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I completely agree with you. I think Microsoft was so much inspired by the Java while developing C#, there are some differences but on the core they are both same…
cout << "\0";
// its backSlashZero
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C# isn't perfect, but at least it's not Java.
“Time and space can be a bitch.”
–Gushie, Quantum Leap
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2a) is a good thing--it allows you to bypass the type system for some nifty tricks (generics can't do everything).
2b) I agree with, I wish C# had M.I.
I'd forgotten Java has G.C., it's been so long since I've used it. But personally I hate GC--that's the single biggest mistake the C# designers made. IMO
Logan
“Time and space can be a bitch.”
–Gushie, Quantum Leap
{o,o}.oO( Looking for a great RSS reader? Try FeedBeast! )
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2a) isn't a good thing. Generics are bad. Templates are a lot better.
To those who understand, I extend my hand.
To the doubtful I demand: Take me as I am.
Not under your command, I know where I stand.
I won't change to fit yout plan. Take me as I am.
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I don't recall much difference between generics and templates. Am I totally missing something?
“Time and space can be a bitch.”
–Gushie, Quantum Leap
{o,o}.oO( Looking for a great RSS reader? Try FeedBeast! )
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There is a BIG difference between templates and generics.
Templates works like this:
0. Programmer writes generic function/class/whatever. Example:
// this is C++
// compiler won't generate any code from this
template <class T>
class CLinkedList
{
private:
T m_tValue;
CLinkedList<T> *m_plltNext;
public:
//...
};
1. At compile time, whenever the compiler finds an instance of the template, the program replaces all instances of the template parameters with its actual values. Example:
int main()
{
// compiler will create a class called CLinkedList<int>
CLinkedList<int> lliExample;
// compiler will create ANOTHER class called CLinkedList<double>
CLinkedList<double> lldAnotehrExample;
return 0;
}
2. At run time, the program doesn't know ANYTHING about the templates. It only knows about its specific instances (the actual functions/classes/whatever).
Generics work like this:
0. Programmer writes generic function
' this is VB.NET
' in .NET, generic classes have metadata that tell the runtime that they have parameters.
Public Class LinkedList(Of T)
Private Value As T
Private NextNode As LinkedList(Of T) ' the implicit pointer... yuck!
' ...
End Class
1. At compile time, the compiler doesn't create new classes from the generic definition.
Module Test
' I don't remember very well, but I think the VB.NET equivalent of static is Shared
Public Shared Sub Main()
' compiler will generate code that tells the runtime to replace
' the generic metadata with the actual generic parameters
Dim LLOfInt As LinkedList(Of Integer), LLOfDouble As LinkedList(Of Double)
End Sub
End Module
2. At run time, the JIT/interpreter only knows about the generic class until it finds a request to create/use an instance of a specialization of the generic.
---
Are generics more powerful than templates? No. You can do this in C++:
template <class T>
class CBox
{
public:
T content;
};
int main()
{
CBox<int> a;
CBox<double> b;
a.content = 10;
b.content = 15;
b.content += a.content; // C# equivalent can't do this
}
Are generics safer? If you can't program, yes. But we're supposed to know how to program.
To those who understand, I extend my hand.
To the doubtful I demand: Take me as I am.
Not under your command, I know where I stand.
I won't change to fit yout plan. Take me as I am.
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leonej_dt wrote: CBox<int> a;
CBox<double> b;
a.content = 10;
b.content = 15;
b.content += a.content; // C# equivalent can't do this
I don't know why you say this. I just wrote the following version in C# with generics and it works perfectly:
class Box<T> {
public T content;
}
Box<int> x = new Box<int>();
Box<double> y = new Box<double>();
x.content = 10;
y.content = 15;
y.content += (double)x.content;
Yes, C# makes you cast the int to a double, but that's hardly a limitation.
“Time and space can be a bitch.”
–Gushie, Quantum Leap
{o,o}.oO( Looking for a great RSS reader? Try FeedBeast! )
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modified on Monday, April 7, 2008 12:50 PM
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And what about this?
namespace test
{
class Base { }
class Test1 : Base { void Test() { Console.WriteLine("Test performed by Test1"); } }
class Test2 : Base { void Test() { Console.WriteLine("Test performed by Test2"); } }
class Test3 : Base { }
class Box<T>
{
public T content;
}
class Program
{
static void Main(string[] args)
{
Box<Base> bb = new Box<Base>;
Random r = new Random();
int i = r.Next() % 3;
switch (i)
{
case 0:
bb.content = new Test1();
break;
case 1:
bb.content = new Test2();
break;
case 2: bb.content = new Test3();
break;
}
if (i < 2)
bb.content.Test(); // error
else
Console.WriteLine("Can't perform test.");
}
}
}
To those who understand, I extend my hand.
To the doubtful I demand: Take me as I am.
Not under your command, I know where I stand.
I won't change to fit yout plan. Take me as I am.
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I'll just take your word on that one. :P
“Time and space can be a bitch.”
–Gushie, Quantum Leap
{o,o}.oO( Looking for a great RSS reader? Try FeedBeast! )
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-”-”-
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I'm sorry, I got it TOTALLY wrong with my examples. But here's a better comparison between templates and generics:
http://blogs.msdn.com/branbray/archive/2003/11/19/51023.aspx[^]
To those who understand, I extend my hand.
