> (irb):5:in `<main>': undefined method `name=' for <...> (NoMethodError)
> Did you mean? name
This error message is a bit roundabout. I assume the implication is that `name` is the getter and `name=` is the setter. And so, immutable objects don't have the setter method? But definitely could be worded much better than NoMethodError.
Disclaimer: I'm more of a Python/JS/TS person, and haven't used Ruby much.
(All Ruby operators work this way: something like `foo + bar` is short for `foo.+(bar)` for example.)
john.instance_variable_set(:@name, "John Doe")
john.send(:"instance_exec") do @name = "John Doe" end
But IMO/IME Ruby strikes a good balance here. You can break the rules but it really sticks out like a sore thumb. We avoid these backdoors like the plague.
Yes. This is extremely conventional/idiomatic Ruby. You'd be likely to come across this pattern not long after Hello World.
But that is the root cause - there is no such method.
The thing about 'Did you mean? name' is just a guess to help you.
And instead it throws anyone who hasn't extensive experience with Ruby's quirks into a spiral of misery.
(Or more realistically, your IDE underlines your error in red and you never even see the error message)
Though, to be honest, rather than an "instructive" error message... I sort of wish the language syntax itself forbade that space and simply forced you to write `foo.bar= 123` instead of `foo.bar = 123`.
I wonder if Matz himself has ever second guessed that choice he made in the 90s? =)
This syntactic sugar is definitely a bit weird, but it seems necessary in the "everything is an object" design, and to simultaneously meet Ruby's prime directive of maximizing developer happiness.
Can you imagine the howling from the haters if `x = 1` was a syntax error?
What do you think it should have said? Because this:
john.name = "John Doe"
is, literally, calling `name=` on `john`. But there is no such method.
What matters isn't "is" but "can act like".
IMO the root issue is the language syntax allows you to write `foo.bar = 123` instead of `foo.bar= 123` which kind of obscures the fact that `bar=` is a method.
If you've never written Ruby I 100% agree that the NoMethodError is perhaps confusing. However as others have noted this is just a really simple core concept you learn right away! This is your standard "oops, I called something that doesn't exist" message and contains everything you need to see where you went wrong.
99% of the time that message is all you need; for the other 1% you can use a debugger to pause things and see e.g. what methods `foo` does support.
I was.