"main.cpp line 16:instantiated from here"
"156 templateClass.h no match for `CMike::SInts & != int'"
Battle of the templates! :(
Author
I'll try to explain this before I get run over by more compiler errors [smile].
I've got a template for a class where the class is both defined and declared in the header file.
Whenever I compile the project, which consists of:
main.cpp - which just uses the template class
templateClass.h - which contains the template class
I get plenty of these errors:
CMike is an ordinary class containing the SInts struct definition, used as the typename for the template class found in templateClass.h.
I've been battling these errors for hours and I must say, this template thingy is quite annoying.
If anyone has any tips for me or if I can be pointed to a basic template tutorial I'd be grateful.
Thanks in advance,
Ori
Templates are dead useful - commonly used to make smart pointers if you tend to forget what made something.
Okay, what this is saying is:
I'm a template where I'll take any class T, called SmartPtr.
Within the template and template code, you can use T as an arbitrary typename.
Infact you can also use template <typename T>.
This way, you can write a small amount of code, and let the compiler make the rest for you - as long as T implements any method you call on it inside the template you can do
You declare it like this, when you want it:
SomeRefCountObject MUST implement incRef() and decRef() since the template uses them.
A couple of really REALLY good books on this are Effective C++ and More Effective C++ by Scott Meyers. Everyone should have these.
Hope this helps.
[Edited by - _winterdyne_ on September 6, 2005 10:47:05 AM]
template <class T> class SmartPtr;{private: T* m_pPointee;public: SmartPtr(T* ptr) { m_pPointee = ptr; m_pPointee->incRef(); }; ~SmartPtr() { m_pPointee->decRef(); }; inline T* operator->() { return m_pPointee; }; // For a real smart pointer, you also need assignment, etc. // Don't forget a template casting operator or you won't get // inheritance working properly! // This is cut down :-)}Okay, what this is saying is:
I'm a template where I'll take any class T, called SmartPtr.
Within the template and template code, you can use T as an arbitrary typename.
Infact you can also use template <typename T>.
This way, you can write a small amount of code, and let the compiler make the rest for you - as long as T implements any method you call on it inside the template you can do
You declare it like this, when you want it:
SmartPtr<SomeRefCountObject> sptr(pRefCountObject);SomeRefCountObject MUST implement incRef() and decRef() since the template uses them.
A couple of really REALLY good books on this are Effective C++ and More Effective C++ by Scott Meyers. Everyone should have these.
Hope this helps.
[Edited by - _winterdyne_ on September 6, 2005 10:47:05 AM]
Author
Thanks. I think I followed the guidelines of the code you posted. Still can't find the problem.
Anyhow, I tried to avoid simply posting the code because there's really enough of it and I don't want to waste everyone's time but I guess my first post wasn't very clear...
Basically there are 2 files.
One is the header file containing the CList class which contains a list of many ListItem structures with each of them containing a changing type.
PrList.h:
The second file is main.cpp where the class is being used.
Any ideas?
Thanks in advance,
Ori
Anyhow, I tried to avoid simply posting the code because there's really enough of it and I don't want to waste everyone's time but I guess my first post wasn't very clear...
Basically there are 2 files.
One is the header file containing the CList class which contains a list of many ListItem structures with each of them containing a changing type.
PrList.h:
[SOURCE]template <typename T_classType>class CList{private: struct ListItem //A single list memeber { T_classType item; //List single data object ListItem* next; };ListItem* listStart; //A pointer to the list beginingListItem* listEnd; //A pointer to the list endingListItem* info; //The current item pointed at in the listpublic:CList();bool New(T_classType* newItem); //Creates a new object right before the//Many more functions I've cut out//..//..}; //Class declaration endtemplate <typename T_classType>bool CList<T_classType>::New(T_classType* newItem){//Do something}[/SOURCE]The second file is main.cpp where the class is being used.
[SOURCE]#include"PrList.h"void main(){CList<int*> MyList; //I've tried many other forms and still errors}//End.Generated errors:1) 174 prlist.h instantiated from `CList<int *>::~CList()'2)65 main.cpp instantiated from here[/SOURCE]Any ideas?
Thanks in advance,
Ori
This is a complete guess because you haven't provided any relevant details. Somewhere in your code you have something like this:
template< typename T > foo( T & x ) { int y; ... if ( x != y ) ... } ... CMike::SInts z; foo( z );
Your error is probably because you're using a non-templated struct from within the template to contain the template pointer, which is of an undefined type within the template.
Try templating ListItem as well:
Try this, should work.
Try templating ListItem as well:
[source lang="cpp]template <class T> class CList;{public:// This is a template-in-a-templatetemplate <class TItem> struct ListItem{ TItem* pListItem; ListItem * pNext};protected: // T is a valid typename because this is a template<T> ListItem<T>* pStart; ListItem<T>* pEnd; ListItem<T>* pCurrent; ...};Try this, should work.
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