Coding Bolt

What is IConvertible?

The IConvertible interface in .NET is part of the System namespace. It defines methods that convert values of a class or struct to common language runtime types. When you have a custom type and you want it to support conversions to built-in types (like int, double, or string), you implement the IConvertible interface.

Why Use the IConvertible Interface?

• Consistency: It provides a standard approach to conversions. Whenever developers see that a type implements IConvertible, they immediately know which methods to use for conversions.
• Integration: Many built-in .NET methods expect objects that implement this interface. By adhering to this pattern, you ensure a smooth experience for other developers who use your custom types.
• Flexibility: By controlling the conversion logic, you can ensure your objects are represented accurately when converted to other types.

Implementing the IConvertible Interface

Here’s a simple representation of our Temperature class:

public class Temperature : IConvertible
{
    public double Celsius { get; set; }

    public bool ToBoolean(IFormatProvider provider)
    {
        return Celsius < 0; // true if below freezing point
    }

    public byte ToByte(IFormatProvider provider)
    {
        throw new InvalidCastException("Cannot cast Temperature to Byte.");
    }

    // ... (similar methods for other conversions)

    public string ToString(IFormatProvider provider)
    {
        return $"{Celsius}°C";
    }

    public object ToType(Type conversionType, IFormatProvider provider)
    {
        if (conversionType == typeof(string)) return ToString(provider);
        throw new InvalidCastException($"Cannot cast Temperature to {conversionType.Name}.");
    }
}

Potential Pitfalls

• Implicit vs. Explicit: The IConvertible methods are all about explicit conversions. Developers should be aware that they’re performing a conversion and that there might be potential side effects.
• Error Handling: It’s essential to handle potential errors gracefully. If a conversion doesn’t make sense, throw a meaningful exception.