Python to c++ conversion problem

[Ivan Vecerina]

"Akdes Serin" <e0427463 at student.tuwien.ac.at> wrote in message 
news:424141bb$0$12642$3b214f66 at tunews.univie.ac.at...
>I have a code in python like
> if eval('player.moveRoom(SeLinuxMud.Direction.' + x + ')'): # moveRoom
> function takes Direction enum as a parameter
>
> When I am trying to write this code in c++
> if (player->moveRoom(s[1])) //s[1] is a string so it outputs an error
> because of not taking enum as a parameter
>
> How can I change string to enum in c++?
Obviously C++ has no eval equivalent, but it also has limited
"introspection" at run-time. That is, the executing code has
no way to know the compile-time name associated with the enum
values.

One way to do this mapping manually would be:

#include <map>
#include <string>

enum ERoom
 { roomEntrance = 0
 , roomLobby = 1
 , roomCave = 2
 };
typedef std::map<std::string,ERoom> RoomLookup;
typedef RoomLookup::value_type RoomLookupEntry;
RoomLookupEntry roomLookupData[3] =
  { RoomLookupEntry("Entrance", roomEntrance )
  , RoomLookupEntry("Lobby",    roomLobby )
  , RoomLookupEntry("Entrance", roomCave )
  };
RoomLookup sRoomLookup(roomLookupData,roomLookupData+3);

Then in your code:
  if (player->moveRoom(sRoomLookup[ s[1] ]))

An annoyance with this approach is that your are writing
everything twice.
There are tricks to avoid that, using the preprocessor,
but it has its own drawbacks (see the thread associated with
http://groups.google.ca/groups?selm=QJGdnT8LXIMFEGLcRVn-1A%40comcast.com )

But for a game, most typically, the code would load
room descriptions from a data file at run-time, and
dynamically generate the equivalent of sRoomLookup.


I hope this helps,
Ivan
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