Re: struct inheritance need?
Kagamin пишет: Weed Wrote: If you do not want to initialize repeatedly matrix inside the sub, which often cause each other, must be static matrices or declared as global (in relation to these procedures). You agree with that? What's problem? If you want static or global variables, you have them in D. Do you propose through mixin divide the code into parts? Well, why mixin? Just create different modules and place code according to its purpose to these modules. You do not think that it is better to add to language that would give 100% to use the opportunity of calculations at compile time. This greatly simplify the code and perfectly and logically fit into the language. Compile-time evaluation is just an optimization technique, which may or may not be applied without any change to source code, so it doesn't affect source code in any way, it just can't. In C++ you can't tell whether the code executes at compile time, as as of standard, it's completely up to the compiler to optimize code generation. Yeah, right. I propose that it be expanded to optimize the static arrays and classes.
Re: struct inheritance need?
Kagamin пишет: Weed Wrote: If you do not want to initialize repeatedly matrix inside the sub, which often cause each other, must be static matrices or declared as global (in relation to these procedures). You agree with that? What's problem? If you want static or global variables, you have them in D. Do you propose through mixin divide the code into parts? Well, why mixin? Just create different modules and place code according to its purpose to these modules. You do not think that it is better to add to language that would give 100% to use the opportunity of calculations at compile time. This greatly simplify the code and perfectly and logically fit into the language. Compile-time evaluation is just an optimization technique, which may or may not be applied without any change to source code, Incidentally, this is incorrect. In the event that it is impossible to calculate the static expression compiler immediately gives an error rather than moves calculation to run-time.
Re: struct inheritance need?
Weed Wrote: The problem is not in use templates. Templates are implementing some of the functionality of 2 types of structures matrices (normal and dynamic). But the structures do not inherit, then to add functionality matrix to other entities ( pixel, image etc) sites will have their list in a template return type. If structs don't suit you, don't use them. Classes are better suited for OOP as I said long ago and continue repeating it over and over. It contain list of all types (MatrixT and VectorT) for return. Will it add types of image and pixel and still others if needed. This is as good as manually implement a new object model. I'm sure any properly formalized problem is solvable. All you need is proper formalization and some design work. It is not necessary to suggest to wrap up pixel in a class - then it too cannot be initialized in a compile time. Sure it can't. Does it cause that big problems?
Re: struct inheritance need?
Kagamin пишет: Weed Wrote: The problem is not in use templates. Templates are implementing some of the functionality of 2 types of structures matrices (normal and dynamic). But the structures do not inherit, then to add functionality matrix to other entities ( pixel, image etc) sites will have their list in a template return type. If structs don't suit you, don't use them. Classes are better suited for OOP as I said long ago and continue repeating it over and over. It contain list of all types (MatrixT and VectorT) for return. Will it add types of image and pixel and still others if needed. This is as good as manually implement a new object model. I'm sure any properly formalized problem is solvable. All you need is proper formalization and some design work. It is not necessary to suggest to wrap up pixel in a class - then it too cannot be initialized in a compile time. Sure it can't. Does it cause that big problems? Sometimes it is the only way to avoid a large number of global ad
Re: struct inheritance need?
Kagamin пишет: Weed Wrote: that is, suppose that after some action should get a matrix matrix3x1 Well... if you want to template every piece of your code, this can cause disaster, so I think, this is not very good design. For example, multiplication method will be duplicated N*N*N times for all possible matrix size combinations. Only for really used combinations (i am using duck typing inside templates). In any case, unused functions in the resulting file is not included. I'd prefer run-time checks, though templates can be used for sure. This problem would help solve the availability of inheritance for structs or compile-time creation of class instances. But now the compiler can identify duplicate parts of the code, working with the same types
Re: struct inheritance need?
On Thu, 18 Dec 2008 07:24:34 -0500, Kagamin wrote: Static constructor can execute any valid D statements including construction of objects. A static constructor (also known as the Module constructor) executes at program run-time and not at program compile-time. I think Weed wants the ability to have the compiler build class objects at compile-time such that when a program first starts running, the objects are already fully formed in RAM just waiting to be used. -- Derek Parnell Melbourne, Australia skype: derek.j.parnell
Re: struct inheritance need?
Weed Wrote: I agree. In my case I chose to structure rather than a class because it can be initialized at compile time. But now I thing must be allowed to deploy class in the default data segment. And add the possibility of creating a object of class at compile time. If you want to use full blown OOP, class is your choise. There are static constructors for static initialization.
Re: struct inheritance need?
Weed wrote:
I should explain why it's important for me:
For example, I am making a matrix object(s)
It should be:
- any size
- with ability of making matrix instance of a given size in compile time.
- ability of creating matrix instance in runtime.
I have decided to make it struct because I need to create matrix
object in compile time. in real program I'll need matricies of
variable size and 3х1, 3х3, 6х6, 3х6 sizes (and may be other).
