In Ruby we can monkeypatch to easily add functionality to any class.
For example:
class String def yell! self.upcase + "!!!" end end
I'm extending the string class so that "hello".yell! outputs "HELLO!!!"
"hello".yell!
"HELLO!!!"
And now all strings in the program have access to the yell! method. ❤️
yell!
I'll add that this is sort of bonkers and an easy way to add some really hard-to-debug code to an app. Use with great fear and caution.
Lots of languages support that, including most obviously Javascript.
Interesting. Is that possible via class definitions (class syntax I mean) or only via the prototype syntax?
In F# it is also easy to add functionality to existing classes.
type String with member me.yell () = me.ToUpper() + "!!!"
You can also add functions to existing static classes (modules) too.
module Array = let shuffle arr = ... [| for i in 0 .. 23 do yield i * i |] |> Array.filter isOdd // filter is built-in |> Array.shuffle // i added
That's amazing that Ruby and other languages can extend built-in classes as well.
Anyways, to show off C#, here you go.
C# can extend any classes using extension method syntax.
using System; namespace extensionmethod { class Program { static void Main(string[] args) { Console.WriteLine("Hello World!".Yell()); } } public static class StringExtensions { public static string Yell(this string message) { return $"{message.ToUpper()}!!!"; } } }
Outputs
c:\misc\Sources\throwaway\extensionmethod> $ dotnet run HELLO WORLD!!!!
Note that you should mark the parameter with this
this
Yell(this string message)...
Here's how this would look in Kotlin:
fun String.yell() = this.toUpperCase()
Another interesting use is to create an Extension Property so you can print any type to the console, like this:
// Define the extension property val Any.sout get() = println(this)
Which can be used like:
fun main(args: Array<String>) { "hi".sout // prints hi 123.sout // prints 123 true.sout // prints true }
Since this is also available on any other class, any object you create will also have this property and it will call their toString().
class
toString()
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In Ruby we can monkeypatch to easily add functionality to any class.
For example:
I'm extending the string class so that
"hello".yell!
outputs"HELLO!!!"
And now all strings in the program have access to the
yell!
method. ❤️I'll add that this is sort of bonkers and an easy way to add some really hard-to-debug code to an app. Use with great fear and caution.
Lots of languages support that, including most obviously Javascript.
Interesting. Is that possible via class definitions (class syntax I mean) or only via the prototype syntax?
In F# it is also easy to add functionality to existing classes.
You can also add functions to existing static classes (modules) too.
That's amazing that Ruby and other languages can extend built-in classes as well.
Anyways, to show off C#, here you go.
C# can extend any classes using extension method syntax.
Outputs
Note that you should mark the parameter with
this
Here's how this would look in Kotlin:
Another interesting use is to create an Extension Property so you can print any type to the console, like this:
Which can be used like:
Since this is also available on any other
class
, any object you create will also have this property and it will call theirtoString()
.