訊息傳送

在 Smalltalk 中，你所做的幾乎所有操作都是向物件傳送訊息 （在其他語言中稱為呼叫方法）。有三種型別的訊息：

一元資訊：

#(1 2 3) size
"This sends the #size message to the #(1 2 3) array.
 #size is a unary message, because it takes no arguments."

二進位制訊息：

1 + 2
"This sends the #+ message and 2 as an argument to the object 1.
 #+ is a binary message because it takes one argument (2)
 and it's composed of one or two symbol characters"

關鍵字訊息：

'Smalltalk’ allButFirst: 5.
"This sends #allButFirst: with argument 5 to the string 'Smalltalk',
 resulting in the new string 'talk'"

3 to: 10 by: 2.
"This one sends the single message #to:by:, which takes two parameters (10 and 2)
 to the number 3.
 The result is a collection with 3, 5, 7, and 9."

語句中的多個訊息按優先順序進行評估

unary > binary > keyword

從左到右

1 + 2 * 3 " equals 9, because it evaluates left to right"
1 + (2 * 3) " but you can use parenthesis"

1 to:   #(a b c d) size   by:   5 - 4
 "is the same as:"
1 to: ( #(a b c d) size ) by: ( 5 - 4 )

如果要向同一物件傳送許多訊息，可以使用級聯運算子 ;（分號）：

OrderedCollection new
  add: #abc;
  add: #def;
  add: #ghi;
  yourself.

“這首先將訊息#new 傳送到 OrderedCollection 類（#new 只是一個訊息，而不是運算子）。它會產生一個新的 OrderedCollection。然後它將新的集合傳送三次訊息#add（帶有不同的引數），和你自己的資訊。“