I want to make matrix template and insert in it with mixin operator
several structures of different sizes (and this structs are not store
his dimensions in each instance, of course: variables width and height
declared as invariant). By doing this I'll get several different
structures (matrix_dynamic, matrix3x3, matrix6x6 etc)
question is how those matricies can interoperate? They does not have
common parent (structures does not have inheritance) , so I can't
make common function for matricies of different sizes opAdd for
example, and have to do functions for all types of matricies.
How should I implement such a class In D properly?
It possible in C++, but I like some of the language D
The classical approach is to have helper template functions.
Essentially:
void doOpearation(mymatrix)(...)
{
}
Note this is compiletime polymorphisms.
Now if you want to add runtime polymorphism it is impossible to get away
from a cost. You can use a wrapper class like so:
interface CommonMatrix
{
operation()...
}
class PolymorphicMatrix(mymatrix) : CommonMatrix
{
operation()...
}
You'll probably find though that PolymorphicMartix should be some higher
level concept, like car, or entity.
The great thing about these techniques is that they give a whole load
more power then just using inheritance alone because you can essentially
attach many different behaviors to that struct.
I hope that was helpful.
-Joel
Re: struct inheritance need?
Weed: Planned in the future to implement inheritance of structs or the static creation of classes? Inheritance of structs: I think it's not planned. Structs in D are meant to be used for different things than classes. Yet, as time passes structs are gaining more power: you can't believe that very recently they have gained constructors/destructors too in D2. Probably in a system language conceptual purity isn't much appreciated :-) Static creation of classes (I think you mean creation of objects): it sounds like an interesting thing, I know of a system language that allows the creation of objects only at compile-time, and at compile-time it also performs several space optimizations among such objects (and such space optimizations often improve running speed a little). Bye, bearophile
Re: struct inheritance need?
bearophile пишет: Weed: Planned in the future to implement inheritance of structs or the static creation of classes? Inheritance of structs: I think it's not planned. Structs in D are meant to be used for different things than classes. Yet, as time passes structs are gaining more power: you can't believe that very recently they have gained constructors/destructors too in D2. Probably in a system language conceptual purity isn't much appreciated :-) I believe that the opportunity to place an object in memory, stack or heap is more important than the struggle against splicing. I think not worth taking structs and classes from C#. May be bytecode interpreter C# does not show the difference in speed between the allocation of memory by a small object + its using and the use of a static object, so developers C# decided to do so as done. (but I am not a specialist in the design of compilers :)) Static creation of classes (I think you mean creation of objects): it sounds like an interesting thing, I know of a system language that allows the creation of objects only at compile-time, and at compile-time it also performs several space optimizations among such objects (and such space optimizations often improve running speed a little). And in fact we come to making structs and classes similar except that classes can not be assigned by value. Such an option I like.
Re: struct inheritance need?
Bill Baxter пишет: 2008/12/16 Weed resume...@mail.ru: I should explain why it's important for me: For example, I am making a matrix object(s) It should be: - any size - with ability of making matrix instance of a given size in compile time. - ability of creating matrix instance in runtime. I have decided to make it struct because I need to create matrix object in compile time. in real program I'll need matricies of variable size and 3х1, 3х3, 6х6, 3х6 sizes (and may be other). I want to make matrix template and insert in it with mixin operator several structures of different sizes (and this structs are not store his dimensions in each instance, of course: variables width and height declared as invariant). By doing this I'll get several different structures (matrix_dynamic, matrix3x3, matrix6x6 etc) question is how those matricies can interoperate? They does not have common parent (structures does not have inheritance) , so I can't make common function for matricies of different sizes opAdd for example, and have to do functions for all types of matricies. How should I implement such a class In D properly? It possible in C++, but I like some of the language D Here's one way: http://www.dsource.org/projects/openmeshd/browser/trunk/LinAlg/linalg/MatrixT.d --bb necessarily need the ability to change the size of the matrix together with a static matrix it can be done using two types of matrices with a common parent.
Re: struct inheritance need?
Bill Baxter пишет: 2008/12/16 Weed resume...@mail.ru: I should explain why it's important for me: For example, I am making a matrix object(s) It should be: - any size - with ability of making matrix instance of a given size in compile time. - ability of creating matrix instance in runtime. I have decided to make it struct because I need to create matrix object in compile time. in real program I'll need matricies of variable size and 3х1, 3х3, 6х6, 3х6 sizes (and may be other). I want to make matrix template and insert in it with mixin operator several structures of different sizes (and this structs are not store his dimensions in each instance, of course: variables width and height declared as invariant). By doing this I'll get several different structures (matrix_dynamic, matrix3x3, matrix6x6 etc) question is how those matricies can interoperate? They does not have common parent (structures does not have inheritance) , so I can't make common function for matricies of different sizes opAdd for example, and have to do functions for all types of matricies. How should I implement such a class In D properly? It possible in C++, but I like some of the language D Here's one way: http://www.dsource.org/projects/openmeshd/browser/trunk/LinAlg/linalg/MatrixT.d --bb necessarily need the ability to change the size of the matrix together with a static matrix it can be done using two types of matrices with a single parent.
