15 May 19:35
Re: Contionnal sum
From: Simon Krahnke <overlord <at> gmx.li>
Subject: Re: Contionnal sum
Newsgroups: gmane.comp.lang.ruby.general
Date: 2008-05-15 17:35:15 GMT
Subject: Re: Contionnal sum
Newsgroups: gmane.comp.lang.ruby.general
Date: 2008-05-15 17:35:15 GMT
* Fernando Perez <pedrolito <at> lavache.com> (18:26) schrieb:
> Hi,
>
> I am wondering if it is possible to create a conditionnal sum.
>
> For instance I would like to do something like this:
>
> @total_amount = @orders.sum { |order| order.amount if order.paid == true
> }
@total_amount = @orders.inject(0) do | sum, order |
order.paid ? sum + order.amount : sum
end
or
@total_amount = @orders.select { | o | o.paid }. sum
BTW: Comparing a boolean value to true or false only shows you don't
understand booleans.
And if that order class is yours: I'd rather call the accessor »paid?«.
mfg, simon .... l
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