Creating a setter method that takes extra arguments in Ruby
indexer, methods, ruby, setter
Solution
It doesn't work because the parser doesn't allow it. An equals sign is allowed in expressions of the form `identifier = expression`, `expression.identifier = expression` (where identifier is `\w+`), `expression[arguments] = expression` and `expression.[]= arguments` and as part of a string or symbol or character literal (`?=`). That's it.
`gen.send(:allow=, 'a', 1, false)` would work, but at that point you could as well just give the method a name that doesn't include a `=`.
Problem
I'm trying to write a method that acts as a setter and takes some extra arguments besides the assigned value. Silly example: ``` class WordGenerator def []=(letter, position, allowed) puts "#{letter}#{allowed ? ' now' : ' no longer'} allowed at #{position}" end def allow=(letter, position, allowed) # ... end end ``` Writing it as an indexer works and I can call it like this: ``` gen = WordGenerator.new gen['a', 1] = true # or explicitly: gen.[]=('a', 1, true) ``` But when I try any of the following, the interpreter complains: ``` gen.allow('a', 1) = false # syntax error gen.allow=('a', 1, false) # syntax error ``` Why won't this work, am I missing the obvious?