Pipes and Cascades

Pipes

You can chain kw messages with pipes
1 from: 2 to: 3 is single message with two arguments
1 from: 2 |> to: 3 is 2 messages with one argument each

Cascades

https://en.wikipedia.org/wiki/Method_cascading

x = a b; c; d has same effect as

a b
a c
a d
x = a

So its applying all the messages to the receiver, and then returns it.

With the help of cascade you can turn any API into a builder pattern, even if this was not intended!

btn = (Button new); 
    label: "Hello Adw";
    hexpand: true;
    vexpand: true;
    onClicked: [
        "clicked $n times!" echo
        n <- n inc
    ]
// same as
btn = Button new
btn label: "Hello Adw"
btn hexpand: true
btn vexpand: true
btn onClicked: [
    "clicked $n times!" echo
    n <- n inc
]

Combine |> with ; together

Sometimes it can be useful, but pls don't do it.

String boil -> Nothing!Error =
  Error throwWithMessage: "missing $this var"

String validate -> Unit!Error = [
  URL = "URL"
  SHA = "SHA"
  VERSION = "VERSION"

  this
    contains: URL     |> ifTrue: [URL boil];
    contains: SHA     |> ifTrue: [SHA boil];
    contains: VERSION |> ifTrue: [VERSION boil]
]

recipe_template = "SHA:234234234"
recipe_template validate

Last modified: 20 October 2024