From: Eric Mahurin <eric_mahurin@...>
Date: 2005-05-02T06:42:57+09:00
Subject: Re: collections with values of fixed classes/lengths

> > Anybody know of any collection (i.e. Array/Hash) classes
> where
> > the keys and/or values can be assigned a fixed class?  And
> for
> > classes that have variable length objects the length be
> also
> > potentially fixed across the collection?  The main purpose
> of
> > doing this would be memory usage.  You wouldn't have to
> store
> > the class (and possibly object length and pointer to
> allocated
> > space) per element and instead just have the raw data in
> the
> > collection.  You would be able to get the same memory
> > utilization as C per element if done right.
> >
> > Here would be a few examples of what I'm talking about and
> how
> > much space per element it would take:
> >
> > - array of Floats (64 bits per element)
> > - array of N-bit integers (N bits per element)
> 
> For numerics there is for narray:
> http://raa.ruby-lang.org/project/narray
> 
> > - hash of 2-character strings (2*8 bits per key and Object
> per
> > value)
> > - array of array of 8 Floats (8*64 bits per line)
> 
> There's also pack and unpack which can be used to implement
> this.
> 
> > For dealing with large data structures, this could be
> > invaluable for memory usage.
> 
> "could" or "is"?  Do you really know that you need this or is
> this just 
> guessing?


Thanks Robert and Christian.  I think NArray will work for many
uses.

I still think a more general extension would be nice.  And
Robert, I guess you might say I'm guessing.  I'm new to ruby,
but from my perl usage, I know of many times I've dealt with
large amounts of data and would have wanted more C-like
efficiency.




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