[ruby-core:18417] [Bug #512] String#% behavior

Issue #512 has been updated by Eero Saynatkari.


Nakada said: "It's an implementation detail"

I would disagree it is an implementation detail for the reason that Lars posted an example about and the inverse of the example is also true, if someone expects to have #to_ary called but it is not. I think perhaps we see the problem from different aspects. Am I correct in assuming that your point is that String#% always expects an Array argument (whether true Array or #to_ary)?

I suppose a third option would be to specify that the more specific conversion is attempted first (e.g. #to_s(tr) for %s, #to_i(nt) for %c etc.) and if it does not exist, #to_ary is attempted. To me it is more logical to never convert to Array when only one value is asked for to begin with.

My preference is only calling #to_ary when multiple substitutions exist, but it does not really matter which option is chosen. I do think it must be specified to behave one way or the other, even if it is the current implementation.

(In my opinion, any use of #to_ary, #to_int, etc. or even #to_a, #to_i can never be an implementation detail because it affects user code.)
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