From: "prijutme4ty (Ilya Vorontsov)" <prijutme4ty@...>
Date: 2012-06-02T23:36:18+09:00
Subject: [ruby-core:45386] [ruby-trunk - Feature #6532] More methods for Hash and Array:  Hash#has_all_keys? and family, Array#delete_at for multiple arguments


Issue #6532 has been updated by prijutme4ty (Ilya Vorontsov).


And of course I forgot the most useful method (more suggestions about names highly appreciate) Array#selection and Hash#selection

alphabet = %w{a b c d e f g h i j}
alphabet.selection(0,1,5,7) # ==> ['a','b','f','h']
{A: 1, T: 4, G: 3, C: 5}.selection(:A,:C,:G,:T) # => [1,5,3,4]

I have several unsolved issues: 
1)what's the proper name for a method; 
2)whether this method should return array or enumerator
3) whether it should work with block like #map:
{A: 1, T: 4, G: 3, C: 5}.selection(:A,:C,:G,:T){|el| el.to_f} # => [1.0, 5.0, 3.0, 4.0]
or like #each
{A: 1, T: 4, G: 3, C: 5}.selection(:A,:C,:G,:T){|el| print el} # => 1534
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Feature #6532: More methods for Hash and Array:  Hash#has_all_keys? and family, Array#delete_at for multiple arguments
https://bugs.ruby-lang.org/issues/6532#change-26975

Author: prijutme4ty (Ilya Vorontsov)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 


I suggest introducing Hash methods: has_all_keys?, has_any_key?, has_none_key?, has_one_key? 
to write: input.has_all_keys? %w{A C G T}
instead of: %w{A C G T}.all?{|letter| input.has_key? letter}

and to write args.has_one_key?(:input_file, :input_string, :input_from_another_source, ...) instead of obvious but verbose code with iterating through keys


Also I suggest reimplement method Array#delete_at to work with multiple keys:
def delete_at(*args)
  args.sort.reverse{|index| current_version_of_delete_at index}
end

It helps not only writing multiple deletion code faster but also prevents mistakes with deleting elements from an array in arbitrary order


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