Message precedence with parenthesis and how to check for it?

Question

In the AST I'm looking at RBMessageNode and I'd like to check if that node as precedence that differs from the standard. Noticed startWithParenthesis and stopWithParenthesis but they don't seem to produce the results I expected.

aNode startWithParenthesis ifTrue: [ ... do whatever ... ].

Is there a way to do this?

Answer 1

What's interesting here is the equivalence between the original condition

• detect nodes with a precedence that differs from the standard

and the one the parser needs to conform to the Smalltalk syntax

• the need for parenthesis.

As a good practice, when one finds these kinds of coincidences it is good to make them explicit by adding a second selector that conveys the other meaning. Given that in this case these are methods for testing, we have two options:

negative testing:

subvertsPrecedence
  ^self needsParenthesis

positive testing:

hasStandardPrecedence
  ^self needsParenthesis not

We should implemente the one that better express our intention. And if we decide to implement the two of them, it is better to re-writte the second as

positive testing:

hasStandardPrecedence
  ^self subvertsPrecedence not

in order to make it clearer the relationship with the other.