[25219] in Perl-Users-Digest
Perl-Users Digest, Issue: 7464 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Tue Nov 30 06:10:55 2004
Date: Tue, 30 Nov 2004 03:10:10 -0800 (PST)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Tue, 30 Nov 2004 Volume: 10 Number: 7464
Today's topics:
Re: replace words in string with hash values <tadmc@augustmail.com>
Re: replace words in string with hash values <noreply@gunnar.cc>
Re: replace words in string with hash values <see@sig.invalid>
Re: replace words in string with hash values <tadmc@augustmail.com>
System command <varunjindal@yahoo.com>
Re: System command (Anno Siegel)
Re: System command <spamtrap@dot-app.org>
Re: Unix commands and perl <jwillmore@fastmail.us>
Re: Unix commands and perl (Anno Siegel)
why no syntax error? (Ronald Fischer)
Re: why no syntax error? <spamtrap@dot-app.org>
Re: why no syntax error? (Anno Siegel)
Re: why no syntax error? <bernard.el-haginDODGE_THIS@lido-tech.net>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Mon, 29 Nov 2004 18:27:38 -0600
From: Tad McClellan <tadmc@augustmail.com>
Subject: Re: replace words in string with hash values
Message-Id: <slrncqnfjq.1fb.tadmc@magna.augustmail.com>
Gunnar Hjalmarsson <noreply@gunnar.cc> wrote:
> wana wrote:
>> foreach (keys %h)
>> {
>> $a =~ s/\b$_\b/$h{$_}/g;
>> }
>>
>> I want to replace matches in string to hash key with hash value. I am
>> replacing acronyms with phrases where acronym is hash key. Is there a
>> better or different way?
>
> You have Perl search the whole string as many times as there are keys in
> the hash. With this approach, searching the string once is sufficient:
>
> my $keys = join '|', keys %h;
> $a =~ s/($keys)/$h{$1}/g;
But you better put the word boundaries back in though!
--
Tad McClellan SGML consulting
tadmc@augustmail.com Perl programming
Fort Worth, Texas
------------------------------
Date: Tue, 30 Nov 2004 03:28:36 +0100
From: Gunnar Hjalmarsson <noreply@gunnar.cc>
Subject: Re: replace words in string with hash values
Message-Id: <3124fcF36km4fU1@uni-berlin.de>
Tad McClellan wrote:
> Gunnar Hjalmarsson wrote:
>> wana wrote:
>>>
>>> foreach (keys %h)
>>> {
>>> $a =~ s/\b$_\b/$h{$_}/g;
>>> }
>>>
>>> I want to replace matches in string to hash key with hash value.
>>> I am replacing acronyms with phrases where acronym is hash key.
>>> Is there a better or different way?
>>
>> You have Perl search the whole string as many times as there are
>> keys in the hash. With this approach, searching the string once is
>> sufficient:
>>
>> my $keys = join '|', keys %h;
>> $a =~ s/($keys)/$h{$1}/g;
>
> But you better put the word boundaries back in though!
Yes, they were omitted by mistake; thanks for pointing it out.
--
Gunnar Hjalmarsson
Email: http://www.gunnar.cc/cgi-bin/contact.pl
------------------------------
Date: Mon, 29 Nov 2004 23:04:27 -0500
From: Bob Walton <see@sig.invalid>
Subject: Re: replace words in string with hash values
Message-Id: <41abeec8$1_4@127.0.0.1>
wana wrote:
> foreach (keys %h)
> {
> $a =~ s/\b$_\b/$h{$_}/g;
> }
>
> I want to replace matches in string to hash key with hash value. I am
> replacing acronyms with phrases where acronym is hash key. Is there a
> better or different way?
>
The only thing I've got to add to what's already been
said is to watch out for regexp metacharacters in your
hash keys. I have no idea what you might count as an
"acronym". If any metacharacters do appear, you can
use \b\Q$_\E\b as your regexp to quote them.
...
