From: SASADA Koichi <ko1@...>
Date: 2012-11-27T18:55:59+09:00
Subject: [ruby-core:50216] Re: [ruby-trunk - Feature #7434] Allow caller_locations and backtrace_locations to receive negative params

(2012/11/27 18:35), sam.saffron (Sam Saffron) wrote:
>> >  The last point is API design.
>> > "negative number" to this purpose is feasible?
> I like negative numbers cause it has some parity with the range APIs, eg: [1,2,3][0..-2] # skip last 

I agree that it is similar to the negative end of range.
However, range points *position* (index), not a size.

I think similar, but different concept cause confusion.

Ideas:

(1) Accept your idea.
    Define new concept.
   (Do not refer Array#[])

(2) Introduce 3rd argument to specify eliminate
    I feel it is bad.

(3) Consider argument

  (3-1) Accept Range object on 1st parameter
    caller(2..-2) #=> [foo2, ..., f/w2] on [ruby-core:50208] example.

  (3-2) ... no idea


(3-1) seems good?  It is same concept of Array#[].  Easy to explain.


>> > Any other example for other methods?
> I can not think of a use case for for the first param being negative, even though for arrays [1,2,3](-2..-1) makes sense, I can not think of a case where one would do caller_locations(-10, -1), the proposal is all about making the second param more flexible. 

I want to know other similar methods we can mimic.

-- 
// SASADA Koichi at atdot dot net