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I wrote a template class which can accept various data types (I had different kind of data to handle)
All the data type I used with this template-class, are structures with common parameters.
Now I need to write a common code to all classes (I was thinking of a function with his own class) to use these "common" parameters.
The solutions I thought are:
1) Passing a void* pointer to the function and select the appropriate code for the datatype:
void Function( void *pointer_to_custom_data, ENUM_DATA_TYPE)
{
if(ENUM_DATA_TYPE == DATA_TYPE1)
// specific code for type1..
else if (ENUM_DATA_TYPE == DATA_TYPE2)
// specific code for type2..
...
}
2) Overloading in some way this function (don't know how though) so it recognize the type used and uses the specific code
Any better idea or suggestion on how to implement these?
---
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I'm not sure i completely understand your problem, but the first thought that comes to my mind is: why don't you have a common base class for your structures that contains the common "parameters" you are talking about, then you can make a method that takes a pointer/reference to this base class and does with the parameters what it should. Or do you mean that you have to do different things depending on the type of struct? Then use a virtual function declared in the base class and implement it according to your needs in all the subclasses. Am i misunderstanding you?
> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Sometimes you just have to hate coding to do it well. <
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You should, if possible, make the function part of the template class, thus ensuring type safety throughout. See the MSDN documentation on Templates[^] for more information.
It's time for a new signature.
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This looks likes bad design to me. Template class should not be explicitly aware of the types it can be used with. It can define the requirements in the types but that is all.
In your case it looks like better option is to use inheritance instead of template class. Unless of course you have presented a simplified picture.
I will suggest you inherit the structures from a common base class. This base class will contain common parameters and a pure virtual function. Inherited structures will override this function providing the type specific functionality.
-Saurabh
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If you want type specific code, you do not write a template class.
In some cases, for template classes you need a special implementation for a certain type.
In these cases you can do template specialization.
Assume you have a template class called Math -
template<typename T>
class Math
{
};
You may need special implementation for some data type like complex.
In this case you can specialize the template class for the complex data type.
template<>
class Math<complex>
{
};
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Function specialisation. Specialization if you're American.
Use the standard template case for the common code, specialisations for code specific to types. Like this:
#include <iostream>
template<class _Type>
void Fn(_Type const&)
{
std::cout << "Generic..." << std::endl;
}
template<>
void Fn<int>(int const&)
{
std::cout << "int specialisation" << std::endl;
}
int main()
{
Fn('a');
Fn(10);
}
The output you get is:
Generic...
int specialisation
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
CodeProject MVP for 2010 - who'd'a thunk it!
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I'm not dead, I was just looking at your suggestions and see whether they're appliable to my project.
Thank you guys but I realized some things:
1) I'm an idiot
2) More than half of my project has to be rewritten. I can't specializate template class because datatype are too much.
3) Project is slow as hell, I screwed it up with template of templates and at runtime it has to calculate every damn address it uses
I think I'm going to change a lot of things... thank you for your help!
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Hi 4288! My spontaneous reaction was, why does he use templates and not polymorphism... but I wanted to see what others say.
Perhaps it can help you in your design to have an abstract base class CObject and then derive classes from that base class with further specialisation. You would then only need one template for the base class (or if it is about storing data something like std::vector<CObject*>). In C++ virtual methods will be called virtual even via a base class pointer, quite handy. Hard to give better tips without seeing your architecture or requirements. Looks like Saurabh gave the same advice.
Hope it helps... and happy refactoring! 
/M
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Does setting a carriage return '/r' in callback
streamin Richeditctrl cause the text to go
to a new line
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I've no idea - but two suggestions…
1) Try it and see (try a '\n').
2) Enter some multi-line text into a rich-edit control and see what comes out when you use the EM_STREAMOUT message
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
CodeProject MVP for 2010 - who'd'a thunk it!
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I have a ES_AUTOSCROLL style maybe I
should take that out and try to size the editctrl
to some optimum size
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Maybe something about the mouse hook...
When I click some file's icon ,then how to return its path?
Thanks!
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I believe you should provide more details about what you want to do, till now it isn't obvious what you mean...
> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Sometimes you just have to hate coding to do it well. <
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I am doing a work like a monitor.
I mean when I click some file'icon on the desktop , for example ,system will return a messagebox says "this file's path is ...".
How can the system know what I have chosen?
I need system return the file's path.
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I personally don't know any standard way to do what you want (which of course does not mean there isn't any).
You could try hooking into explorer.exe, subclass the list control that hosts the icons on the desktop, or the window that receives notifications from the list view, or installing a (system-wide?) message hook, to find out when and to what the selection changes. Then you could use SHGetDesktopFolder[^] and use IShellFolder::EnumObjects[^] to find the path for the selected item, if it has any. How you would find out which icon belongs to which shell objects is beyond me at this point, you could try finding that object by the name the icon shows but this is probably a bad idea (for example if i have a "myFile.pdf" and a "myFile.txt" sitting on my desktop, i think both will have the name "myFile", the extension is hidden, or at least can be). If you are lucky then the items' itemdata contains something that can be used to identify them, for example a pointer to a IDList or somesuch, then you could even skip the "look up" part thorough the enumeration. This whole thing is just an idea and not a simple one at that...
> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Sometimes you just have to hate coding to do it well. <
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Oh, I am still a freshman and what you said is really hard for me..
Haha, still, thank you very much!
I will try.. 
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If you are a freshman i recommend starting with something simpler, anyways, good luck. 
> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Sometimes you just have to hate coding to do it well. <
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yeah, Thank you!
Any problems can I ask you for help?
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Sure.
> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Sometimes you just have to hate coding to do it well. <
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Hey everyone, new guy here.
I'm in a Game Physics class where we are learning OpenGL and a little bit of GLUT. In class, the pc's run Win XP and Visual C++ 2005 Express. I can get it to run my code in class with no problem. However, when I come home, for some reason I keep getting linker errors. I'm running Win7 Home Premium 64-bit. I've put the files into what I believe to be the correct folders, but whenever I compile and run, nothing. Anyone have any ideas? I'm starting to get really far behind in class because of this.
Thanks!
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epinez wrote: I come home, for some reason I keep getting linker errors.
epinez wrote: I compile and run, nothing
These conditions are contradictory. If you're having linker errors, what are they?
If you have linker errors, you can't "run".
The wonderful thing about the Darwin Awards is that everyone wins, especially the members of the audience.
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Sorry, should have been more clear. I attempt to compile and run, but nothing. The errors I get are: " error LNK2019: unresolved external symbol..."
Just to give insight to troubleshooting I've tried: I've put the GL and GLUT files in several different places and I've tried uninstalling VC++ and reinstalling it.
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Is GLUT built for 64 bits on your home system or did you bring home the 32 bit libraries?
The wonderful thing about the Darwin Awards is that everyone wins, especially the members of the audience.
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epinez wrote: The errors I get are: " error LNK2019: unresolved external symbol..."
Could you please give the exact error message. It helps to know which library is missing...
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Well unless you tell us what errors linker is compaining about how can we help you?
-Saurabh
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