# Enumerable#detect\_result? **URL:** \ **Category:** Ruby\ **Created:** [November 24, 2007, 11:13pm UTC](https://www.ruby-forum.com/t/enumerable-detect-result/121180 "2007-11-24T23:13:43Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Yossef\_M](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/a87d85/32.png) [@Yossef\_M](https://www.ruby-forum.com/u/Yossef_M)\ **Post date:** [November 24, 2007, 11:13pm UTC](https://www.ruby-forum.com/t/enumerable-detect-result/121180/1 "2007-11-24T23:13:43Z")
Actual code from a recent project: ``` # This is bunk, but I'm tired and can't think of the right way to ``` do this # I was trying formats.detect, but that just returns the format, not the result result = nil formats.each do |f| result = f.process(mesg) break if result end In this context, ‘formats’ is an array of format objects, each of which represents a format a message can take. The process method takes in a message, checks it against the format object’s configuration, and returns either nil (if there was no match) or some useful value. Thanks to testing, my original concept of ``` formats.detect { |f| f.process(mesg) } ``` was rejected as being wrong. After all, I want the result of the process call, not the format object. I could go with collect/detect, but knowing I want the first makes that rather pointless, especially if processing could be expensive and the array could be long. Is there anything like Enumerable#detect\_result? Is there any desire for it? Is there any better name? ---
**Author:** ![Yossef\_M](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/a87d85/32.png) [@Yossef\_M](https://www.ruby-forum.com/u/Yossef_M)\ **Post date:** [November 25, 2007, 12:57am UTC](https://www.ruby-forum.com/t/enumerable-detect-result/121180/2 "2007-11-25T00:57:49Z")
On Nov 24, 2007 11:12 PM, Yossef M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > ``` > end > > ``` hmm yeah I also feel the need for something like map\_first sometimes, but there is no such beast. you can simplify the code above a little bit formats.each do | f | result = … break result if result end and if performance is not a problem the following is an alternative formats.map{ |f| f.process( mesg )}.detect{|x| x} if x can never be false that can be written as formats.map{ … }.compact.first or use facets formats.map\_if{ … }.first if there are possible false values. I do not know a standard or facets built in method that will stop iterating and return the block’s value, hopefully I am wrong 😉 HTH Robert ---
**Author:** ![Yossef\_M](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/a87d85/32.png) [@Yossef\_M](https://www.ruby-forum.com/u/Yossef_M)\ **Post date:** [November 25, 2007, 4:20am UTC](https://www.ruby-forum.com/t/enumerable-detect-result/121180/3 "2007-11-25T04:20:40Z")
On Nov 24, 4:12 pm, Yossef M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Is there anything like Enumerable#detect\_result? Is there any desire > for it? Is there any better name? Would this work? module Enumerable def detect\_result(ifnone=nil, &block) self.each { |x| result = block.call(x) return result if result } if ifnone then ifnone.call else nil end end end Regards, Jordan ---
**Author:** ![Yossef\_M](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/a87d85/32.png) [@Yossef\_M](https://www.ruby-forum.com/u/Yossef_M)\ **Post date:** [November 25, 2007, 7:00am UTC](https://www.ruby-forum.com/t/enumerable-detect-result/121180/4 "2007-11-25T07:00:47Z")
On Nov 24, 5:12 pm, Yossef M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > ``` > end > > ``` A little better. ``` result = nil formats.find do |f| result = f.process(mesg) end ``` T. ---
**Author:** ![Yossef\_M](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/a87d85/32.png) [@Yossef\_M](https://www.ruby-forum.com/u/Yossef_M)\ **Post date:** [November 25, 2007, 10:00am UTC](https://www.ruby-forum.com/t/enumerable-detect-result/121180/5 "2007-11-25T10:00:44Z")
Yossef, Just curious, but does the detect\_results method for the Enumerable module that I listed above, work for your example: results = formats.detect\_results { |f| f.process(mesg) } ? Regards, Jordan ---
**Author:** ![Yossef\_M](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/a87d85/32.png) [@Yossef\_M](https://www.ruby-forum.com/u/Yossef_M)\ **Post date:** [November 25, 2007, 3:53pm UTC](https://www.ruby-forum.com/t/enumerable-detect-result/121180/6 "2007-11-25T15:53:41Z")
On Nov 25, 3:00 am, MonkeeSage [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Jordan > I didn’t bother to try. It looks like it’ll work just fine. I like the > idea of specifying an alternate value if nothing matches, but it’s > always odd to pass two blocks to a method. ---
**Author:** ![Yossef\_M](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/a87d85/32.png) [@Yossef\_M](https://www.ruby-forum.com/u/Yossef_M)\ **Post date:** [November 25, 2007, 4:16pm UTC](https://www.ruby-forum.com/t/enumerable-detect-result/121180/7 "2007-11-25T16:16:04Z")
On Nov 25, 8:52 am, Yossef M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I didn’t bother to try. It looks like it’ll work just fine. I like the > idea of specifying an alternate value if nothing matches, but it’s > always odd to pass two blocks to a method. It’s actually the same thing that detect() does, I just made it return the value of the first True instance, rather than the object. If you look at the docs for Enumerable#detect, it’s the same semantics for ifnone. Regards, Jordan ---
**Author:** ![Yossef\_M](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/a87d85/32.png) [@Yossef\_M](https://www.ruby-forum.com/u/Yossef_M)\ **Post date:** [November 25, 2007, 7:31am UTC](https://www.ruby-forum.com/t/enumerable-detect-result/121180/8 "2007-11-25T07:31:09Z")
On Nov 25, 12:00 am, Trans [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > ``` > > result = f.process(mesg) > > > > ``` > > T. > Well, dang. I would say that’s obvious, but if that were actually the > case I would’ve thought of it. Nice one.