💀 Symbols

Transcript

1. Erik Michaels-Ober (@sferik)
   RUG::B, 7 May 2015
   Symbols
   

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2. Symbols are Useless
   1. Calling Symbol#to_s on every symbol in your
   program would not change its semantics.
   2. Symbols are an archaic optimization. They were
   useful 20 years ago, but not today.
   3. Symbols and strings have converged into one type.
   

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3. "string".freeze.object_id

   ==

   "string".freeze.object_id

   # false on Ruby < 2.1
   # true on Ruby >= 2.1
   Symbols are ❄ Strings
   

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4. def measure
   init = Time.now
   yield if block_given?
   return Time.now - init
   end
   Benchmark
   

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5. N = 1_000_000
   measure { N.times { "string" } }
   measure { N.times { "string".freeze } }
   measure { N.times { :symbol } }
   Benchmark
   

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6. string: 0.126956
   freeze: 0.056473
   symbol: 0.056416
   Results
   

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7. 1. Symbols and frozen strings perform identically.
   2. Allocating a million strings takes about twice as long
   as allocating one string, putting it in into a hash
   table, and looking it up a million times.
   3. You can allocate a million short strings in about a
   tenth of a second on a typical 2015 laptop computer.
   Takeaways
   

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8. PowerBook 190
   33 MHz CPU
   8 MB RAM
   500 MB HDD
   $1850
   August 1995
   

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9. Ruby makes me happy.
   

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10. Symbols make me sad.
    

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17. :foo == "foo" # true
    Proposal
    !"#$%
    

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