198) is := for 
 declare and init.
 
 On an off-D-topic, I've added := to TinyCC together with some other C 
 experiments I've been wanted to try out (in particular I've been wondering 
 about having to choose between Box, templates and Objects when trying to 
 write generic code so I'm experimenting with fat-pointers as an 
 alternative). See http://www.cxlang.org or the Google group 
 http://groups.google.com/group/CXlang for what little info I put up so far. 
 I haven't packaged up the compiler yet since I want to get dynamic 
 dispatching working first so right now all that is available are some random 
 thoughts on various goals. 
 
 


Sounds very cool.  Try to get some support for synchronization and 
threads into the language!

Could you clarify what exactly you mean by dynamic dispatching?  As I 
understand it, you can define any C function to extend a Cx "class"? 

  Am I asking too many questions?

TinyCC is awesome.  I was experimenting with that a couple months ago. 
I hacked around with it and added the ~ operator to the C language.  The 
only thing that put me off of TinyCC at the time (for any serious 
language fork development) was the lack of support for Windows 
compilation.  I believe, in the latest version, there is Windows support.
Sep 21 2005
parent "Ben Hinkle" <ben.hinkle gmail.com> writes:
 Sounds very cool.  Try to get some support for synchronization and threads 
 into the language!


ok - though don't hold your breath. I'm still just poking around.


 Could you clarify what exactly you mean by dynamic dispatching?


Just the generic sense of run-time binding: 
http://en.wikipedia.org/wiki/Dynamic_dispatch


 As I understand it, you can define any C function to extend a Cx "class"?


Well - I think of it as being able to add methods that aren't mentioned in 
the class definition. That is, the set of methods of a data type aren't 
defined by the type author. The type author only defines the methods that 
have knowledge of the internal implementation of the type. But the complete 
set of methods is known at link-time or run-time.



 Am I asking too many questions?



to declare them in the class file so that's just postponing the 
implementation of the method to somewhere else. What I'm after is adding to 
a type methods that the original type author had no idea existed.


 TinyCC is awesome.  I was experimenting with that a couple months ago. I 
 hacked around with it and added the ~ operator to the C language.  The 
 only thing that put me off of TinyCC at the time (for any serious language 
 fork development) was the lack of support for Windows compilation.  I 
 believe, in the latest version, there is Windows support.


The Windows version works great under mingw. That's the environment I've 
been using. The tcc code is a little ... hard to follow but it's amazing how 
small the whole project is. This one 9000 line file contains the 
preprocessor, compiler and linker.
Sep 21 2005