For reference I wrote this article about a year ago according to the commits at the
astruct
repo. I never submitted it because I got frustrated with the Ruby MRI source contribution process.astruct
could definitely use some cleaning up, but actually runs much better in 2.1.0 so the details still stand.
Hello Ruby Core,
In this Pull Request I have made a series of changes that I would like to be added to the Ruby stdlib library ostruct
. Before getting into anything I want to stress one thing: All changes are backwards compatible with the previous ostruct library. Any non-compatible changes are what I consider bug fixes and assumed behavior corrections.
First a list of problems with the current OpenStruct class:
OpenStruct
is used to create open structured objects and also is often used to give it’s open structure behavior to other classes. It is not always desirable or favorable to force the developer to inherit this class.OpenStruct
behaves somewhat similarly to a Hash
, but lacks a full duck typing and assumed behavior. Importantly to this point OpenStruct
can be built from, updated with, and dump to a Hash
. It even has a similar public interfaces like Hash#delete()
, but defined as OpenStruct#delete_field()
, or merge
and merge!
as OpenStruct#marshal_load()
.All of the public and private methods on the OpenStruct
are open to easy and annoying overloading. Some of the current methods use other public methods that are likely to be overloaded. A good example of this danger is the current OpenStruct#inspect
method, which calls OpenStruct#object_id
. It also causes problems like this:
example = OpenStruct.new
example.marshal_load = "example;example;example"
# => "example;example;example"
example.table
# => nil
example
# => #<OpenStruct marshal_load="example;example;example">
example.marshal_load
# => ArgumentError: wrong number of arguments (0 for 1)
example.marshal_load "red"
# => NoMethodError: undefined method `each_key' for "red":String
example
# => #<OpenStruct:0x3fd970c44120>
example.table
# => TypeError: can't convert Symbol into Integer
Second, in order to address the issues I was having I first built a gem to solve my problem. All of the below things I’ve done have been done in this gem and remain readily available for your use.
OpenStruct#delete_field
method only deletes the table key/value. This is not the expected behavior and ultimately leaves a lot of junk around in the method table.OpenStruct#marshal_load
it would correctly create getter and setter methods for each key/value, but it would also delete the entire table. I don’t believe this to be expected or intelligent behavior.OpenStruct
object and then redefines OpenStruct#frozen?
and it works. Freezing should stop any changes to the object.In order to allow developers to create both OpenStruct
-like objects and create regular OpenStruct
objects original I have created a module nested in the OpenStruct
class called Behavior
. That module contains all of the behavior OpenStruct
actually receives. Here’s an example of what this affords:
class Configuration < BasicObject
include OpenStruct::Behavior
end
Object#__send__
and many other important methods are named.OpenStruct#__freeze__
to OpenStruct#freeze
.OpenStruct#inspect
aliased to OpenStruct#__inspect__
) to avoid confusion. This works even when someone later overloads those method names.alias_method
you can now define a key/value “object_id” and still have access to the original OpenStruct#object_id
with OpenStruct#__object_id__
. This avoids the overloading bug explained previously.OpenStruct#__dump__
method. This was added to further Hash
like behavior.OpenStruct
as well as tests for the new features added in this pull request.In addition to fixing bugs, improving the interface and removing surprising behavior, I used two types of benchmarking: Benchmark#bmbm
and Benchmark#ips
(benchmark-ips
gem), both showing favorable results for my version of ostruct. Here are the results