Re: Constructing sequences
Derek Parnell wrote:
>
> Mario Steele wrote:
> >
> > Allright,
> >
> > Considering someone posted something about file i/o (Including Kat),
about this, and
> > the overwhelming evidence that pre-allocation is best way to go, here
should be an
> > extreamly fast version of loading a file into Memory (AKA Sequence):
>
> It seems that a lot of people have missed the original poster's point.
> Or maybe its just me 
But the way I read it is that they were trying
> to load each LINE of a text file into its own sub-sequence, rather than
> load the entire file into one single sequence. Thus a file with twenty
> lines would create twenty sub-sequences.
>
> Rob Craig's code is about the best so far for doing that, though I'm sure
> it could still be tweaked a bit more.
What to me, I try to answer the following Gordon's
question:
GW>> I am reading the data records in from a file so I don't see an
GW>> obvious way I could build the whole sequence at once. Wouldn't
GW>> I have to temporariliy store the records in another sequence,
GW>> incurring the same 'append' overhead anyway?
Really, the way with the *file size* is absent in the original
RDS documents, as far as I can see, so it is not *obvious way*,
I think.
But these ways exist.
So, any one can place a big file into single sequence at once
and do all he/she wants with that sequence - scan, find CR/LF,
make lines, records, parse them etc etc.
Mario takes this point in his attention too, I think.
Matt's approach is the simplest one - just create
a sequence with some extra elements to place a big
file without risk to go away from the sequence space
while reading a file.
Regards,
Igor Kachan
kinz at peterlink.ru
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