> wana (on pda)
--
Bob Walton
Email: http://bwalton.com/cgi-bin/emailbob.pl
------------------------------
Date: Mon, 29 Nov 2004 23:37:13 -0600
From: Tad McClellan <tadmc@augustmail.com>
Subject: Re: replace words in string with hash values
Message-Id: <slrncqo1o9.1rn.tadmc@magna.augustmail.com>
Bob Walton <see@sig.invalid> wrote:
> wana wrote:
>
>> foreach (keys %h)
>> {
>> $a =~ s/\b$_\b/$h{$_}/g;
>> }
>>
>> I want to replace matches in string to hash key with hash value.
> The only thing I've got to add to what's already been
> said is to watch out for regexp metacharacters in your
> hash keys. I have no idea what you might count as an
> "acronym". If any metacharacters do appear, you can
> use \b\Q$_\E\b as your regexp to quote them.
But if a metachar could be the first or last char, then
the word boundary probably won't match where you want it to...
--
Tad McClellan SGML consulting
tadmc@augustmail.com Perl programming
Fort Worth, Texas
------------------------------
Date: 30 Nov 2004 02:30:00 -0800
From: "Varun Jindal" <varunjindal@yahoo.com>
Subject: System command
Message-Id: <1101810600.015345.187340@z14g2000cwz.googlegroups.com>
hello,
i am using a unix shell command within my perl script using system
command.
lets say, i want to know what is hte system time (it is just an
example).
so i use the system command, but i want to put the output of the
command in a variable in the perl script.
how do i do it.
thanks in advance,
--Varun.
------------------------------
Date: 30 Nov 2004 10:52:03 GMT
From: anno4000@lublin.zrz.tu-berlin.de (Anno Siegel)
Subject: Re: System command
Message-Id: <cohjcj$sde$2@mamenchi.zrz.TU-Berlin.DE>
Varun Jindal <varunjindal@yahoo.com> wrote in comp.lang.perl.misc:
> hello,
>
> i am using a unix shell command within my perl script using system
> command.
>
> lets say, i want to know what is hte system time (it is just an
> example).
>
> so i use the system command, but i want to put the output of the
> command in a variable in the perl script.
> how do i do it.
Read the documentation of the function you are using, in particular
the third paragraph. perldoc -f system.
Anno
------------------------------
Date: Tue, 30 Nov 2004 06:00:33 -0500
From: Sherm Pendley <spamtrap@dot-app.org>
Subject: Re: System command
Message-Id: <T_GdnXpg49tPzzHcRVn-iw@adelphia.com>
Varun Jindal wrote:
> so i use the system command, but i want to put the output of the
> command in a variable in the perl script.
The docs for the system() function say, in part, "This is not what you
want to use to capture the output from a command, for that you should
use ..."
sherm--
--
Cocoa programming in Perl: http://camelbones.sourceforge.net
Hire me! My resume: http://www.dot-app.org
------------------------------
Date: Mon, 29 Nov 2004 20:12:30 -0500
From: James Willmore <jwillmore@fastmail.us>
Subject: Re: Unix commands and perl
Message-Id: <pan.2004.11.30.01.12.30.575917@fastmail.us>
On Mon, 29 Nov 2004 22:18:38 +0100, Michele Dondi wrote:
> On Mon, 29 Nov 2004 12:37:19 -0500, James Willmore
> <jwillmore@fastmail.us> wrote:
>
>>[jim@localhost jim]$ perl -e 'print [getgrgid($<)]->[0],"\n";'
>
> Not that I find it disturbing or incorrect, but what is this business
> of referencing and dereferencing?
>
> perl -le 'print +(getgrgid $<)[0]'
That's better. I always have to work a little bit harder than I need to :-)
Jim
------------------------------
Date: 30 Nov 2004 11:04:38 GMT
From: anno4000@lublin.zrz.tu-berlin.de (Anno Siegel)
Subject: Re: Unix commands and perl
Message-Id: <cohk46$sde$3@mamenchi.zrz.TU-Berlin.DE>
James Willmore <jwillmore@fastmail.us> wrote in comp.lang.perl.misc:
> On Mon, 29 Nov 2004 22:18:38 +0100, Michele Dondi wrote:
>
> > On Mon, 29 Nov 2004 12:37:19 -0500, James Willmore
> > <jwillmore@fastmail.us> wrote:
> >
> >>[jim@localhost jim]$ perl -e 'print [getgrgid($<)]->[0],"\n";'
> >
> > Not that I find it disturbing or incorrect, but what is this business
> > of referencing and dereferencing?
