3687l1.orig100664 777 330 575 7062321206 12126 0ustar ljeditorljedit3687l1 Listing 1. Header File for Base Class Shape #ifndef __SHAPE_H #define __SHAPE_H #include #include // base class for all shapes class shape { public: virtual void draw()=0; }; // typedef to make it easier to set up our factory typedef shape *maker_t(); // our global factory extern map > factory; #endif // __SHAPE_H 3687l2.orig100664 777 330 1357 7062321247 12153 0ustar ljeditorljedit3687l2 Listing 2. Header and Source File for Circle Class #ifndef __CIRCLE_H #define __CIRCLE_H #include "shape.hh" class circle : public shape { public: void draw(); }; #endif // __CIRCLE_H #include #include "circle.hh" void circle::draw(){ // simple ascii circle cout << "\n"; cout << " ****\n"; cout << " * *\n"; cout << " * *\n"; cout << " * *\n"; cout << " * *\n"; cout << " * *\n"; cout << " ****\n"; cout << "\n"; } extern "C" { shape *maker(){ return new circle; } class proxy { public: proxy(){ // register the maker with the factory factory["circle"] = maker; } }; // our one instance of the proxy proxy p; } 3687l3.orig100664 777 330 1323 7062321277 12150 0ustar ljeditorljedit3687l3 Listing 3. Header and Source for Square Class #ifndef __SQUARE_H #define __SQUARE_H #include "shape.hh" class square : public shape { public: void draw(); }; #endif // __SQUARE_H #include #include "square.hh" void square::draw(){ // simple ascii square cout << "\n"; cout << " *********\n"; cout << " * *\n"; cout << " * *\n"; cout << " * *\n"; cout << " * *\n"; cout << " *********\n"; cout << "\n"; } extern "C" { shape *maker(){ return new square; } class proxy { public: proxy(){ // register the maker with the factory factory["square"] = maker; } }; // our one instance of the proxy proxy p; } 3687l4.orig100664 777 330 6107 7062321327 12152 0ustar ljeditorljedit3687l4 Listing 4. Source for Main Program Invoking Dynamically Loaded Classes Circle and Square #include #include #include #include #include #include #include #include #include "shape.hh" // size of buffer for reading in directory entries static unsigned int BUF_SIZE = 1024; // our global factory for making shapes map > factory; int main(int argc, char **argv){ FILE *dl; // handle to read directory char *command_str = "ls *.so"; // command // string to get dynamic lib names char in_buf[BUF_SIZE]; // input buffer for lib // names list dl_list; // list to hold handles // for dynamic libs list::iterator itr; vector shape_names; // vector of shape // types used to build menu list shape_list; // list of shape // objects we create list::iterator sitr; map >::iterator fitr; // get the names of all the dynamic libs (.so // files) in the current dir dl = popen(command_str, "r"); if(!dl){ perror("popen"); exit(-1); } void *dlib; char name[1024]; i while(fgets(in_buf, BUF_SIZE, dl)){ // trim off the whitespace char *ws = strpbrk(in_buf, " \t\n"); if(ws) *ws = '\0'; // append ./ to the front of the lib name sprintf(name, "./%s", in_buf); dlib = dlopen(name, RTLD_NOW); if(dlib == NULL){ cerr << dlerror() << endl; exit(-1); } // add the handle to our list dl_list.insert(dl_list.end(), dlib); } int i = 0; // create an array of the shape names for(fitr=factory.begin(); fitr!=factory.end(); fitr++){ shape_names.insert(shape_names.end(), fitr->first); i++; } int choice; // create a menu of possible shapes to create and let the user make some while(1){ i = 1; for(fitr=factory.begin(); fitr!=factory.end(); fitr++){ cout << i << " - Create " << fitr->first << endl; i++; } cout << i << " - Draw created shapes\n"; i++; i cout << i << " - Exit\n"; cout << "> "; cin >> choice; if(choice == i){ // destroy any shapes we created for(sitr=shape_list.begin(); sitr!=shape_list.end();sitr++){ delete *sitr; } // close all the dynamic libs we opened for(itr=dl_list.begin(); itr!=dl_list.end(); itr++){ dlclose(*itr); } exit(1); } if(choice == i - 1){ // draw the shapes for(sitr=shape_list.begin(); sitr!=shape_list.end();sitr++){ (*sitr)->draw(); } } if(choice > 0 && choice < i - 1){ // add the appropriate shape to the shape list shape_list.insert(shape_list.end(), factory[shape_names[choice-1]]()); } } } 3687l5.orig100664 777 330 654 7062321356 12136 0ustar ljeditorljedit3687l5 Listing 5. Makefile CC = g++ LIBS = -ldl .cc.o: $(CC) -ggdb -c $< default: make testdcl OBJS = testdcl.o testdcl: testdcl.o $(CC) -rdynamic -o testdcl testdcl.o $(LIBS) libcircle.so: circle.o g++ -shared -Wl,-soname,libcircle.so -o libcircle.so circle.o libsquare.so: square.o g++ -shared -Wl,-soname,libsquare.so -o libsquare.so square.o all: testdcl libcircle.so libsquare.so clean: rm -f *.so *.o testdcl