// This class opens a file but never closes it. Even its clients

// cannot close the file

class ResourceLeak {

private:

int sockfd;

FILE* file;

public:

C() {

sockfd = socket(AF_INET, SOCK_STREAM, 0);

}

void f() {

file = fopen("foo.txt", "r");

...

}

};

// This class relies on its client to release any stream it

// allocates. Note that this means the client must have

// intimate knowledge of the implementation of the class to

// decide whether it is safe to release the stream.

class StreamPool {

private:

Stream *instance;

public:

Stream *createStream(char *name) {

if (!instance)

instance = new Stream(name);

return instance;

}

}

// This class handles its resources, but does not do that in

// the constructor/destructor. It can be rewritten easily to

// be safer to use.

class StreamHandler {

private:

char *_name;

Stream *stream;

public:

C(char *name) {

_name = strdup(name):

}

void open() {

stream = new Stream();

}

void close() {

delete stream;

}

~StreamHandler() {

free(_name);

// stream should be deleted here, not in close()

}

}