From: Robert Klemme <shortcutter@...>
Date: 2008-11-04T02:18:37+09:00
Subject: Re: Clean way of pausing a loop?

On 03.11.2008 16:35, Kyle Schmitt wrote:
> It's Monday and it's relatively early, so I apologize if this isn't
> worded too well.
> 
> Is there a clean way of pausing a loop/printing status every N
> iterations?  I often use ruby to examine log files in a one-off
> fashion, and when dealing with files of 4-10 million lines, this is
> the sort of thing that becomes important.  Small files are, obviously,
> not as big of a deal.

You can use ARGF.lineno when reading from ARGF:

robert@fussel ~
$ seq 1 20  | ruby -e 'ARGF.each {|l| puts "."; puts ARGF.lineno if 
ARGF.lineno % 10 == 0}'
.
.
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10
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20


You can use IO.lineno when reading from a stream

robert@fussel ~
$ seq 1 20  | ruby -e '$stdin.each {|l| puts "."; puts $stdin.lineno if 
$stdin.lineno % 10 == 0}'
.
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10
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20

Or you can use #each_with_index.

robert@fussel ~
$ seq 1 20  | ruby -e '$stdin.each_with_index {|l,i| puts "."; puts i if 
i % 10 == 0}'
.
0
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10
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.

Or you can use $.:

robert@fussel ~
$ seq 1 20  | ruby -ne 'puts "."; puts $. if $. % 10 == 0'
.
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10
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20

I'm sure I forgot one or more variants. :-)

Cheers

	robert