Enumerators as strings

This is a discussion on Enumerators as strings within the C++ Programming forums, part of the General Programming Boards category; Is there a better way to extract enumerators names, other than using a vector<string> to match the enumeration? Code: enum ...

  1. #1
    (?<!re)tired Mario F.'s Avatar
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    Enumerators as strings

    Is there a better way to extract enumerators names, other than using a vector<string> to match the enumeration?

    Code:
    enum ESomeEnum { Opened, Closed, Locked };
    
    vector<std::string> SomeEnumStrings(3);
    SomeEnumStrings[0] = "Opened");
    SomeEnumStrings[1] = "Closed");
    SomeEnumStrings[2] = "Locked");
    
    int main() {
        CDoor myDoor;
        myDoor.setStatus(Closed);
    
        std::cout << "The door is " << SomeEnumStrings[myDoor.getStatus()] << "." << std::endl;
    }
    Last edited by Mario F.; 07-19-2006 at 10:04 AM.
    The programmer’s wife tells him: “Run to the store and pick up a loaf of bread. If they have eggs, get a dozen.”
    The programmer comes home with 12 loaves of bread.


    Originally Posted by brewbuck:
    Reimplementing a large system in another language to get a 25% performance boost is nonsense. It would be cheaper to just get a computer which is 25% faster.

  2. #2
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    I think map would be better than vector.

  3. #3
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    make sure you initialize enum

    Kuphryn

  4. #4
    Code Goddess Prelude's Avatar
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    >I think map would be better than vector.
    A map is better when the index is a string, but in this case it seems that the index is an integer. The only real issue is that the enum and vector have to keep the same order, which could be an annoying maintenance problem that a map handles automatically. Then again, the contiguous memory of a vector could be a deciding factor, as could the fact that a map is a more complicated data structure and there could be performance or footprint issues.

    That said, I would probably use a map.
    My best code is written with the delete key.

  5. #5
    Cat without Hat CornedBee's Avatar
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    You could do it the Mozilla way:

    some_include.h:
    Code:
    LOCAL_ENUM_VALUE_MACRO(Opened)
    LOCAL_ENUM_VALUE_MACRO(Closed)
    LOCAL_ENUM_VALUE_MACRO(Locked)
    user.cpp:
    Code:
    #define LOCAL_ENUM_VALUE_MACRO(v) v,
    enum ESomeEnum {
    #include "some_include.h"
    ESEDU_COUNT
    };
    #undef LOCAL_ENUM_VALUE_MACRO
    
    #define LOCAL_ENUM_VALUE_MACRO(v) #v,
    const char *const ESomeEnumStrings[] = {
    #include "some_include.h"
    }
    #undef LOCAL_ENUM_VALUE_MACRO
    Not necessarily pretty, but it works, and it keeps the two in sync.
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

  6. #6
    (?<!re)tired Mario F.'s Avatar
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    A map it will be. Thanks everyone

    On a not so related note... why am I not being able to create a vector at the global scope?
    Code:
    #include <vector>
    
    std::vector<int> myVector(3);
    myVector[0] = 1; // error
    myVector[1] = 1; // error
    myVector[2] = 1; // error
    
    int main() {
     /* ... */
    }
    I get the following error at every assignment attempt:
    expected constructor, destructor, or type conversion before '=' token
    The programmer’s wife tells him: “Run to the store and pick up a loaf of bread. If they have eggs, get a dozen.”
    The programmer comes home with 12 loaves of bread.


    Originally Posted by brewbuck:
    Reimplementing a large system in another language to get a 25% performance boost is nonsense. It would be cheaper to just get a computer which is 25% faster.

  7. #7
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    You can create the vector, but you can't have code outside of any function that assigns values to its data. If you want to initialize all the values to 1, you would use std::vector<int> myVector(3, 1). If you want more complex assignment, you'll have to put into a function.

    >> make sure you initialize enum
    What do you mean?

  8. #8
    (?<!re)tired Mario F.'s Avatar
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    What could be considered good norm to do this?

    Declare the global on my utils header file and define a init() function where these globals are defined?

