[C++] Question about constructor

[erotavlas]

Hi,

I have the following class.



class Auto {

public:

enum AUTO_TYPE {SPORT, STANDARD};
enum PROBLEM_TYPE {COMBUSTION, ELECTRIC};


Auto(const std::string& autoType_, const std::string& engineType_) {

// sets the flags
if (autoType_ == "SPORT")
autoType = SPORT;
else (autoType_ == "STANDARD")
autoType = STANDARD;


if (engineType_ == "COMBUSTION")
engineType = COMBUSTION;
else (engineType_ == "ELECTRIC")
engineType = ELECTRIC;

}

private:

AUTO_TYPE autoType;
ENGINE_TYPE engineType;

};



The private members are initialized by the constructor and they are read from input stream. I would like to know if is a good idea to make the conversion from string type to enum inside the constructor. Is there a better way to do it?

Thank you

[NovaAesa]

I'd say it's fine to put simple things like that in the constructor (and by that I mean using an initialization list at the start of the constructor). Although, I think passing in the enum type directly to the constructor would be a "cleaner" way of doing things, seeing that your emum types are public.

[dwhitney67]

... I think passing in the enum type directly to the constructor would be a "cleaner" way of doing things, seeing that your emum types are public.

+1.

-------------

@ the OP - With your approach, you did not consider the scenario where one may pass in a string that does not match your expectations. Consider what would happen if "TRUCK" and "HYBRID" were passed in for the auto-type and engine-type. Your class would remain uninitialized!

Btw, the enum for ENGINE_TYPE is declared as PROBLEM_TYPE; was that a joke?

Anyhow, consider the following:


class Auto
{
public:
enum AutoType { SPORT, STANDARD, TRUCK };
enum EngineType { COMBUSTION, ELECTRIC, HYBRID };

Auto(AutoType autoType_, EngineType engineType_)
: autoType(autoType_),
engineType(engineType_)
{
// initialize class above... NOT HERE!
}

private:
AutoType autoType;
EngineType engineType;
};

Note how the constructor is implemented. Also, never used all-caps to define an enum declaration type. All-caps are typically used for constants (such as the enum members) or macros.