Re: What is the meaning of $normalize->{$1}
Op donderdag 15 juni 2023 22:31:31 CEST schreef Claude Brown:
> Is there any prior mention of "$normalise" in the script?
Only now I see the first mentioning of $normalize as:
$normalize = {}
The naming of it is quite confusing to me. More logically would have been
"present".
Now I understand that it is a test to assure certain lines in the input file
should not be present more than once.
> Assuming there isn't, most likely "$normalise->{$1}" is building out a
> hash-table with "$1" as the key and a value of 1 at each entry.
> $normalise will be a reference to that hash.
>
> To check if this is correct, do this sometime after this code:
>
> use Data::Dumper;
> print Dumper($normalise);
Thanks a lot.
--
fr.gr.
Freek de Kruijf
--
To unsubscribe, e-mail: beginners-unsubscr...@perl.org
For additional commands, e-mail: beginners-h...@perl.org
http://learn.perl.org/
Re: What is the meaning of $normalize->{$1}
Freek de Kruijf writes:
> Hi,
>
> I am trying to understand fully a perl program with the following lines:
>
>} elsif( /^(\#?\s*(?:pickup|qmgr)\s+)(?:fifo|unix)(\s+.*)/ ) {
> if( defined $normalize->{$1} ) { next; } else { $normalize->{$1} = 1; }
> I do understand the first line, but I can not find what the second line is
> about.
$1 contains the content of the first capturing group in the matching
regexp. in this case, "#pickup", "#qmgr", "pickup", "qmgr"... etc.
$normalize->{$1} means: getting the corresponding value of $1 from the
HashRef $normalize.
$normalize->{$1} = 1 means: setting the corresponding value of $1 to 1.
`next` is a keyword for skipping the rest of loop, so it would seem to
me that these 2 lines is inside of a loop. I'm guessing $_ is the
iterator of the loop. Assuming that's the case, it appears to me
$normalize is used to keep track the occurance of the captured
words. Not how may times they occur, just if they occur or not.
--
Cheers,
Kang-min Liu
--
To unsubscribe, e-mail: beginners-unsubscr...@perl.org
For additional commands, e-mail: beginners-h...@perl.org
http://learn.perl.org/
Re: What is the meaning of $normalize->{$1}
} elsif( /^(\#?\s*(?:pickup|qmgr)\s+)(?:fifo|unix)(\s+.*)/ ) {
if( defined $normalize->{$1} ) { next; } else { $normalize->{$1} = 1;
}
if the string starting at the beginning of the line matches, $1 will
contain "zero or one #, zero or more whitespaces, either the word "pickup"
or "qmgr", one or more whitespace" - it's then being used as the kev value
in the hash referenced by $normalize - if that entry already has a true
value (probably a 1) don't do anything, otherwise, assign that key a 1 .
Note, to fully match, that string has to be followed by either "fifo" or
"unix" and 1 or more whitespaces. Everything (including those last
whitespaces) will end up $2.
I'm a tad puzzled as to what the purpose could be, there certainly are
easier ways to do this. The "use " is including the module
.pm in the code, so it's subs/methods etc can be used by the
program.
On Thu, Jun 15, 2023 at 2:29 PM Freek de Kruijf
wrote:
> Hi,
>
> I am trying to understand fully a perl program with the following lines:
>
>} elsif( /^(\#?\s*(?:pickup|qmgr)\s+)(?:fifo|unix)(\s+.*)/ ) {
> if( defined $normalize->{$1} ) { next; } else { $normalize->{$1} =
> 1; }
> I do understand the first line, but I can not find what the second line is
> about.
>
> As far as can see the tested line in $_, from a file, is all ASCII with
> lower
> case characters. At the begin of the perl program the is no "use
> ".
>
> --
>
> fr.gr.
>
> Freek de Kruijf
>
>
>
>
> --
> To unsubscribe, e-mail: beginners-unsubscr...@perl.org
> For additional commands, e-mail: beginners-h...@perl.org
> http://learn.perl.org/
>
>
>
--
a
Andy Bach,
afb...@gmail.com
608 658-1890 cell
608 261-5738 wk
