Re: Range operator

[yaron]

Hi Chas and Jeff,


Thanks for your detailed answers. From chas answer I understand that this 
problem is addressed in perl 6. 
So, I will have to wait a bit....

In the meanwhile I will have to write my own "smart" flipflop.


BFN


Yaron Kahanovitch 
----- Original Message -----
From: "Chas Owens" <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
Cc: "beginners" <beginners@perl.org>
Sent: Thursday, August 9, 2007 10:36:29 AM (GMT+0200) Auto-Detected
Subject: Re: Range operator

On 8/9/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
> Hi,
>
> In the following example I have to print all the line from line "FROM" till 
> "END" not including the "FROM" line and the "END" line.
> That is if the file consists from the following lines:
>
> ds
> FROM
> 1
> 2
> 3
> 34
> 5
> 6
> END
> dsa
>
> I would like to print:
> 1
> 2
> 3
> 34
> 5
> 6
>
> I would like to accomplish that with range operator. But the following script 
> will add the FROM ann the END line to the output.
> Is there an efficient way to do that.
> In other words I would like to have range operator that will return true for 
> all the line inside the range not including the first and last line.
>
>
> BFN
>
>
> Yaron Kahanovitch
>
>
>
>  #!/usr/bin/perl
>
> while (<DATA>) {
>   print $_ if ( /FROM/ .. /END/ );
> }
>
> __END__
> ds
> FROM
> 1
> 2
> 3
> 34
> 5
> 6
> END
> dsa
>
>
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> http://learn.perl.org/
>
>
>

This mostly works, but doesn't do the right thing for START inside the range

#!/usr/bin/perl -n

print if /START/ .. /END/ and not (/START/ or /END/)

This works, but doesn't use the filpflop* operator

#!/usr/bin/perl

my $in = 0;
while (<>) {
    $in = 0 if /END/;
    print if $in;
    $in = 1 if /START/;
}

In Perl 6 the range and flipflop operators are being separated into ..
and ff respectively.  Both will have the ability to exclude the
extreme item on either side using ^.  So, in Perl 6 your code would
look something like this

#!/usr/bin/perl

use v6-alpha;

for =<> {
    print if /START/ ^ff^ /END/;
}

* in scalar context .. is the flipflop operator, in list context .. is
the range operator
** or at least this is how I read S03


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