Ruby version: 2.3.1
It does not appear that Ruby Structs can be declared using keyword params. Is there a way to do this within Struct?
Example:
MyStruct = Struct.new(:fname, :lname)
=> MyStruct
my_struct = MyStruct.new(fname: 'first', lname: 'last')
=> <struct MyStruct fname={:fname=>"first", :lname=>"last"}, lname=nil>
my_struct.fname
=> {:fname=>"first", :lname=>"last"}
my_struct.lname
=> nil
With Ruby 2.5, you can set the keyword_init option to true.
MyStruct = Struct.new(:fname, :lname, keyword_init: true)
# => MyStruct(keyword_init: true)
irb(main):002:0> my_struct = MyStruct.new(fname: 'first', lname: 'last')
# => #<struct MyStruct fname="first", lname="last">
keyword_init: true. Structs can automatically be initialized by keyword arguments. ruby-lang.org/en/news/2022/12/25/ruby-3-2-0-releasedmy_struct = MyStruct.new(fname: 'first', lname: 'last')
is the same as
my_struct = MyStruct.new({ fname: 'first', lname: 'last' })
#=> #<struct MyStruct fname={:fname=>"first", :lname=>"last"}, lname=nil>
(one argument) so fname is set equal to the argument and lname is set to nil, in the same way that x, y = [2]; x #=> 2; y #=> nil.
This is because Ruby allows one to omit the braces when a hash is the argument of a method.
You may wish to search SO for related questions such as this one.
MyStruct.new({fname: 'first'}, {lname: 'last'}) but that will give me a hash to work with rather than a string.
my_struct = MyStruct.new({fname: 'first'}, {lname: 'last'}); my_struct.fname #=> {:fname=>"first"}; my_struct.lname #=> {:lname=>"last"}. Does that answer your question?
NamedStruct class that inherits from Struct, and changes the initialization behavior to accept keyword arguments instead.