Question

I’d have to say I’m no expert on using the STL. Here’s my problem, I have a class Called LdapClientManager which maintains a number of LDAP clients that are managed by ID. The container holding the LdapClients is declared as a member variable i.e.

typedef std::map<int, LdapClient *> LdapClientMap;
LdapClientMap _ldapClientMap;

The following function fails to compile with the error:

LdapClient * LdapClientManager::getLdapClient(unsigned int templateID)
{
    // Do we have an LdapClient
    LdapClientMap::const_iterator it = _ldapClientMap.find(templateID);
    if (it == std::map::end) {
        // no existing client, lets create it
        LdapClient * ldapClient = new LdapClient();
        if (ldapClient == NULL) {
            // TODO: handle out of memory condition
        }

        _ldapClientMap[templateID] = ldapClient;
        return ldapClient;
    }

    return it->second;
}

Unfortunately I get the following error at compile time, what does it mean. I haven’t found a solution in google as yet.

LdapClientManager.cc: In member function LdapClient*
LdapClientManager::getLdapClient(unsigned int)':
LdapClientManager.cc:33:template class std::map’ used without template parameters

Answer 1

Replace std::map::end with _ldapClientMap.end().
Also, new never returns 0, it throws an exception if the allocation fails.

Note that the program can be made much shorter.

LdapClient * LdapClientManager::getLdapClient(unsigned int templateID)
{
    LdapClient *& value = _ldapClientMap[templateID];
    if (value == 0)
        value = new LdapClient();
    return value;
}