Is it normal practice or very bad to nest maps?

Question

Is it normal practice or very bad to nest maps several levels?

        // name property     // name singal         // interval of Ranges      // values

typedef std::map<std::string, std::map<std::string, std::map<RangeSignalValue, std::string > > > sgHashSignals;

Answer 1

I've certainly done this. However, I'd break down the definition into digestible chunks:

typedef std::map<RangeSignalValue, std::string> RangeIntervalMap; 
typedef std::map<std::string, RangeIntervalMap> NameSignalMap;
typedef std::map<std::string, NameSignalMap>    NamePropertyMap;

Answer 2

If it makes sense in the context you're working in then I don't see any problems, other than it might be hard to read. Might it be possible to use typedef to make some of these nested maps easier to understand?