Re: calcaulation with unknown numbers of numbers and options fail

> Date: Fri=2C 28 Sep 2012 18:25:22 +0900
> From: [e-mail]
> Subject: Re: calcaulation with unknown numbers of numbers and options fai=
l
> To: [e-mail]
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> Roelof Wobben wrote in post #1077868:
> > Can you explain the how the operator and the reduce work.
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> First of all=2C I most correct the code: It should be
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> operator =3D options.empty? || options[:add] ? :+ : :-
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> to make addition the default.
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> What I've written down is simply the short form of "inject":
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> http://ruby-doc.org/core-1.9.3/Enumerable.html#method-i-inject
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> Instead of passing a block=2C you can also pass a method name or operator
> (as a symbol). The elements will then be aggregated using this
> method/operator.
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> So
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> [1=2C 2=2C 3].inject :+
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> is the same as
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> [1=2C 2=2C 3].inject {|sum=2C element| sum + element}
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> But it's obviously shorter. When you use the short form=2C it's common to
> use the method name "reduce" instead of "inject" (but both are the same
> method).
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> And the "operator" variable is used to specify the operator for "reduce"
> according to the option hash.
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> --=20
> Posted via http://www.ruby-forum.com/.


Thanks=20
So if I understand this well then you are saying when  options is empty or =
options =3D add then  add the numbers otherwise subtract the numbers ?

Roelof


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