1. Tommaso Urli
  2. JSON++
  3. Issues
Issue #5 new

Memory Consumption

Martin Grund
created an issue

The JSON::Value uses protected member variables to store each possible value. This means, that for each instantiation of a JSON::Value, memory for all types must be reserved. I would recommend using a union type for this to limit memory consumption.

Comments (3)

  1. Bitbucket user

    I would recommend to use a union and a type in Value. Then in the cast operators, check the type, and if types match, return the value of the corresponding member of the union, else return a default-constructed object for that type, or try to convert to the requested type from the actual type using a switch for all available types. This way, maybe if, e.g., the type is int, and the user requests a string, maybe it could be converted with a stringstream... Of course they could check the actual type stored. This way, the memory usage is reduced, and useful values are returned in most cases. This would resolve also issue #20.

  2. Bitbucket user

    example implementation: before anything, define uniou u with all the member types:

    /** Cast operator for float */
    long double as_float() const {
        case INT: return u.int_v; break;
        case FLOAT: return u.float_v; break;
        case BOOL: return u.bool_v?1.0:0.0; break;
            // or parse string to see if it contains exactly a number
        case STRING: return 0.0; break;
        case OBJECT: return 0.0; break;
        case ARRAY: return 0.0; break;
        case NIL: return 0.0; break;
        return 0.0;

    Maybe, members of the union other than inmediate types could be pointers and if the type is one of them, delete it in the destructor of Value.

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