[REBOL] Re: Processing files / Any AWK users?
From: brett:codeconscious at: 19-Nov-2001 16:04
Hi Gregg,
> If I'm processing a file, by lines, thus:
>
> foreach line read/lines/with file rec-sep [
>
> It appears that foreach doesn't call read on each pass, but I thought I'd
> ask to see if anyone knows, for certain. I know you can modify the block
> that foreach uses and it will see the changes, but I wasn't sure what
magic
> occurs in this scenario.
>
> The real question, I suppose, is: Should I cache the return value from
'read
> before using it with foreach, or is that unnecessary?
No foreach does not call read on each pass. Read returns a series which is
then given to foreach as a parameter.
By cache I assume you mean something like:
the-lines: read/lines/with file rec-sep
foreach line the-lines [...]
You would only do this if you need to access those lines again in your
script. I doubt there is any other memory effect other than creation a
single word "the-lines" and the prevention of the series being garbage
collected.
No opinion on the second question due to lack of knowledge :)
Brett.
