Re: Map problem

From:

Jerry Coffin <jcoffin@taeus.com>

Newsgroups:

comp.lang.c++

Date:

Fri, 11 Apr 2008 23:23:58 -0600

Message-ID:

<MPG.2269f51d7ae0cf31989c7d@news.sunsite.dk>

In article <6e90926f-18bc-42ac-bac6-16e590038a75
@x41g2000hsb.googlegroups.com>, naumansulaiman@googlemail.com says...

Hi, I want to create a map of named events from a const array.

eg std::map<std::string, HANDLE> this needs to be intialised so that

initially it will be contain the names of the all the events with a
NULL handle then
i can do the following

std::map<std::string, HANDLE> Events;
std::map<std::string, HANDLE>::iterator it;

const std::string[] { "EventName1", "EventName2", "EventName3"};

it = Events.begin();

while (it != Events.end())
{
Events[it->first] = CreateEvent(NULL,FALSE,FALSE, it->first.c_str())
++it;
}

So i f i ever need a new event all i need to do is add it to the array
and the event will be created
managed, destroyed just using the map.

However do i use the string array to initalise the map keys however?

I'd start by writing a wrapper class for the events:

// warning: untested code.
class event {
    HANDLE ev;
public:
// You usually don't want to name events unless you're sharing them
// across process boundaries.
    event() : ev(CreateEvent(NULL, FALSE, FALSE, NULL) {}

// haven't thought a lot about this -- might cause problem when copying
// an event. They're really more "identity" than "value" objects.
    ~event() { CloseHandle(ev); }

    DWORD wait(DWORD time = INFINITE) {
        return WaitForSingleObject(ev, time);
    }
};

Then you can put events into your map a bit more directly:

std::map<std::string, event> events;
char const *names[] = {"Event1", "Event2", "Event3"};

#define elements(x) (sizeof(x)/sizeof(x[0]))

for (int i=0; i<elements(names); ++i)
    events.insert(std::make_pair(names[i], event()));

--
    Later,
    Jerry.

The universe is a figment of its own imagination.