Thread: typedef and typename

I'm trying to return an iterator to a map from it's wrapper class. Finally got it to compile but wanted to ask why this didn't work.

Code:

template <typename key, typename value>
class MgrBase
{
    typedef typename std::map< key, value> MgrMap;
    typedef typename MgrMap::iterator MapIter;
    public:
         MgrBase();
         virtual ~MgrBase();
        
         MapIter Get(key ID);     
         size_t getMemSize();
};

template <typename key,typename value> 
MgrBase<key,value>::MapIter MgrBase<key,value>::Get(key ID)
{
    MgrMap::iterator map_iter(m_Objects.find(ID));
           
    return map_iter;
}

To get this to compile I had to add typename to the front of the function prototype and definition.

Code:

template<typename key,typename value>
class MgrBase
{
...
      typename MapIter Get(key ID);     
...
};

template <typename key,typename value> 
typename MgrBase<key,value>::MapIter MgrBase<key,value>::Get(key ID)
{
    MgrMap::iterator map_iter(m_Objects.find(ID));
           
    return map_iter;
}

Why wasn't this enough?

Code:

typedef typename MgrMap::iterator MapIter;

Seems to me the typename is in the typedef so why did I have to add typename to the declaration and definition?