C++ :: typedef As Data Type For Specialized Template Function In Class From Shared Library
Jul 19, 2013
I have a class "Result" with a single template function Set(const std::string& arName, T& val) and a specialization of this function Set<Real>(const std::string& arName, Real& val) where Real is a typedef for double. The class is in a shared library and I use it in my main program. If I do result->Set<GLOBAL::Real>("U", 100.0); the wrong template function is called!
I check this by the output with std::cout.
Maybe it's a problem with the typedef.
If I link the object file of the Result class directly to my main program (no shared library), it works.
how I want the code to look. Only problem is it doesn't work (Line 11). I have some experience with templates but I'm not a pro.
Basically I want the "Channels<3>" to be a type that I can use to specify a Cable with similar to vector<float/int> it would be Cable<Channels<2 or 3>>.
What have I messed up with the syntax?
#include <iostream> #include <vector> using namespace std;
/** This class build the singleton design pattern. Here you have full control over construction and deconstruction of the object. */ template<class T> class Singleton
[Code]....
I am getting error at the assertion points when i call to the class as follows:
I need to create the following brain damaging abomination:
I need a function pointer type to a function that has an argument of the same function pointer type and returns the same function pointer type.
The purpose is to enable a type of subroutine threading scheme for a small application specific scripting language. The question could just as well have been posted to the C forum.
This syntax works, but Payload is a generic type which I can coerce into the right pointer type via a cast. This is ugly IMHO. I could also hide it as a pointer in the FlipState class since I've forward declared this.
But this is an extra indirection in a performance critical part of the code, and also ugly.
Code: class FlipState ; typedef PayLoad (*FuncPtr) (FlipState *fs, PayLoad P) ; This syntax blows chunks using gcc on the other hand. Code: class FlipState ; typedef FuncPtr (*FuncPtr) (FlipState *fs, FuncPtr P) ;
[Code] .....
This is hardly surprising. The compiler could not possibly understand what I was defining in the typedef. I think what I need is some kind of way to forward declare a function pointer type and then redefine it properly.
Is such a think even possible or am I just SOL? This one is mind boggling. We know how to do this with classes or other complex data types, but the syntax eludes me for both C++ and C.
template <typename T> class Mediator { // bunch of code };
I want Mediator<int> to declare intClass friend, Mediator<std::string> to declare stringClass friend etc..., without having to redefine the entire specialization
I've been reading about libraries; How to make them, how to use them, the different types of libraries, etc..
When using a shared library, does the program require that library to be installed on the computer after the program has been compiled into an .exe?
Ie.. if somebody downloaded a "Helloworld.exe" that I had compiled on my computer using a shared library (that wasn't part of a standard operating system), would they also need that shared library on their computer for the program to run without errors?
and for Static Libraries, when I compile a program using a static library, does it include in the final binary only the functions of the library that are actually used, or does the compiler add in the entire library?
I am trying to pass a class as a type to a template class. This class's constructor needs an argument but I cannot find the correct syntax. Is it possible?
Here is an example of what I described above. I did not compiled it, it is for illustrative purpose only. And of course argument val of the myData constructor would be doing something more useful than simply initializing an int....
template <class T> class templateClass { templateClass() {};
[Code]....
My real code would only compile is I add the myData constructor:
myData () {};
and gdb confirmed that it is this constructor that get called, even with dummy(4).
A test program of mine loads a shared library (.so file). A function call in the shared library throws an exception that I am trying to catch in the main function of my test program. (I know that exception is being thrown for sure, I wrote the library to do that.)
However in the main program, the exception is not being caught. The flow of program goes past the catch block like no error has occurred. I am using g++ and I load the shared file using -l option. Only trying to load the program statically I got the following error:
/usr/bin/ld: cannot find -lmy-shared-library collect2: ld returned 1 exit status
I'm trying to implement a simple template array class, but when i came into the operator< i actually have to use a template :
my code is something like :
template<typename _Type, std::size_t _Size> class array { public :
[Code] ......
but i am having an error of shadows template param 'class _Type' is it w/ the name conflict between the array template parameter and the function template parameter ?
is there a way to have a template class respond to missing stuff in a template type ?
Code: template <typename Type> class MyClass { public: enum { ID = Type::ID }; // revert to 1 if Type::ID doesn't exist. };
If the Type passed to the template has an ID member (required to be an enum or a static const int), use it, if it is missing revert to a default value.
I can use this as a simplified way of configuring how MyClass works, without requiring Type to explicitely needing to define what it doesn't care about.
It needs to be resolved at compiletime, as it determines the number of elements in member array variables.
I have created a shared object in Ubuntu (libMYLIB.so). I am now trying to compile a simple test program (testmylib.c) to see if the shared object is properly built. I am getting an error that the build cannot find the shared object. My build command is:
test.cpp: In function ‘int main()’: test.cpp:20:30: error: no matching function for call to ‘func1(std::vector<int>&)’ test.cpp:20:30: note: candidate is: test.cpp:8:45: note: template<class T, class U> std::map<T, T> func1(U) test.cpp:8:45: note: template argument deduction/substitution failed: test.cpp:20:30: note: couldn't deduce template parameter ‘T’
I have created a template class called Queue that stores elements using linked list. I have also created a new type called Date.is there any way to output Date date using Queue functions?
#include <iostream> #include <string> #include <cctype> using namespace std; template <typename T> struct node{ T value; node<T> *next;
i want to use a class to print data stored as vector or array with different data types. i also want the print function two take more than one vector or array or combination of both so that they can be written to file as two columns. so i wrote the following class:
right now it has only one member function for printing two vectors. later i'll add additional functions as required.
note: there has to be template functions inside the class i also want the object to be global so that i need not pass it as an argument to other calling functions
then i want to call this template function in another ordinary function written in a seperate cpp file
these function declarations are put in a header file. so i need know whether i should put the declaration of the template function in the header to use the function in different functions
i want to use a class to print data stored as vector or array with different data types.
i also want the print function two take more than one vector or array or combination of both so that they can be written to file as two columns.so i wrote the following class:
right now it has only one member function for printing two vectors. later i'll add additional functions as required.
note: there has to be template functions inside the class / i also want the object to be global so that i need not pass it as an argument to other calling functions
then i want to call this template function in another ordinary function written in a seperate cpp file these function declarations are put in a header file. so i need know whether i should put the declaration of the template function in the header to use the function in different functions.
