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.
typedefs.hpp:
namespace GLOBAL {
typedef double Real;
} results.hpp
#include <iostream>
[Code] ....
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Nov 2, 2014
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;
[Code].....
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Feb 10, 2013
class IFoo {
virtual void Bar() = 0;
};
class FooAbstract {
virtual void Bar() {}
[Code] .....
How to call the Bar() method from FooTemplate in FooDerived::Bar()?
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Oct 12, 2013
Let me put it into the code snippet:
/**
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:
osgOpenCL::Context *cxt = osgOpenCL::Singleton<osgOpenCL::Context>::getPtr();
I tried commenting assertion statements and then the debugger just exits at the point where getPtr() is called.
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Mar 6, 2015
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.
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Aug 12, 2014
class intClass{};
class stringClass{};
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
template<>
Mediator<int>::friend intClass;
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Sep 23, 2012
Code:
template<class T>
class Convert {
T data;
public:
Convert(const T& tData = T()) : data(tData)
[Code] ....
Why do we use operator? Is float and double function names below?
Code:
Convert<int>::operator<float> float();
Convert<int>::operator<double> double();
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Jan 17, 2014
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?
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Oct 7, 2014
How to initialize a static member of a class with template, which type is related to a nested class?
This code works (without nested class):
#include<iostream>
using namespace std;
struct B{
B(){cout<<"here"<<endl;}
};
template<typename Z>
[Code] ,....
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Nov 30, 2013
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).
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Apr 18, 2013
class Tracker {
public:
static const int type;
typedef cv_types::CvType<type>::type_t type_t;
};
const int Tracker::type = 1;
gives me the error:
'I' : invalid template argument for 'cv_types::CvType', expected compile-time constant expression
Shouldn't the static const int be a compile time constant?
How would I specify it, so that it works?
PS.: The code works with #define type 1 at the top of the file and without the static const int.
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Jan 10, 2013
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
Why the exception is not getting caught.
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Aug 13, 2013
I want to create a simple shared library that exports a simple C API, just like llvm-clang.
The library should be compilable with any compiler and be used by a variety of languages, again just like clang.
For visual studio that is:
Code:
extern "C" __declspec(dllexport) void __cdecl myfunc(int arg);
The __cdecl is the issue here: i cannot seem to find a compiler agnostic way of specifying the use of cdecl.
So i went to see how my favorite C API libraries (ie clang) handle it.
none of them specify a calling convention at all!
Code:
#define CINDEX_LINKAGE __declspec(dllexport)
CINDEX_LINKAGE void clang_disposeIndex(CXIndex index); //exported
how does that work? How does the compiler know to use __cdecl and how would i link to it dynamically without that knowledge?
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Jan 22, 2013
I'm trying to find a C library for automating mouse clicks and keystrokes, something like the Python package AutoPy would be ideal.
Might have heard of Auto-it [URL] ...., which automates GUIs in Windows. Something like that would also be good, but my main OS is Linux.
I'm not sure whether it would be possible to create a shared library from the C source code in autopy.
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Dec 5, 2013
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 ?
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Feb 4, 2015
For example I want to get the type of std::vector<>::size_type without specifying a template argument.
Here's what I want to do:
std::vector<>::size_type x{5};
Is there any way this can be done?
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Jun 25, 2013
I'm getting unresolved link errors when I attempt to compile.
dNode.h
#ifndef DNODE_H
#define DNODE_H
template <class T>
class dNode {
[Code] ....
ERROR:
Error1error LNK2019: unresolved external symbol "public: __thiscall dStack<double>::dStack<double>(void)" (??0?$dStack@N@@QAE@XZ) referenced in function "void __cdecl stack_test(void)" (?stack_test@@YAXXZ)main.objprog09
Error2error LNK2019: unresolved external symbol "public: virtual __thiscall dStack<double>::~dStack<double>(void)" .......
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Jul 8, 2012
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.
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May 22, 2013
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:
gcc -lm -l /dir/mylib -lMYLIB.so -o testmylib testmylib.c
where /dir/mylib is where my source and libMYLIB.so reside.
What am I doing wrong?
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Jul 27, 2012
Is this really the preferred way to get the return type, for use in a derived class, of a function defined in the template parameter?
template<class PARAMETER> class C {
protected:
typedef typeof (reinterpret_cast<PARAMETER*>(0))->function() returntype;
};
This works just fine for me, but seems inelegant.
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Jul 28, 2013
I want to detect the type in a function template, like this:
template <class myType> myType Function (myType a, myType b) {
//Detect the myType
If (myType is int)
[Code] ......
Is that possible?
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Dec 9, 2013
I have this code:
#include <iostream>
#include <vector>
#include <map>
#include <string>
using namespace std;
[Code]...
and it does not compile.
The error 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’
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Mar 30, 2014
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;
[code]....
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Mar 26, 2014
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
class printdata
{
public:
template<typename T1,typename T2>
void SaveData( vector<T1> &data1,vector<T2> &data2, std::string var)
{
[Code]....
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
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Mar 26, 2014
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
class printdata {
public:
template<typename T1,typename T2>
void SaveData( vector<T1> &data1,vector<T2> &data2, std::string var){
std::ofstream myfile;
std::string filename;
[code].....
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.
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Feb 4, 2014
I'm trying to implement my own Stack class, for a generic data type. Here is what I have so far, but I'm having problems compiling the code:
Stack.h:
#ifndef STACK_H
#define STACK_H
#include <vector>
template< typename T >
class Stack {
[Code] .....
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