• "ixid" <nuaccount gmail.com> May 07 2012
• "bearophile" <bearophileHUGS lycos.com> May 07 2012
• "ixid" <nuaccount gmail.com> May 07 2012
• "Chris Cain" <clcain uncg.edu> May 07 2012
• "Era Scarecrow" <rtcvb32 yahoo.com> May 09 2012

"ixid" <nuaccount gmail.com> writes:

Why is the new syntax so clunky?

thing myThing = new thing;

When it could be:

new thing myThing;

"bearophile" <bearophileHUGS lycos.com> writes:

ixid:

 Why is the new syntax so clunky?

 thing myThing = new thing;

 When it could be:

 new thing myThing;


Sometimes you want to write:

class Foo {}
class Bar : Foo {}
void main() {
    Foo b = new Bar;
}

Otherwise there is 'auto' too:

auto myThing = new thing;

Bye,
bearophile

"ixid" <nuaccount gmail.com> writes:

 class Foo {}
 class Bar : Foo {}
 void main() {
    Foo b = new Bar;
 }


Thank you, could you explain what is happening in your example? 
Bar is inheriting from Foo, what are you getting when you create 
a parent of type sub-class compared  to Bar b = new Bar; and Foo 
b = new Foo; ? Foo b = new Bar won't compile if you add members 
to Bar and access them.

"Chris Cain" <clcain uncg.edu> writes:

On Monday, 7 May 2012 at 17:52:01 UTC, ixid wrote:
 Thank you, could you explain what is happening in your example? 
 Bar is inheriting from Foo, what are you getting when you 
 create a parent of type sub-class compared  to Bar b = new Bar; 
 and Foo b = new Foo; ? Foo b = new Bar won't compile if you add 
 members to Bar and access them.


Hello,

Foo is the "interface" you'll have to bar.

So, a bit of a bigger example:


-=-=-=-
import std.stdio;
class Foo {
     void doStuff() {}
}
class Bar : Foo {
     void doStuff() {
         writeln("Hi");
     }
     void doThings() { }
}

void main() {
     Foo f = new Bar;
     f.doStuff(); // prints "Hi" to the screen
     f.doThings(); // doesn't compile
}
-=-=-=-

So, as you can see, if you have a Foo, you can't call "doThings" 
using it. However, if your Foo is actually a Bar underneath, then 
it'll use Bar's version of "doStuff".

OOP isn't terribly hard, but I suggest reading up on it some to 
grasp the concepts (and especially so you can see the benefits).

Here's a link that might help you get started on some of the 
fundamentals:
http://en.wikipedia.org/wiki/Object-oriented_programming#Fundamental_features_and_concepts

"Era Scarecrow" <rtcvb32 yahoo.com> writes:

On Monday, 7 May 2012 at 18:03:45 UTC, Chris Cain wrote:
 On Monday, 7 May 2012 at 17:52:01 UTC, ixid wrote:
 Thank you, could you explain what is happening in your  
 example? Bar is inheriting from Foo, what are you getting when 
  you create a parent of type sub-class compared  to Bar b = 
 new  Bar; and Foo b = new Foo; ? Foo b = new Bar won't compile 
 if  you add members to Bar and access them.




 Foo is the "interface" you'll have to bar.

 OOP isn't terribly hard, but I suggest reading up on it some to 
  grasp the concepts (and especially so you can see the 
 benefits).


  D also takes the approach with classes and objects that is 
closer to java than C++: All methods are overridable for 
polymorphism by default. Using interfaces and safely up&down 
casting using the known interfaces is so much easier. I haven't 
done much with C++, but these types of things are more error and 
bug prone than D and java; Not to mention the STL gives me a 
total headache.

  I have a good mental idea of how to explain OOP and inheritance 
using a RPG-like game example, which would be less confusing than 
the usual animals and shapes (At least it is to me).