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Re: Re: Re: Reading multiple lines?

by merlyn (Sage)
on Nov 29, 2000 at 20:02 UTC ( #43922=note: print w/replies, xml ) Need Help??

in reply to Re: Re: Reading multiple lines?
in thread Reading multiple lines?

I was just surprised that this wasn't as easy / neat to do as I expected. I'm quite pleased with my original map one liner, but nobody has really commented on whether it was really all that bad.
OK, I'll comment on that. In my mind map is a way to go from X to f(X) for a bunch of X's. If f(X) doesn't depend on X, it makes my brain go tilt a bit, but I can probably get used to it. Hence, I'll almost certainly try a different solution before I accept the void-arg map alternative.

Hmm. What you really probably have is a state machine. I could see a big Switch statement based on state (reading header A, reading header B, in the body) with eof(IN) at the top, and if eof is detected while in header A or B, then carp out.

See, I get worried about when the unusual happens. Maybe it's just my 30 years of programming, but any time I see someone write a "read 10 lines here" loop, I think "what if there aren't 10 lines?". That's what makes me good at QA. :)

-- Randal L. Schwartz, Perl hacker

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Re: Re: Re: Re: Reading multiple lines?
by rdw (Curate) on Nov 30, 2000 at 03:19 UTC

    Thanks for that - I appreciate your comments. I'll confess to being a bit of a map abuser - I tend to use it whenever I need to create a list or hash, although I do try to comment serious abuse whenever possible.

    Your QA point is a good one too - I work for a well known and well established website built almost entirely with perl and going through some old code I've found all sorts of mistakes - now I'm trying to import all the millions of lines of bad data it's created into a replacement system.

    Most of the mistakes are due to bad assumptions, often using regexps to match parts of strings out, but never testing whether the match was successful and getting a previous value of $1 or something. I sometimes wish that there were much more warnings about that sort of thing.

    Have fun,


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