    Code:
    // utils.h
    #include <vector>
    extern std::vector<int> myGlobal;
    
    //utils.cpp
    #include "utils.h"
    
    void init() {
        std::vector<int> myGlobal(3)
        myGlobal[0] = 1;
        /* ... */
    }
    /* ... */
    
    //main.cpp
    #include "utils.h"
    
    int main() {
         init();
        /* ... */
    }
    The programmer’s wife tells him: “Run to the store and pick up a loaf of bread. If they have eggs, get a dozen.”
    The programmer comes home with 12 loaves of bread.


    Originally Posted by brewbuck:
    Reimplementing a large system in another language to get a 25% performance boost is nonsense. It would be cheaper to just get a computer which is 25% faster.

  9. #9
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    Why do you need to have a global vector? Normally, it would be part of a class that does the initialization in the constructor.

  10. #10
    (?<!re)tired Mario F.'s Avatar
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    The vector (in fact it will be a few maps) will hold strings. Much like what is provided with a resource file. Some maps will map to enumerators, but the 3 biggest ones will provide the support for a series of random generated item names (ala Diablo II item generation); "brilliant longsword of maiming", "crude helm of Yark", ....
    The programmer’s wife tells him: “Run to the store and pick up a loaf of bread. If they have eggs, get a dozen.”
    The programmer comes home with 12 loaves of bread.


    Originally Posted by brewbuck:
    Reimplementing a large system in another language to get a 25% performance boost is nonsense. It would be cheaper to just get a computer which is 25% faster.

  11. #11
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    Ok. So put it in a class and do the initalization in the constructor. If you still want the data to be global, you can make a global instance of the class.

  12. #12
    (?<!re)tired Mario F.'s Avatar
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    Ok... sorry to bother you Daved. I'm having a blond day...

    But you mean putting each map inside his own class?
    I wouldn't need more than one instance of this class. Or is that you mean the map would be a static member of the class and there wouldn't be any need to create instances to use it?
    The programmer’s wife tells him: “Run to the store and pick up a loaf of bread. If they have eggs, get a dozen.”
    The programmer comes home with 12 loaves of bread.


    Originally Posted by brewbuck:
    Reimplementing a large system in another language to get a 25% performance boost is nonsense. It would be cheaper to just get a computer which is 25% faster.

  13. #13
    Registered User whiteflags's Avatar
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    I think that you should create your global vector, do the initializing in a function, and then work with that vector throughout the program. You just need a list of stuff right now. Right?
    Code:
    vector<string> PCEquipment;
    
    void setup_equipment() {
       if (PCEquipment.empty()) {
          PCEquipment.push_back( string("brilliant longsword of maiming") );
          PCEquipment.push_back( string("crude helmet of Yark") );
          PCEquipment.push_back( string("stein of mead") );
       }
    }
    what have you and then actually use the list throughout your game. Of course, you may find out later it's easier to refactor this list into it's own class. Except now that you have done some preliminary work with the list, you can refactor it into a user-defined type that does exactly what you need and you have made zero design presumptions too early.

    However because it's just a global vector I wouldnt give it it's own header. Keep everything in the source file for now, you can make header files later for this if you refactor it.

    I think that's what Dave wants to say, but even if he didn't, I wanted to make sure that I wrote this down.
    Last edited by whiteflags; 07-19-2006 at 01:16 PM.

  14. #14
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    Whether you put each map in its own class, or all of the maps into one class depends on how interrelated they are. If you wouldn't need more than one instance of the class, that's fine. Not all classes need to be used more than once to be effective. The benefit of putting the global data into a class (or classes) is that all the effort of creating, initializing, and maintaining the data is encapsulated into a single object.

    In the simple case, if your vector from post #6 was a non-static member of a class called MyVectorManager, and the constructor of that class initialized the vector data, like you tried to do globally, then you could just create a global instance of MyVectorManager and its constructor will automatically do that work for you. If you have lots of these maps and vectors to initialize, you can still follow the same technique.

  15. #15
    (?<!re)tired Mario F.'s Avatar
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    Ok gentleman. I believe I understood what's involved now.

    Thanks
    The programmer’s wife tells him: “Run to the store and pick up a loaf of bread. If they have eggs, get a dozen.”
    The programmer comes home with 12 loaves of bread.


    Originally Posted by brewbuck:
    Reimplementing a large system in another language to get a 25% performance boost is nonsense. It would be cheaper to just get a computer which is 25% faster.

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