Provides a numbering object that will produce letters. Accepts four options
for numbering that will control how the letters are presented when given as
#[](index). This numbering object will only provide 26 values
("a" .. "z") unless :wrap is true.
:transform: | The symbol representing the method to be called on the letter. This must be
a method that does not require any arguments.
|
:postfix: | The value that will be appended to the letter presented by #[]. Defaults to
nil.
|
:prefix: | The value that will be prepended to the letter presented by #[]. Defaults
to nil.
|
:wrap: | If true, then indexes will be wrapped from "z" to
"a".
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a1 = Text::Format::Alpha.new(:postfix => ".")
puts a1[0] # => "a."
puts a1[1] # => "b.
puts a1[27] # => ""
a2 = Text::Format::Alpha.new(:prefix => "A.")
puts a2[0] # => "A.a"
puts a2[1] # => "A.b"
puts a2[27] # => ""
a3 = Text::Format::Alpha.new(:transform => :upcase)
puts a3[0] # => "A"
puts a3[1] # => "B"
puts a3[27] # => ""
a4 = Text::Format::Alpha.new(:wrap => true)
puts a4[0] # => "a"
puts a4[27] # => "b"