From: Rick DeNatale <rick.denatale@...>
Date: 2009-11-29T01:35:45+09:00
Subject: Re: where is grep?

On Sat, Nov 28, 2009 at 11:10 AM, Robert Klemme
<shortcutter@googlemail.com> wrote:
> On 11/28/2009 08:27 AM, David A. Black wrote:
>>
>> Hi --
>>
>> On Sat, 28 Nov 2009, Florian Gilcher wrote:
>>
>>> Grep is not defined on Ruby 1.9-Strings.
>>>
>>> It was on Ruby 1.8-Strings, but only because they were belonging to the
>>> group of objects that mixed in Enumerable.
>>>
>>> There, grep behaves like this (line by line):
>>>
>>> x = "hello world baby girl"
>>> x.grep(/hello/)
>>> #=> ["hello world baby girl"]
>>> x = "hello\nworld\nbaby\ngirl"
>>> x.grep(/hello/)
>>> #=> ["hello\n"]
>>>
>>> The same can be done in Ruby 1.9 by just splitting the String beforehand.
>>> Arrays are Enumerable and thus
>>> still have grep:
>>>
>>> x = "hello\nworld\nbaby\ngirl"
>>> x.split("\n").grep(/hello/)
>>> #=> ["hello"]
>>>
>>> Note the absence of the line-break which might be intended or not :).
>>
>> I would probably do this in 1.9:
>>
>>   string.lines.grep(/pattern/)
>>
>> where lines returns an enumerator.
>
> Why not just string.scan(/pattern/) ?

Not the same thing

using 1.9

irb(main):001:0> a = "abe\nbob\nfred\njim"
=> "abe\nbob\nfred\njim"
irb(main):002:0> a.scan(/b/)
=> ["b", "b", "b"]
irb(main):003:0> a.lines.grep(/b/)
=> ["abe\n", "bob\n"]

a.lines.grep does the same thing that a.grep would do in 1.8, a.scan does not.

-- 
Rick DeNatale

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