compilation error using std::map

This is a discussion on compilation error using std::map within the C++ Programming forums, part of the General Programming Boards category; Can you tell me why the "netDefaults.insert(...)" line causes the C++ compilation errors shown below? I'm using Visual Studio 2003. ...

  1. #1
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    compilation error using std::map

    Can you tell me why the "netDefaults.insert(...)" line causes the C++ compilation errors shown below? I'm using Visual Studio 2003. The code shown below is enclosed in an anonymous namespace to restrict its scope to the local file. Everything compiles fine if I comment out the "netDefaults.insert(,,,)" line. I use the make_pair() macro elsewhere (with different typed arguments) and it works fine in those other places. Note that those other places are outside the anonymous namespace.

    Getting rid of the anonymous namespace makes no difference. Removing the const modifier on the netDefaults declaration makes no difference. Adding "const EnumPrefIndicator" to the TDefaultSettingsMap declaration makes no difference.

    Code:
      typedef struct _TPrefInfo
        {
        EnumSimpleType    dataType;
        void*             pDefaultValue;
    
        _TPrefInfo( EnumSimpleType type, void *pData ) : dataType( type ), pDefaultValue( pData ){};
        } TPrefInfo;
    
      typedef std::map< EnumPrefIndicator, TPrefInfo* > TDefaultSettingsMap;
    
      const TDefaultSettingsMap netDefaults;
    
      // Populate the default settings...
        // IPS.
    
    --> netDefaults.insert( make_pair( prefIpsStatusModeNipsStatus, new TPrefInfo( stBool, (void*)true ) ) );



    Prefs.cpp
    c:\MyDocs\Entercept\netprefs_new\NetPrefs\prefs\Pr efs.cpp(121) : error C2143: syntax error : missing ';' before '.'

    c:\MyDocs\Entercept\netprefs_new\NetPrefs\prefs\Pr efs.cpp(121) : error C2501: 'netDefaults' : missing storage-class or type specifiers

    c:\MyDocs\Entercept\netprefs_new\NetPrefs\prefs\Pr efs.cpp(121) : error C2373: '`anonymous-namespace'::netDefaults' : redefinition; different type modifiers

    c:\MyDocs\Entercept\netprefs_new\NetPrefs\prefs\Pr efs.cpp(114) : see declaration of '`anonymous-namespace'::netDefaults'

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    You didn't specify the std namespace for make_pair.

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    A "using namespace std;" declaration was in an included header file.

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    Devil's Advocate SlyMaelstrom's Avatar
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    Ewwww.... never use "using" statements in headers.
    Sent from my iPadŽ

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    Are you sure EnumPrefIndicator, prefIpsStatusModeNipsStatus, stBool and EnumSimpleType are declared somewhere?

    Also, you shouldn't have the const there if you are calling insert on the map.

    If that doesn't help, maybe you could post more complete code.

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    Can you tell me why it's bad practice? Do your cautions apply even with a header guard in place?

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    Like I said in the original post, all compiles cleanly if the insert(...) line is commented out. That means to me that all the other types, variables, etc are properly defined and available, correct?

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    Tropical Coder Darryl's Avatar
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    On probably an unrelated note you can't make a map a const and then insert into it.

    Quote Originally Posted by dbeyer
    Can you tell me why it's bad practice? Do your cautions apply even with a header guard in place?
    The problem is that if someone else is using your class and include your header it will now break their code that is relying on the std namespace not being exposed.
    Last edited by Darryl; 03-02-2006 at 03:09 PM.

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    >> That means to me that all the other types, variables, etc are properly defined and available, correct?

    Probably, but not necessarily. Of course, I asked about prefIpsStatusModeNipsStatus and stBool, which in the code above are only used on the line that you commented out, meaning they could be the problem as well.

    Also check for a missing semicolon in the line above the one that gets the error.

    >> Can you tell me why it's bad practice? Do your cautions apply even with a header guard in place?

    Yes, the caution still applies. It is bad practice because it brings in the std namespace names to all files that include your header, as well as any file that includes a file that includes your header (and so on). Other files no longer have a choice. Putting a using directive in a source file is less bad, because only that source file will ever be affected.

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