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change return value of `duplicable?` with Ruby 2.4+

`NilClass`, `FalseClass`, `TrueClass`, `Symbol` and `Numeric` can dup
with Ruby 2.4+.

Ref: https://bugs.ruby-lang.org/issues/12979
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y-yagi committed Dec 7, 2016
1 parent 1373f9b commit 2cb855812066b64e7e10e40096a4c4e8e8256afb
@@ -1,3 +1,9 @@
* Change return value of `NilClass#duplicable?`, `FalseClass#duplicable?`,
`TrueClass#duplicable?`, `Symbol#duplicable?` and `Numeric#duplicable?`
to true with Ruby 2.4+. These classes can dup with Ruby 2.4+.

*Yuji Yaginuma*

* Remove deprecated class `ActiveSupport::Concurrency::Latch`

*Andrew White*
@@ -1,7 +1,7 @@
#--
# Most objects are cloneable, but not all. For example you can't dup +nil+:
# Most objects are cloneable, but not all. For example you can't dup methods:
#
# nil.dup # => TypeError: can't dup NilClass
# method(:puts).dup # => TypeError: allocator undefined for Method
#
# Classes may signal their instances are not duplicable removing +dup+/+clone+
# or raising exceptions from them. So, to dup an arbitrary object you normally
@@ -19,60 +19,85 @@
class Object
# Can you safely dup this object?
#
# False for +nil+, +false+, +true+, symbol, number, method objects;
# False for method objects;
# true otherwise.
def duplicable?
true
end
end

class NilClass
# +nil+ is not duplicable:
#
# nil.duplicable? # => false
# nil.dup # => TypeError: can't dup NilClass
def duplicable?
false
begin
nil.dup
rescue TypeError

# +nil+ is not duplicable:
#
# nil.duplicable? # => false
# nil.dup # => TypeError: can't dup NilClass
def duplicable?
false
end
end
end

class FalseClass
# +false+ is not duplicable:
#
# false.duplicable? # => false
# false.dup # => TypeError: can't dup FalseClass
def duplicable?
false
begin
false.dup
rescue TypeError

# +false+ is not duplicable:
#
# false.duplicable? # => false
# false.dup # => TypeError: can't dup FalseClass
def duplicable?
false
end
end
end

class TrueClass
# +true+ is not duplicable:
#
# true.duplicable? # => false
# true.dup # => TypeError: can't dup TrueClass
def duplicable?
false
begin
true.dup
rescue TypeError

# +true+ is not duplicable:
#
# true.duplicable? # => false
# true.dup # => TypeError: can't dup TrueClass
def duplicable?
false
end
end
end

class Symbol
# Symbols are not duplicable:
#
# :my_symbol.duplicable? # => false
# :my_symbol.dup # => TypeError: can't dup Symbol
def duplicable?
false
begin
:symbol.dup
rescue TypeError

# Symbols are not duplicable:
#
# :my_symbol.duplicable? # => false
# :my_symbol.dup # => TypeError: can't dup Symbol
def duplicable?
false
end
end
end

class Numeric
# Numbers are not duplicable:
#
# 3.duplicable? # => false
# 3.dup # => TypeError: can't dup Integer
def duplicable?
false
begin
1.dup
rescue TypeError

# Numbers are not duplicable:
#
# 3.duplicable? # => false
# 3.dup # => TypeError: can't dup Integer
def duplicable?
false
end
end
end

@@ -4,8 +4,13 @@
require "active_support/core_ext/numeric/time"

class DuplicableTest < ActiveSupport::TestCase
RAISE_DUP = [method(:puts)]
ALLOW_DUP = ["1", Object.new, /foo/, [], {}, Time.now, Class.new, Module.new, BigDecimal.new("4.56")]
if RUBY_VERSION >= "2.4.0"
RAISE_DUP = [method(:puts)]
ALLOW_DUP = ["1", Object.new, /foo/, [], {}, Time.now, Class.new, Module.new, BigDecimal.new("4.56"), nil, false, true, :symbol, 1, 2.3]
else
RAISE_DUP = [nil, false, true, :symbol, 1, 2.3, method(:puts)]
ALLOW_DUP = ["1", Object.new, /foo/, [], {}, Time.now, Class.new, Module.new, BigDecimal.new("4.56")]
end

def test_duplicable
rubinius_skip "* Method#dup is allowed at the moment on Rubinius\n" \

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