Input Conversion

1. About

Most data user inputs in a terminal is in string format, in order to allow for flexibility and to support complex types there are multiple ways to allow that conversion.

  1. Use types that implement IConvertible, works for every common language runtime type.
  2. Have type implement IStringConverter<T>, valid in most situation
  3. Register a IStringConverter<T> for a specific type in a StringConverterProvider

2. IStringConverter

Interface to be implement by types to allow conversion from and to string. It could be used in 2 ways

1. Self implement:

public class Person : StringConverter<Person> {
    public string Name { get; set; }
    public int Age { get; set; }

    public Person(): base(PersonToString, StringToPerson) { }

    public static string PersonToString(Person p) => $"{p.Name}:{p.Age}";
    public static Person StringToPerson(string s) {
        var data = s.Split(':');
        return new Person { Name = data[0], Age = int.Parse(data[1]) };
    }
}

2. Register a converter:

public class Person {
    public string Name { get; set; }
    public int Age { get; set; }

    public Person() { }

    public static string PersonToString(Person p) => $"{p.Name}:{p.Age}";
    public static Person StringToPerson(string s) {
        var data = s.Split(':');
        return new Person { Name = data[0], Age = int.Parse(data[1]) };
    }
}

// Register in a provider
var converter = new StringConverter<Person>(Person.PersonToString, Person.StringToPerson);
StringConverterProvider.Global.Register(converter);

3. StringConverter Provider

A StringConverterProvider is a class that allows to register and retrieve IStringConverter for a type. By default is used the StringConverterProvider.Global instance, so if a converter is supposed to be reused, it should be register here.

Registration example:

var converter = new StringConverter<Person>(Person.PersonToString, Person.StringToPerson);
StringConverterProvider.Global.Register(converter);

4. Factory

When it's time to convert a input, the StringConverterFactory is used to create the IStringConverter for the target type. To Create a converter the factory tries to get it following the steps:

  1. Current Provider (StringConverterProvider.Global by default)
  2. Self implementation, if type implements IStringConverter
  3. IConvertible if type implements it
  4. Throw an Exception