On Tue, Feb 12, 2013 at 1:19 PM, Joel Pearson <[email protected]> wrote:
> I've decided to inherit from array after all, since all I want to do
> with this is extend support for multidimensional arrays, but without
> overwriting any of Array's methods.
I usually do not engage in predictions since I don't have a crystal
ball but in this case I'll say: you won't get happy with that
approach. For example, anybody can override header values or complete
rows / columns violating your class's idea of internal state.
> Anyway, the obstacle I've hit is one I can avoid, but I was wondering
> whether I'm doing something wrong, or whether there's a nice Rubyish way
> around this. Here's a simplified version to demonstrate the issue:
>
> ___________________
> class Excel_Sheet<Array
>
> def initialize( val=[] )
> val = %w(A1 B1 C1 A2 B2 C2 A3 B3 C3).each_slice(3).to_a if val ==
> 'test'
> super ( val )
> end
>
> def skip_headers
> block_given? ? ( [ self[0] ] + yield( self[1..-1] ) ) : (
> self[1..-1] )
> end
What is this supposed to do? Ah, I think I see. I'd probably name it
differently, i.e. each_data_cell or something.
> def filter( header, regex )
> idx = self[0].index header
> skip_headers { |xl| xl.select { |ar| ar[idx] =~ regex } }
> end
>
> end
That combines too much logic in one method IMHO. I'd rather select a
row based on header and then I would use #select on that.
> So in short, my question is how can I return my class type after using
> Array's methods on my child-class?
Do you mean as return value from #map and the like? Well, you can't
without overriding all methods with this approach, I'm afraid. That's
one of the reasons why this approach does not work well. :-)
Kind regards
robert
--
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http://blog.rubybestpractices.com/
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