# Some odd ball optimization tricks **URL:** \ **Category:** Ruby\ **Created:** [August 26, 2010, 1:53am UTC](https://www.ruby-forum.com/t/some-odd-ball-optimization-tricks/193878 "2010-08-26T01:53:58Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![amin1426](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/4da419/32.png) [@amin1426](https://www.ruby-forum.com/u/amin1426)\ **Post date:** [August 26, 2010, 1:53am UTC](https://www.ruby-forum.com/t/some-odd-ball-optimization-tricks/193878/1 "2010-08-26T01:53:58Z")
Here are two idioms which you may find useful, or at least curious, when trying to optimize the heck out of a Ruby script… require ‘pp’ # Similar to the “autosequence” facility in SQL. # Useful for replacing a complex key with a very simply POD proxy object. file\_sequence = 0 file\_index = Hash.new{|hash,key| file\_sequence+=1;hash[key] = file\_sequence} p file\_index[“foo”] p file\_index[“foo”] p file\_index[“bah”] p file\_index[“foo”] p file\_index[“bah”] pp file\_index # Similar to “to\_sym”, but can cope with spaces and weird characters… # So if tom1, tom2, tom3… go out of scope they can be garbage collected… # so if you end up just holding tomtom, you have only one copy of “tom” and you can test for # equality with .object\_id == .object\_id! one\_true\_string = Hash.new{|hash,string| hash[string] = string} tom1 = “tom” tom2 = “tom” tom3 = “#{tom1}” tom4 = tom2.clone tom5 = “t”+“o”+“m” toms = [tom1, tom2, tom3, tom4, tom5] pp toms pp toms.collect{|tom| tom.object\_id } tomtom = toms.collect{|tom| one\_true\_string[tom] } pp tomtom pp tomtom.collect{|tom| tom.object\_id } Running the above results in… 1 1 2 1 2 {“foo”=\>1, “bah”=\>2} [“tom”, “tom”, “tom”, “tom”, “tom”] [-609503848, -609503908, -609503888, -609503918, -609503978] [“tom”, “tom”, “tom”, “tom”, “tom”] [-609503848, -609503848, -609503848, -609503848, -609503848] – John C. Phone : (64)(3) 358 6639 Tait Electronics Fax : (64)(3) 359 4632 PO Box 1645 Christchurch Email : removed\_email\_address@domain.invalid New Zealand # ======================================================================= This email, including any attachments, is only for the intended addressee. It is subject to copyright, is confidential and may be the subject of legal or other privilege, none of which is waived or lost by reason of this transmission. If the receiver is not the intended addressee, please accept our apologies, notify us by return, delete all copies and perform no other act on the email. Unfortunately, we cannot warrant that the email has not been altered or corrupted during transmission. ---
**Author:** ![amin1426](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/4da419/32.png) [@amin1426](https://www.ruby-forum.com/u/amin1426)\ **Post date:** [August 26, 2010, 5:38am UTC](https://www.ruby-forum.com/t/some-odd-ball-optimization-tricks/193878/2 "2010-08-26T05:38:44Z")
On Wednesday, August 25, 2010 06:51:58 pm John C. wrote: > p file\_index[“foo”] > p file\_index[“bah”] > pp file\_index I guess I can think of a few rare instances this might be useful, but I’ve never had the keys be the bottleneck, or re-used keys enough in a script for this to matter. Still, interesting. > # Similar to “to\_sym”, but can cope with spaces and weird characters… …what? irb\> ‘foo bar’.to\_sym =\> :“foo bar” > “a@$bc☃!d\t”.to\_sym > =\> :“a@$bc☃!d\t” Worst thing that happens is 1.8 turns my beautiful Unicode into ugly hex escapes when pretty-printing, since it’s all just a binary string to 1.8. But if I print it straight out with puts, I get the original Unicode stuff back, and 1.9.1 handles this gracefully. I mean, I’ve got a friggin’ SNOWMAN in there. Just what characters have you discovered that you can’t make a string out of? And, as it suggests, you can use :“foo” or :‘foo’ as shorthand for the above. > # So if tom1, tom2, tom3… go out of scope they can be garbage > > collected… Same is true of any string you call to\_sym on. > you can test for > > # equality with .object\_id == .object\_id! I don’t know if String is smart enough to do that (I’d hope so), but Symbol certainly would be. So what does this solve over just using symbols, other than the fact that you could manually prune the one\_true\_string hash? ---
**Author:** ![amin1426](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/4da419/32.png) [@amin1426](https://www.ruby-forum.com/u/amin1426)\ **Post date:** [August 26, 2010, 11:10am UTC](https://www.ruby-forum.com/t/some-odd-ball-optimization-tricks/193878/3 "2010-08-26T11:10:39Z")
2010/8/26 John C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > p file\_index[“foo”] > p file\_index[“foo”] > p file\_index[“bah”] > p file\_index[“foo”] > p file\_index[“bah”] > pp file\_index I prefer irb(main):001:0\> file\_index = Hash.new {|h,k| h[k] = h.size} =\> {} irb(main):002:0\> file\_index[“foo”] =\> 0 irb(main):003:0\> file\_index[“foo”] =\> 0 irb(main):004:0\> file\_index[“bah”] =\> 1 irb(main):005:0\> file\_index[“foo”] =\> 0 irb(main):006:0\> file\_index[“bah”] =\> 1 irb(main):007:0\> file\_index =\> {“foo”=\>0, “bah”=\>1} > # Similar to “to\_sym”, but can cope with spaces and weird characters… > > # So if tom1, tom2, tom3… go out of scope they can be garbage collected… > > # so if you end up just holding tomtom, you have only one copy of “tom” and > > you can test for > > # equality with .object\_id == .object\_id! We have #equal? for that. > one\_true\_string = Hash.new{|hash,string| hash[string] = string} Note that this wastes a bit of memory because of the unfrozen string Hash optimization: irb(main):009:0\> one\_true\_string = Hash.new{|hash,string| hash[string] = string} =\> {} irb(main):010:0\> one\_true\_string[“a”] =\> “a” irb(main):011:0\> one\_true\_string.each {|k,v| puts k.equal? v} false =\> {“a”=\>“a”} Better freeze the string: irb(main):012:0\> one\_true\_string = Hash.new{|hash,string| hash[string.freeze] = string} =\> {} irb(main):013:0\> one\_true\_string[“a”] =\> “a” irb(main):014:0\> one\_true\_string.each {|k,v| puts k.equal? v} true =\> {“a”=\>“a”} Cheers robert