self が任意の ASCII 互換エンコーディングとマッチ可能なら false を、そうでないなら true を返します。
例
# -*- coding:utf-8 -*-
r = /a/
p r.fixed_encoding? # => false
p r.encoding # => #<Encoding:US-ASCII>
p r =~ "\u{6666} a" # => 2
p r =~ "\xa1\xa2 a".force_encoding("euc-jp") # => 2
p r =~ "abc".force_encoding("euc-jp") # => 0
r = /a/u
p r.fixed_encoding? # => true
p r.encoding # => #<Encoding:UTF-8>
p r =~ "\u{6666} a" # => 2
begin
r =~ "\xa1\xa2".force_encoding("euc-jp")
rescue => e
e.class # => Encoding::CompatibilityError
end
p r =~ "abc".force_encoding("euc-jp") # => 0
r = /\u{6666}/
p r.fixed_encoding? # => true
p r.encoding # => #<Encoding:UTF-8>
p r =~ "\u{6666} a" # => 0
begin
r =~ "\xa1\xa2".force_encoding("euc-jp")
rescue => e
e.class # => Encoding::CompatibilityError
end
p r =~ "abc".force_encoding("euc-jp") # => nil