To the doubtful I demand: Take me as I am.
Not under your command, I know where I stand.
I won't change to fit yout plan. Take me as I am.
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Cool! I'll check it out later, now that u've piqued my curiosity. 
Thanks
“Time and space can be a bitch.”
–Gushie, Quantum Leap
{o,o}.oO( Looking for a great RSS reader? Try FeedBeast! )
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Ahhh, so the big difference (in my mind at least) is that templates are compile-time "specialized", while generics are run-time specialized. This means that with templates and C++ you can basically treat the type parameter as whatever you want, and the compiler will tell you if you can't do it.
With generics and C#, there is no such freedom because you must specify all of your constraints up-front (since generics are specializable at runtime and therefore must be able to accept any compatible type, not just the ones you happen to use).
Now that I remember a little, I did like that about C++, and it is one thing I find particularly annoying about C#, so thanks for clarifying that for me.
Logan
“Time and space can be a bitch.”
–Gushie, Quantum Leap
{o,o}.oO( Looking for a great RSS reader? Try FeedBeast! )
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Also...
leonej_dt wrote: Private NextNode As LinkedList(Of T) ' the implicit pointer... yuck!
How is this any different from:
leonej_dt wrote: CLinkedList<t> *m_plltNext;
I don't understand your "yuck!" could you please explain that to me? Are you referring to the fact the .NET keeps a reference as opposed to a pointer, and thus keeps the object alive?
[Update: Oh I see, the C++ version isn't type-specific, so you can link together instances of different-templated LinkedLists. Hmm that's interesting, but you could still do this in C# without generics, by using a common base type or interface (or even just object).]
“Time and space can be a bitch.”
–Gushie, Quantum Leap
{o,o}.oO( Looking for a great RSS reader? Try FeedBeast! )
|)””’) Built with home-grown CodeProject components!
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One problem I do have with generics is that there is no "is a" relationship between GenericClass<SubType> and GenericClass<BaseType>.
For example, List<Button> "IS A" List<Control>, but C# doesn't accept this, to my knowledge.
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No! A List IS NOT a List<control> because a List can't contain Controls. The fact both lists could contain Buttons is just a mere coincidence.
To those who understand, I extend my hand.
To the doubtful I demand: Take me as I am.
Not under your command, I know where I stand.
I won't change to fit yout plan. Take me as I am.
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Hm, I see your point: you wouldn't want to allow a List-Button (i'm skipping the freaking angle-brackets, yeesh enough probs already) to have Controls added to it--because it should guarantee that it contains only Buttons--but it should be interpretable as a List-Control for the purpose of some method or operation that expects a List-Control.
So I guess what I mean is, the "is a" relationship should apply to read-only interpretations (casts if you will) of the original. C# has no ground in this area at all.
“Time and space can be a bitch.”
–Gushie, Quantum Leap
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Snork!
I was wrestling with generics today (C#) and was surprised that I can't cast a List<T> to List<object>! 
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As leonej_dt pointed out, the real reason this is the case is C# does not have a built-in way to make an entire object read-only. In order for this to work, the cast would have to result in a List<object> that could be read, but not added to (otherwise we'd be adding objects of the wrong type to the collection!), unless somehow the Add method still required T's and not objects.
So a simple cast (as it currently stands) is not an option.
It's certainly theoretically possible to do, but it's just not something that's been done yet, not that I follow other languages very closely. It would probably require a lot of re-thinking and a lot of existing concepts would have to change.
Logan
“Time and space can be a bitch.”
–Gushie, Quantum Leap
{o,o}.oO( Looking for a great RSS reader? Try FeedBeast! )
|)””’) Built with home-grown CodeProject components!
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Oh, yeah, there is that... 
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From syntax point, yes.
But you don't program only with syntax. The library is important.
The libraries are very different.
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The libraries are different, but the basic concept behind them is the same: "Oh, poor programmer, he has to deal with low level details, let's make life simpler for him...".
To those who understand, I extend my hand.
To the doubtful I demand: Take me as I am.
Not under your command, I know where I stand.
I won't change to fit yout plan. Take me as I am.
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To that I call productivity... it doesn't mean that the programmer has less skills than the other that codes low level...
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That's called abstraction and it's the key to what makes building complex systems possible!
“Time and space can be a bitch.”
–Gushie, Quantum Leap
{o,o}.oO( Looking for a great RSS reader? Try FeedBeast! )
|)””’) Built with home-grown CodeProject components!
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Yes, but they don't let me mess with machine code, or even deal with the OS directly, NOT EVEN WHEN I WANT TO. The exceptions are Delphi, C and C++, but nobody uses Delphi and new programmers tend to dislike C and C++ and prefer either...
a) ... languages that are not compiled to machine code, but some sort of intermediate code that is either JITed or interpreted by a VM... which I hate because they add unnecessary type checkings and that kind of things, or,
b) ... script languages (yuck!). Theeeeeeeeeey aaaaaaaaaaaare slooooooooooooooooow. Peeeeeeeeeeerioooooooooooooood.
To those who understand, I extend my hand.
To the doubtful I demand: Take me as I am.
Not under your command, I know where I stand.
I won't change to fit yout plan. Take me as I am.
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That's not true... .NET Framework and Java let's you deal with OS directly:
.NET Framework -> PInvoke
Java -> JNI
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