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33 lines
1.2 KiB
Markdown
33 lines
1.2 KiB
Markdown
# OpenStruct Has Bad Performance Characteristics
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The Ruby docs for `OpenStruct` have a [_Caveats_
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section](https://ruby-doc.org/3.4.1/stdlibs/ostruct/OpenStruct.html#class-OpenStruct-label-Caveats)
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that warns about the poor performance characteristics of `OpenStruct` relative
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to `Struct` and `Hash`.
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> This should be a consideration if there is a concern about the performance of
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> the objects that are created, as there is much more overhead in the setting
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> of these properties compared to using a Hash or a Struct. Creating an open
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> struct from a small Hash and accessing a few of the entries can be 200 times
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> slower than accessing the hash directly.
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This doesn't mean don't use `OpenStruct`, but do be aware of if you are using
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it in a hot path or if you are allocating and processing tons of them.
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If you turn on _Performance Warnings_ in Ruby, you'll see a warning message
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when allocating an `OpenStruct`.
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```ruby
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> require 'ostruct'
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=> true
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> os1 = OpenStruct.new
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=> #<OpenStruct>
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> Warning[:performance] = true
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=> true
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> os2 = OpenStruct.new
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(irb):6: warning: OpenStruct use is discouraged for performance reasons
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=> #<OpenStruct>
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```
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[source](https://www.reddit.com/r/ruby/comments/1d54mwl/comment/l6jgn59/)
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