Sha256: ee45df063e63783f9cbb76a11e3f040b48b78ba87f5f9751bf28de6b5478f23a
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Size: 1.71 KB
Versions: 34
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Stored size: 1.71 KB
Contents
# frozen_string_literal: true #-- # Most objects are cloneable, but not all. For example you can't dup methods: # # 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 # use an optimistic approach and are ready to catch an exception, say: # # arbitrary_object.dup rescue object # # Rails dups objects in a few critical spots where they are not that arbitrary. # That rescue is very expensive (like 40 times slower than a predicate), and it # is often triggered. # # That's why we hardcode the following cases and check duplicable? instead of # using that rescue idiom. #++ class Object # Can you safely dup this object? # # False for method objects; # true otherwise. def duplicable? true end end methods_are_duplicable = begin Object.instance_method(:duplicable?).dup true rescue TypeError false end unless methods_are_duplicable class Method # Methods are not duplicable: # # method(:puts).duplicable? # => false # method(:puts).dup # => TypeError: allocator undefined for Method def duplicable? false end end class UnboundMethod # Unbound methods are not duplicable: # # method(:puts).unbind.duplicable? # => false # method(:puts).unbind.dup # => TypeError: allocator undefined for UnboundMethod def duplicable? false end end end require "singleton" module Singleton # Singleton instances are not duplicable: # # Class.new.include(Singleton).instance.dup # TypeError (can't dup instance of singleton def duplicable? false end end
Version data entries
34 entries across 34 versions & 4 rubygems