> >
> > perl -le 'print +(getgrgid $<)[0]'
>
> That's better. I always have to work a little bit harder than I need to :-)
That's what getgrgid() returns in scalar context anyway:
perl -le 'print scalar getgrgid $<'
is a little longer, but conceptually simpler.
Anno
------------------------------
Date: 30 Nov 2004 02:05:31 -0800
From: ronaldf@eml.cc (Ronald Fischer)
Subject: why no syntax error?
Message-Id: <219750c.0411300205.19d62317@posting.google.com>
I recently wrote the following nonsense:
if($arg = ~ /^\d{4}$/) { ... }
In case you don't see it immediately: I had erroneously typed a space between
the equal sign and the tilde.
To my surprise, this statement was executed without error message. $arg was set
to 294967295.
The tilde did bitwise complement of course, but on what? On a regexp? This
does not seem to make sense to me....
This was executed under Perl 5.6.1
Ronald
------------------------------
Date: Tue, 30 Nov 2004 05:18:42 -0500
From: Sherm Pendley <spamtrap@dot-app.org>
Subject: Re: why no syntax error?
Message-Id: <Mb-dnf4xBp-e1DHcRVn-hg@adelphia.com>
Ronald Fischer wrote:
> I recently wrote the following nonsense:
>
> if($arg = ~ /^\d{4}$/) { ... }
>
> The tilde did bitwise complement of course, but on what? On a regexp? This
> does not seem to make sense to me....
Pattern matching implicitly uses $_ if no other variable is used. I
expect you'd get the same results from this:
if ($arg = ~ ($_ =~ /^\d{4}$/)) { ... }
sherm--
--
Cocoa programming in Perl: http://camelbones.sourceforge.net
Hire me! My resume: http://www.dot-app.org
------------------------------
Date: 30 Nov 2004 10:21:18 GMT
From: anno4000@lublin.zrz.tu-berlin.de (Anno Siegel)
Subject: Re: why no syntax error?
Message-Id: <cohhiu$sde$1@mamenchi.zrz.TU-Berlin.DE>
Ronald Fischer <ronaldf@eml.cc> wrote in comp.lang.perl.misc:
> I recently wrote the following nonsense:
>
> if($arg = ~ /^\d{4}$/) { ... }
>
> In case you don't see it immediately: I had erroneously typed a space between
> the equal sign and the tilde.
>
> To my surprise, this statement was executed without error message. $arg was set
> to 294967295.
>
> The tilde did bitwise complement of course, but on what? On a regexp? This
> does not seem to make sense to me....
A regex that isn't bound by =~ applies to $_. That is what happens
here. The result of that match in scalar context is inverted and
assigned to $arg.
Anno
------------------------------
Date: Tue, 30 Nov 2004 11:20:21 +0100
From: "Bernard El-Hagin" <bernard.el-haginDODGE_THIS@lido-tech.net>
Subject: Re: why no syntax error?
Message-Id: <Xns95B1735AAB55Belhber1lidotechnet@62.89.127.66>
ronaldf@eml.cc (Ronald Fischer) wrote:
> I recently wrote the following nonsense:
>
> if($arg = ~ /^\d{4}$/) { ... }
>
> In case you don't see it immediately: I had erroneously typed a
> space between the equal sign and the tilde.
>
> To my surprise, this statement was executed without error message.
> $arg was set to 294967295.
>
> The tilde did bitwise complement of course, but on what? On a
> regexp?
No, on what the match operator returned.
--
Cheers,
Bernard
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
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Subject: Digest Administrivia (Last modified: 6 Apr 01)
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------------------------------
End of Perl-Users Digest V10 Issue 7464
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