45: Mainline

Whenever a Smalltalk expression contains multiple methods of mixed types, a few simple rules determine how the expression is to be evaluated:

• Unary messages are sent first.
• Then, binary messages are sent.
• Finally, keyword messages are sent.

Thus, unary messages are said to have the highest precedence; keyword messages have the lowest precedence; and binary messages have precedence in between.

Thus, Transcript show: 1746 printString produces the following event sequence:

• A unary printString message is sent to 1746.
• The Integer instance, 1746, answers a String instance, '1746'.
• A keyword show: message is sent to Transcript, with '1746' as the argument.
• The show: method causes a character sequence, 1746, to be displayed in the transcript.