Re: Using and Querying Struct

Am 05.01.2013 13:40, schrieb Wayne Brissette:
> I'm trying to use the Stuct class to store some data. In my case, a
> bunch of data. But, in simplistic terms I've come up with the
> following example of what I'm looking for.
>
> class Mailinglist < Struct.new(:f_name, :l_name, :city) end
>

There is no need to subclass, just use

   Mailinglist = Struct.new(:first_name, :last_name, :city)

(Btw, your class name is misleading, `ListMember' would be
more accurate.)

> As an example, let's say I have two people John Smith and Jane Smith
> who live in Smithville. Is there an easy way to query an array
> containing Structs to determine of :l_name, and :city of with the
> array match and only produce one item from the array?

   data = [
     Mailinglist.new('Mike', 'Jones', 'Pineville'),
     Mailinglist.new('Jane', 'Smith', 'Smithville'),
     Mailinglist.new('John', 'Smith', 'Smithville'),
     Mailinglist.new('Sally', 'Taulton', 'Ashville')
   ]

   matches = data.select {|member| member.city == 'Smithville' && 
member.last_name == 'Smith' }
   matches.first
   # => #<struct Mailinglist first_name="Jane", last_name="Smith", 
city="Smithville">

Regards,
Marcus

> I know you could sort the array so all the data is sorted on l_name
> and then city. That would give you some order to the data:
>
> #<Struct Mailinglist f_name="Mike", l_name="Jones", city="Pineville">
> #<Struct Mailinglist f_name="Jane", l_name="Smith",  city="Smithville">
> #<Struct Mailinglist f_name="John",  l_name="Smith", city="Smithville">
> #<Struct Mailinglist  f_name="Sally", l_name="Taulton", city="Ashville">
>
>
> but would you have to iterate through the array to find all the
> matches to city, then l_name? I wouldn't think so, but I'm not sure
> how else to do it at this point.
>
> Wayne
>


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