PILibrary Class Reference

Run-time library. More...

#include <pilibrary.h>

Public Member Functions
	PILibrary (const PIString &path_=PIString())
	Constructs PILibrary and load if "path_" not empty.
	~PILibrary ()
	Destroy PILibrary, unload if library was loaded.
bool	load (const PIString &path_)
	Load library with relative or absolute path "path_".
bool	load ()
	Load library with path() path.
void	unload ()
	Unload library if it was loaded.
void *	resolve (const char *symbol)
	Obtain exported library method with name "symbol". More...
bool	isLoaded () const
	Returns if library successfully loaded.
PIString	path () const
	Returns library path.
PIString	lastError () const
	Returns last occured error in human-readable format.

Detailed Description

Run-time library.

Synopsis

PILibrary allow you dynamically load external library and use some methods from it. PILibrary instance contains library pointer and unload library on destructor, so recommended to use it with new creation.

Main method of PILibrary is resolve(const char *), which returns void* pointer to requested method. One should test it to nullptr and convert it in pointer to the required method.

In case of C++ libraries it`s very important to use C-linkage of exported methods! You may also need to mark methods for export, e.g. __declspec(dllexport). You can include <piplugin.h> and use PIP_PLUGIN_EXPORT to mark exports with PIP.

extern "C" {
    __declspec(dllexport) int exportedSum(int,int);
    __declspec(dllexport) int exportedMul(int,int);
}

Usage

Library:

#include <piplugin.h>
 
extern "C" {
    PIP_PLUGIN_EXPORT int exportedSum(int,int);
    PIP_PLUGIN_EXPORT int exportedMul(int,int);
}
 
int exportedSum(int a, int b) {
    return a + b;
}
int exportedMul(int a, int b) {
    return a * b;
}

Program:

int main(int argc, char * argv[]) {
    typedef int(*MyFunc)(int,int);
    PILibrary * lib = new PILibrary();
    if (lib->load("mylib.dll")) {
        MyFunc fadd = (MyFunc)lib->resolve("exportedSum");
        MyFunc fmul = (MyFunc)lib->resolve("exportedMul");
        if (fadd) {
            int sum = fadd(1, 2);
            piCout << "sum =" << sum;
        } else {
            piCout << "Can`t resolve" << "exportedSum";
        }
        if (fmul) {
            int mul = fadd(10, 20);
            piCout << "mul =" << mul;
        } else {
            piCout << "Can`t resolve" << "exportedMul";
        }
    } else {
        piCout << lib->lastError();
    }
    delete lib;
}
 
// sum = 3
// mul = 30

Member Function Documentation

resolve()

void * PILibrary::resolve

(

const char *

symbol

)

Obtain exported library method with name "symbol".

Returns exported method with name "symbol" from loaded library. Method have to use C-linkage and marked to export, according to compiler specification.
C-linkage doesn`t provide information about return type and arguments, so you should manually convert obtained pointer to required method format before call.

Returns

void* pointer to method or
nullptr if method doesn`t exists or library not loaded