From: Justin Collins <collinsj@...>
Date: 2006-10-26T02:50:38+09:00
Subject: Re: Functional Equivalency

Rick DeNatale wrote:

> On 10/25/06, dblack@wobblini.net <dblack@wobblini.net> wrote:
>
>> Hi --
>>
>> On Wed, 25 Oct 2006, tom.mancino wrote:
>>
>> > This works for multiple keywords:
>> >
>> > res = adwords.estimateKeywordList([AdWords::KeywordRequest.new(nil,
>> > 1000000, false, 'test', 'Broad'), AdWords::KeywordRequest.new(nil,
>> > 1000000, false, 'student', 'Broad')])
>> >
>> > This doesn't:
>> >
>> > keywords = ['test','student']
>> > res = adwords.estimateKeywordList([keywords.map! {|x|
>> > AdWords::KeywordRequest.new(nil, 1000000, false, x, 'Broad')} ])
>> >
>> > Aren't these statements functionaly equivilant, or have I missed
>> > something (probably!).....this may be an api problem as well.
>>
>> map! returns an array -- so in the second example, you've got an array
>> inside an array.
>
>
> I don't think so. They should be equivalent.  Here's a simplification
> of the OPs use case, with a dummy KeywordRequest class and JUST the
> expression for the argument:
>
> rick@frodo:/public/rubyscripts$ cat kwl.rb
> class KeywordRequest
>  def initialize(kwd)
>    @kwd = kwd
>  end
>
>  def inspect
>    "KWR(#{@kwd})"
>  end
>
> end
>
> puts "With array literal"
> p [KeywordRequest.new('test'), KeywordRequest.new('student')]
>
> keywords = ['test', 'student']
> puts "With map"
> puts "result=#{keywords.map {|x| KeywordRequest.new(x)}.inspect}"
> puts "keywords=#{keywords.inspect}"
> puts "with map!"
> puts "result=#{keywords.map! {|x| KeywordRequest.new(x)}.inspect}"
> puts "keywords=#{keywords.inspect}"
>
>
> rick@frodo:/public/rubyscripts$ ruby kwl.rb
> With array literal
> [KWR(test), KWR(student)]
> With map
> result=[KWR(test), KWR(student)]
> keywords=["test", "student"]
> with map!
> result=[KWR(test), KWR(student)]
> keywords=[KWR(test), KWR(student)]
>
> Both forms return a single level array of KeywordRequests.
>
> It is probably better to use :map instead of :map! unless he WANTS to
> clobber the array of keywords.
>
>

The point wasn't that map and map! are different - it's that the OP 
takes the result from map! and puts it inside an array (note the square 
brackets):

res = adwords.estimateKeywordList([keywords.map! {|x| AdWords::KeywordRequest.new(nil, 1000000, false, x, 'Broad')} ])

Which makes it an array within an array.

With the first form, it's a flat array:

res = adwords.estimateKeywordList([AdWords::KeywordRequest.new(nil, 1000000, false, 'test', 'Broad'), AdWords::KeywordRequest.new(nil, 1000000, false, 'student', 'Broad')])

The difference is probably why the second form is failing.


-Justin