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author | Pratik Naik <pratiknaik@gmail.com> | 2010-01-17 03:26:20 +0530 |
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committer | Pratik Naik <pratiknaik@gmail.com> | 2010-01-17 03:26:20 +0530 |
commit | dba196cb7f8d34b93f6872e4a43737bb52019065 (patch) | |
tree | 97a2f784a2ec2bfae4f960af56a9280dad6f7774 /activesupport/lib/active_support/core_ext/object | |
parent | 6e3bee6cf1f0d2684152292db0a8b757249824fd (diff) | |
download | rails-dba196cb7f8d34b93f6872e4a43737bb52019065.tar.gz rails-dba196cb7f8d34b93f6872e4a43737bb52019065.tar.bz2 rails-dba196cb7f8d34b93f6872e4a43737bb52019065.zip |
Merge docrails
Diffstat (limited to 'activesupport/lib/active_support/core_ext/object')
-rw-r--r-- | activesupport/lib/active_support/core_ext/object/duplicable.rb | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/core_ext/object/duplicable.rb b/activesupport/lib/active_support/core_ext/object/duplicable.rb index a2d4d50076..b05325790c 100644 --- a/activesupport/lib/active_support/core_ext/object/duplicable.rb +++ b/activesupport/lib/active_support/core_ext/object/duplicable.rb @@ -1,3 +1,19 @@ +# Most objects are cloneable, but not all. For example you can't dup +nil+: +# +# nil.dup # => TypeError: can't dup NilClass +# +# 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 nil, false, true, symbols, numbers, class and module objects; true otherwise. |