From: ruby-core@... Date: 2017-12-10T23:59:09+00:00 Subject: [ruby-core:84151] [Ruby trunk Feature#14151][Feedback] Make Matrix#[]= public method Issue #14151 has been updated by marcandre (Marc-Andre Lafortune). Status changed from Open to Feedback greggzst (Grzegorz Jakubiak) wrote: > I don't even understand why this method hasn't been public since the beginning. The library was originally written such that Matrices are immutable. I can't speak to the exact reason for this choice as I'm not the original author, but I suspect it was to go along with the all the other numeric objects being immutable. Makes it more natural to do functional programming too. The method []= as it is written is also dangerous as it doesn't do any type checking. Try calling `m[1..2, 1..2] = 42` for example... > from the center of the matrix. I wonder what is that usecase. > So what I wanted to do is to create a zero matrix and the fill it in a proper way but I can't without using #[]=. You can build the values from arrays and call Matrix.[]: values = Array.new(5) { Array.new(5, 0) } values[2][2] = 42 m = Matrix[values] > shevegen (Robert A. Heiler) wrote: > Matrix seems a bit weird ... it does not allow for a Matrix.new either Indeed. As documented in the source, the official constructors are `Matrix.[]`, `rows`, `columns`, `build`, ... Note that the private `Matrix.new` makes no check on the validity of the given arguments. > The documentation is also lacking This is not a very constructive comment, nor is it particularly relevant to this issue. Better would be to open a separate issue, in which you enumerate which methods you fell lack documentation. Even better would be to provide a PR with the missing documentation. ---------------------------------------- Feature #14151: Make Matrix#[]= public method https://bugs.ruby-lang.org/issues/14151#change-68256 * Author: greggzst (Grzegorz Jakubiak) * Status: Feedback * Priority: Normal * Assignee: marcandre (Marc-Andre Lafortune) * Target version: ---------------------------------------- I don't even understand why this method hasn't been public since the beginning. I've come to a point when I have to create a matrix in a specific way using row and column indices and I can't use #build with a block because then indices go from the beginning of matrix whereas I have to from the center of the matrix. So what I wanted to do is to create a zero matrix and the fill it in a proper way but I can't without using #[]=. I know I can reopen class and that's what I'm doing but this just doesn't make sense. If we can change elements in an array like so using #[]= then why matrices can't use that as well? -- https://bugs.ruby-lang.org/ Unsubscribe: