[31393] in Perl-Users-Digest
Perl-Users Digest, Issue: 2645 Volume: 11
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Wed Oct 21 18:09:43 2009
Date: Wed, 21 Oct 2009 15:09:07 -0700 (PDT)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Wed, 21 Oct 2009 Volume: 11 Number: 2645
Today's topics:
6 images in tile format(google maps) <dwayne.triffitt@gmail.com>
Re: 6 images in tile format(google maps) <ben@morrow.me.uk>
Re: 6 images in tile format(google maps) <smallpond@juno.com>
Re: FAQ 8.37 How do I find out if I'm running interacti <kst-u@mib.org>
Re: FAQ 8.37 How do I find out if I'm running interacti <brian.d.foy@gmail.com>
Re: FAQ 8.37 How do I find out if I'm running interacti <nospam-abuse@ilyaz.org>
Re: Getting current time in milliseconds <kst-u@mib.org>
Re: Getting current time in milliseconds <jurgenex@hotmail.com>
Re: Getting current time in milliseconds <laredotornado@zipmail.com>
Re: How would I do this in perl? <ben@morrow.me.uk>
Learning OO, object creation query. <justin.0908@purestblue.com>
Re: Learning OO, object creation query. <willem@stack.nl>
Re: Learning OO, object creation query. <rvtol+usenet@xs4all.nl>
Re: Learning OO, object creation query. <justin.0908@purestblue.com>
Re: Learning OO, object creation query. <justin.0908@purestblue.com>
Re: Learning OO, object creation query. (Randal L. Schwartz)
Re: prototypes <sreservoir@gmail.com>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Wed, 21 Oct 2009 13:26:32 -0700 (PDT)
From: Dwayne Triffitt <dwayne.triffitt@gmail.com>
Subject: 6 images in tile format(google maps)
Message-Id: <09de8268-56ab-44c9-9807-9fa023667d9c@g22g2000prf.googlegroups.com>
I want to know if there is a quicker way to add a Image into a frame
and tile it with others
eg perl.tk can add an image and i can set frames one by one, but the
code for the program is getting WAY!!!! to big (150 x 150 eg 5 km
square - i need 9 km square),
And with my code added to it, the program is all over the place and i
have over 1000 lines of code, i cant keep trace of......
Also on a foot note, can Serial be added to perl? can i read/write to
serial in perl and display its data in a label/text in perl.tk ??????
------------------------------
Date: Wed, 21 Oct 2009 21:56:07 +0100
From: Ben Morrow <ben@morrow.me.uk>
Subject: Re: 6 images in tile format(google maps)
Message-Id: <7494r6-nu2.ln1@osiris.mauzo.dyndns.org>
Quoth Dwayne Triffitt <dwayne.triffitt@gmail.com>:
> I want to know if there is a quicker way to add a Image into a frame
> and tile it with others
>
> eg perl.tk can add an image and i can set frames one by one, but the
> code for the program is getting WAY!!!! to big (150 x 150 eg 5 km
> square - i need 9 km square),
You do know about loops, right? Repetitive behaviour is something
computers are *really* good at.
> Also on a foot note, can Serial be added to perl? can i read/write to
> serial in perl and display its data in a label/text in perl.tk ??????
Look on http://search.cpan.org . You will also want to read the 'CPAN'
section in perldoc perlmodlib, and perldoc cpan.
You may also want to consider getting a book on Perl, or on general
programming concepts. The usual recommendation for beginners is
'Learning Perl'; see perldoc -q book for the full reference and also for
other (good) Perl books.
Ben
------------------------------
Date: Wed, 21 Oct 2009 14:33:31 -0700 (PDT)
From: smallpond <smallpond@juno.com>
Subject: Re: 6 images in tile format(google maps)
Message-Id: <0e07099b-102e-47d6-a203-324a6c01878a@d34g2000vbm.googlegroups.com>
On Oct 21, 4:26=A0pm, Dwayne Triffitt <dwayne.triff...@gmail.com> wrote:
> I want to know if there is a quicker way to add a Image into a frame
> and tile it with others
>
Might be easier to tile multiple images on a canvas.
> eg perl.tk can add an image and i can set frames one by one, but the
> code for the program is getting WAY!!!! to big (150 x 150 eg 5 km
> square =A0- i need 9 km square),
>
> And with my code added to it, the program is all over the place and i
> have over 1000 lines of code, i cant keep trace of......
>
The number of images should not affect the code size. Why
do you need 1000 lines of code? You just loop through all
of your (visible) images adding them to the display.
> Also on a foot note, can Serial be added to perl? can i read/write to
> serial in perl and display its data in a label/text in perl.tk ??????
It's bad form to put two unrelated questions in one usenet post.
Maybe this is why your code is undisciplined, too?
The answer is "Sure. Why not?"
------------------------------
Date: Wed, 21 Oct 2009 00:36:39 -0700
From: Keith Thompson <kst-u@mib.org>
Subject: Re: FAQ 8.37 How do I find out if I'm running interactively or not?
Message-Id: <lnzl7lw648.fsf@nuthaus.mib.org>
PerlFAQ Server <brian@theperlreview.com> writes:
[...]
> 8.37: How do I find out if I'm running interactively or not?
>
> Good question. Sometimes "-t STDIN" and "-t STDOUT" can give clues,
> sometimes not.
>
> if (-t STDIN && -t STDOUT) {
> print "Now what? ";
> }
>
> On POSIX systems, you can test whether your own process group matches
> the current process group of your controlling terminal as follows:
>
> use POSIX qw/getpgrp tcgetpgrp/;
>
[snip]
Another possibility, and sometimes a better one, is to let the
user tell you whether you're running interactively or not, for
example, by providing a "-i" or "--interactive" command-line option.
One benefit of this is that it makes it easier for the user to test
the non-interactive behavior of the program.
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Nokia
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
------------------------------
Date: Wed, 21 Oct 2009 06:45:43 -0500
From: brian d foy <brian.d.foy@gmail.com>
Subject: Re: FAQ 8.37 How do I find out if I'm running interactively or not?
Message-Id: <211020090645434036%brian.d.foy@gmail.com>
In article <lnzl7lw648.fsf@nuthaus.mib.org>, Keith Thompson
<kst-u@mib.org> wrote:
> PerlFAQ Server <brian@theperlreview.com> writes:
> [...]
> > 8.37: How do I find out if I'm running interactively or not?
> Another possibility, and sometimes a better one, is to let the
> user tell you whether you're running interactively or not, for
> example, by providing a "-i" or "--interactive" command-line option.
Most often you see that as the -q or --quiet options.
However, a lot of FAQ answers are trivial when the answer is "Just ask
the user!". The problem is that users can lie (and often do because the
programs don't supply a feature and need a workaround). Even if the
user says that the programming is running interactively, that still
doesn't mean the program is running interactively.
------------------------------
Date: Wed, 21 Oct 2009 20:58:24 +0000 (UTC)
From: Ilya Zakharevich <nospam-abuse@ilyaz.org>
Subject: Re: FAQ 8.37 How do I find out if I'm running interactively or not?
Message-Id: <slrnhdutfg.arc.nospam-abuse@chorin.math.berkeley.edu>
On 2009-10-21, brian d foy <brian.d.foy@gmail.com> wrote:
>> > 8.37: How do I find out if I'm running interactively or not?
>> Another possibility, and sometimes a better one, is to let the
>> user tell you whether you're running interactively or not, for
>> example, by providing a "-i" or "--interactive" command-line option.
> Most often you see that as the -q or --quiet options.
>
> However, a lot of FAQ answers are trivial when the answer is "Just ask
> the user!". The problem is that users can lie (and often do because the
> programs don't supply a feature and need a workaround). Even if the
> user says that the programming is running interactively, that still
> doesn't mean the program is running interactively.
Neither do any of the FAQ answers...
Given that it cannot be done programmatically, I think that the answer
should be modifed in the following way:
a) Point explicitly that FAQ answers are just heuristics - they
answer different questions. E.g., the user may want to pipe
their input through `tee'; [I expect that] the second test won't
even compile on non-POSIX systems (do not know what is a scenario
when user would like to insert a process leader between the
termininal and a program - I never manipulate process groups on
*NIX).
b) Put a suggestion to ask user to choose between two behaviours.
c) Mention which environment variables are expected to be set during
automatic testing.
Yours,
Ilya
------------------------------
Date: Wed, 21 Oct 2009 00:33:37 -0700
From: Keith Thompson <kst-u@mib.org>
Subject: Re: Getting current time in milliseconds
Message-Id: <ln4optxktq.fsf@nuthaus.mib.org>
Jürgen Exner <jurgenex@hotmail.com> writes:
> laredotornado <laredotornado@zipmail.com> wrote:
>>I'm on a Mac OS 10.5.6 with Perl 5.8.8. From a shell script (/bin/
>>sh), do you know how I could use perl to get the current time in
>>milliseconds (or microseconds)
>
> perldoc Time::HiRes
>
>> and store the value in a shell variable?
>
> That is impossible because child processes cannot alter variables of the
> parent process. See "perldoc -q env" for a possible workaround.
But a child process can certainly modify its own environment in
response to the output of something it invokes.
The workaround suggested in "perldoc -q env" requires the Perl script
to generate a shell command to be evaluated, but that's not necessary.
For example:
#!/bin/sh
curr_time=$(perl -e "...")
where the Perl command just prints the time.
Note that the older (and still supported) form of $(command) is
`command`. csh and tcsh support `command` but not $(command);
I don't know if any sh derivatives fail to support $(command).
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Nokia
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
------------------------------
Date: Wed, 21 Oct 2009 06:03:27 -0700
From: Jürgen Exner <jurgenex@hotmail.com>
Subject: Re: Getting current time in milliseconds
Message-Id: <h61ud5l99cnf8me1tghhugscf5e2ve1qqv@4ax.com>
Keith Thompson <kst-u@mib.org> wrote:
>Jürgen Exner <jurgenex@hotmail.com> writes:
>> laredotornado <laredotornado@zipmail.com> wrote:
>>>I'm on a Mac OS 10.5.6 with Perl 5.8.8. From a shell script (/bin/
>>>sh), do you know how I could use perl to get the current time in
>>>milliseconds (or microseconds)
>>
>> perldoc Time::HiRes
>>
>>> and store the value in a shell variable?
>>
>> That is impossible because child processes cannot alter variables of the
>> parent process. See "perldoc -q env" for a possible workaround.
>
>But a child process can certainly modify its own environment in
>response to the output of something it invokes.
But then it is acting as a new parent process, not as a child process.
If you want to split hairs, then I should rephrase my answer as:
>>> and store the value in a shell variable?
You set the value in the hash %ENV. But that doesn't do you any good
because it sets the value in the currently running Perl process, not in
the calling shell process. If you want to modify the value of the shell
variable in a parent process directly from the child process than it
cannot be done.
>The workaround suggested in "perldoc -q env" requires the Perl script
>to generate a shell command to be evaluated, but that's not necessary.
[example snipped]
True, but all of that is some magic on the shell side and applies to any
process called by the shell in any programming language and therefore
doesn't have anything to do with Perl and that's why the answer in the
Perl FAQ points you to the documentation and FAQ for whatever shell you
are using.
jue
------------------------------
Date: Wed, 21 Oct 2009 06:30:03 -0700 (PDT)
From: laredotornado <laredotornado@zipmail.com>
Subject: Re: Getting current time in milliseconds
Message-Id: <3b0c6ec4-d657-4418-9e13-2987be034fe5@x5g2000prf.googlegroups.com>
On Oct 20, 4:31=A0pm, Jim Gibson <jimsgib...@gmail.com> wrote:
> In article
> <c117c8d9-0749-4552-8e26-5188353a1...@o9g2000prg.googlegroups.com>,
>
> laredotornado<laredotorn...@zipmail.com> wrote:
> > Hi,
>
> > I'm on a Mac OS 10.5.6 with Perl 5.8.8. =A0From a shell script (/bin/
> > sh), do you know how I could use perl to get the current time in
> > milliseconds (or microseconds) and store the value in a shell
> > variable?
>
> % set t=3D`perl -MTime::HiRes=3Dgettimeofday -e 'print
> int(1000*gettimeofday()).qq(\n);'` ; echo Time in msec is $t
> Time in msec is 1256077820486
> %
>
> --
> Jim Gibson
Thanks, Jim. That's a winner! - Dave
------------------------------
Date: Wed, 21 Oct 2009 02:57:42 +0100
From: Ben Morrow <ben@morrow.me.uk>
Subject: Re: How would I do this in perl?
Message-Id: <md62r6-e36.ln1@osiris.mauzo.dyndns.org>
Quoth Ilya Zakharevich <nospam-abuse@ilyaz.org>:
> On 2009-10-20, Ben Morrow <ben@morrow.me.uk> wrote:
> > IIRC you were criticised for writing
> >
> > $_ =~ s///;
> >
> > which is redundant
>
> No way! (Unless you talk about 6 leftmost characters.)
Yes, I only meant that the '$_ =~' part was redundant. The s/// was just
a placeholder; I didn't realise people might think I was talking about
the special semantics of //.
Ben
------------------------------
Date: Wed, 21 Oct 2009 12:37:26 -0000
From: Justin C <justin.0908@purestblue.com>
Subject: Learning OO, object creation query.
Message-Id: <3e78.4adf0086.79e1a@zem>
I've been reading various OO tutorials and other references on the web
(I found <URL: http://www.perlmonks.org/?node_id=218778> more useful
than perlboot and perltoo - though they are more clear to me now). To
see if I'm understanding correctly I'm writing something that has little
use other than educating me.
I have a module:
package My_Product;
use strict;
sub new {
my $class = shift;
my $item = shift;
my $style = shift;
my $price = shift;
my @sizes = @_;
my $self = {
ITEM => $item,
STYLE => $style,
PRICE => $price,
SIZES => @sizes,
};
return bless $self, $class;
}
I'm creating a new object with:
my $item = MM_Product->new($fields[0], $fields[1], $fields[2], @sizes);
But when I later do
foreach my $size ($item->{SIZES}) {
...
}
I only get the first item of the array.
I know that there are several items in the array when it's passed to the
new object, but I don't know how to be sure that it arrived at the
object, and that, therefore, it's there when I want to access it.
Here's a working version of the program (if you create the above module
too) it's as short as I could make it.
#!/usr/bin/perl
use warnings;
use strict;
use My_Product;
my @items;
foreach (<DATA>) {
chomp;
my @fields = split /:/;
my $size_count = length $fields[3];
my @sizes;
for (my $i = 0; $i < $size_count; $i++) {
my $size = substr($fields[3], $i, 1);
push @sizes, $size;
}
my $item = My_Product->new($fields[0], $fields[1], $fields[2], @sizes);
push @items, $item;
}
foreach my $item (@items) {
foreach my $size ( $item->{SIZES} ) {
printf("%-4s %-20s %-20s %7.2f \n", $size, $item->{ITEM}, $item->{STYLE}, $item->{PRICE});
}
}
__DATA__
AVS1234:TS:6.99:678ABCD
DMBT007:HS:7.99:BCD
G12128C:TS:8.99:ABCD
Thank you for any help you can give with this.
Justin.
--
Justin C, by the sea.
------------------------------
Date: Wed, 21 Oct 2009 13:06:51 +0000 (UTC)
From: Willem <willem@stack.nl>
Subject: Re: Learning OO, object creation query.
Message-Id: <slrnhdu1rb.kof.willem@turtle.stack.nl>
Justin C wrote:
) I've been reading various OO tutorials and other references on the web
) (I found <URL: http://www.perlmonks.org/?node_id=218778> more useful
) than perlboot and perltoo - though they are more clear to me now). To
) see if I'm understanding correctly I'm writing something that has little
) use other than educating me.
Your problem has nothing to do with OO.
Here's a simple program that demonstrates the same problem:
sub foo {
my @sizes = @_;
my $hash = {
SIZES => @sizes,
};
return $hash;
}
my $hash = foo(1, 2, 3);
for my $item ($hash->{SIZES}) { print $item }
To find the answer to your problem, read up on references (perlreftut ?).
Simply put: you can't use an array as a value in a hash, and when you do it
will get expanded to a list.
Assuming: @sizes = (1, 2, 3)
This: { SIZES => @sizes }
Gets expanded to: { 'SIZES', 1, 2, 3 }
Or, equivalently: { SIZES => 1, 2 => 3 }
What you want is either: { SIZES => \@sizes } or: { SIZES => [@sizes] }
Be sure to read up on perldoc perlreftut and you'd also do good to read
some more about basic Perl.
SaSW, Willem
--
Disclaimer: I am in no way responsible for any of the statements
made in the above text. For all I know I might be
drugged or something..
No I'm not paranoid. You all think I'm paranoid, don't you !
#EOT
------------------------------
Date: Wed, 21 Oct 2009 17:02:26 +0200
From: "Dr.Ruud" <rvtol+usenet@xs4all.nl>
Subject: Re: Learning OO, object creation query.
Message-Id: <4adf2283$0$83251$e4fe514c@news.xs4all.nl>
Justin C wrote:
> I've been reading various OO tutorials and other references on the web
> (I found <URL: http://www.perlmonks.org/?node_id=218778> more useful
> than perlboot and perltoo - though they are more clear to me now). To
> see if I'm understanding correctly I'm writing something that has little
> use other than educating me.
>
> I have a module:
>
> package My_Product;
>
> use strict;
>
> sub new {
> my $class = shift;
> my $item = shift;
> my $style = shift;
> my $price = shift;
> my @sizes = @_;
> my $self = {
> ITEM => $item,
> STYLE => $style,
> PRICE => $price,
> SIZES => @sizes,
> };
> return bless $self, $class;
> }
The error is in "=> @sizes", you probably meant "=> \@sizes".
I would rather split a new() like that into a new() and an init().
$ cat My_Product.pm
package My_Product;
use strict;
use warnings;
our $VERSION = "1.00";
sub new {
my $class= shift;
my $self= bless {}, $class;
return $self->init(@_);
}
sub init {
my $self= shift;
$self->{ style }= shift;
$self->{ item }= shift;
$self->{ price }= shift;
$self->{ sizes }= [ @_ ];
return $self;
}
$ perl -MData::Dumper -MMy_Product -wle'
my $p= My_Product::->new("printed", "T-shirt", 42, "XXL", "M");
print Dumper($p);
$p->init("white", "paper", 42.1, "A4", "Letter");
print Dumper($p);
'
$VAR1 = bless( {
'item' => 'T-shirt',
'style' => 'printed',
'price' => 42,
'sizes' => [
'XXL',
'M'
]
}, 'My_Product' );
$VAR1 = bless( {
'item' => 'paper',
'style' => 'white',
'price' => '42.1',
'sizes' => [
'A4',
'Letter'
]
}, 'My_Product' );
Next step would be to let init take a hashref as parameter, and/or used
named parameters. Or just check out Moose.
--
Ruud
------------------------------
Date: Wed, 21 Oct 2009 15:49:51 -0000
From: Justin C <justin.0908@purestblue.com>
Subject: Re: Learning OO, object creation query.
Message-Id: <5445.4adf2d9f.a1118@zem>
On 2009-10-21, Dr.Ruud <rvtol+usenet@xs4all.nl> wrote:
>
> The error is in "=> @sizes", you probably meant "=> \@sizes".
Thank you, I have it working now.
> named parameters. Or just check out Moose.
I've just Googled that, I think I should really understand what I'm
doing before I put another layer between me and what I want to do. I'm
sure that, once I understand it, a tool like Moose will be useful... And
they have a TextMate bundle, so I'm half sold on the idea already!
Justin.
--
Justin C, by the sea.
------------------------------
Date: Wed, 21 Oct 2009 15:57:26 -0000
From: Justin C <justin.0908@purestblue.com>
Subject: Re: Learning OO, object creation query.
Message-Id: <54a6.4adf2f66.9b324@zem>
On 2009-10-21, Willem <willem@stack.nl> wrote:
> Justin C wrote:
> ) I've been reading various OO tutorials and other references on the web
> ) (I found <URL: http://www.perlmonks.org/?node_id=218778> more useful
> ) than perlboot and perltoo - though they are more clear to me now). To
> ) see if I'm understanding correctly I'm writing something that has little
> ) use other than educating me.
>
> Your problem has nothing to do with OO.
I realise that, but I didn't know how to represent my problem with
showing what I had done.
> Here's a simple program that demonstrates the same problem:
>
> sub foo {
> my @sizes = @_;
> my $hash = {
> SIZES => @sizes,
> };
> return $hash;
> }
> my $hash = foo(1, 2, 3);
> for my $item ($hash->{SIZES}) { print $item }
>
> To find the answer to your problem, read up on references (perlreftut ?).
Oh no, not again! That document *really* makes my brain hurt... though I
always seem to be a bit better off before each time I've read it (or
bits of it).
> Simply put: you can't use an array as a value in a hash, and when you do it
> will get expanded to a list.
I think my problem was not understanding what I was creating with the
object, now I see that it's a hash it all makes more sense.
> What you want is either: { SIZES => \@sizes } or: { SIZES => [@sizes] }
That's done the trick, thank you.
> Be sure to read up on perldoc perlreftut and you'd also do good to read
> some more about basic Perl.
The most read book I have ever owned is the Llama, though, in this
instance, I think the book may be too basic.
Thank you for your reply, you've helped clarify several points in my
mind.
Justin.
--
Justin C, by the sea.
------------------------------
Date: Wed, 21 Oct 2009 11:02:12 -0700
From: merlyn@stonehenge.com (Randal L. Schwartz)
To: justin.news@purestblue.com
Subject: Re: Learning OO, object creation query.
Message-Id: <868wf41v8b.fsf@blue.stonehenge.com>
>>>>> "Justin" == Justin C <justin.0908@purestblue.com> writes:
Justin> The most read book I have ever owned is the Llama, though, in this
Justin> instance, I think the book may be too basic.
Yes, you now need the Alpaca, the Llama sequel. It covers (surprise!)
references and objects, right where you need them.
print "Just another Perl hacker,"; # the original!
--
Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095
<merlyn@stonehenge.com> <URL:http://www.stonehenge.com/merlyn/>
Smalltalk/Perl/Unix consulting, Technical writing, Comedy, etc. etc.
See http://methodsandmessages.vox.com/ for Smalltalk and Seaside discussion
------------------------------
Date: Wed, 21 Oct 2009 17:17:03 -0400
From: sreservoir <sreservoir@gmail.com>
Subject: Re: prototypes
Message-Id: <hbntnu$kvu$1@aioe.org>
Ben Morrow wrote:
> Quoth sreservoir <sreservoir@gmail.com>:
>> Ben Morrow wrote:
>>> The assignment will give a warning, and that can trivially be replaced
>>> with a (more helpful) error with
>>>
>>> sub hpush (\%%) {
>>> @_ % 2 or croak "Odd number of elements in hpush";
>> that croak should be:
>> @_ % 2 and croak ...
>
> No it shouldn't.
>
>> @_ % 2 == 1 if @_ is odd, 0 if even.
>
> Yes...
>
> (think about it more carefully :))
Oh, yes, the \%. I was giving bad advice for a while yesterday. Maybe I
need to sleep more. :)
--
"Six by nine. Forty two."
"That's it. That's all there is."
"I always thought something was fundamentally wrong with the universe"
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
From: Perl-Users-Request@ruby.oce.orst.edu (Perl-Users-Digest Admin)
Subject: Digest Administrivia (Last modified: 6 Apr 01)
Message-Id: <null>
Administrivia:
To submit articles to comp.lang.perl.announce, send your article to
clpa@perl.com.
Back issues are available via anonymous ftp from
ftp://cil-www.oce.orst.edu/pub/perl/old-digests.
#For other requests pertaining to the digest, send mail to
#perl-users-request@ruby.oce.orst.edu. Do not waste your time or mine
#sending perl questions to the -request address, I don't have time to
#answer them even if I did know the answer.
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End of Perl-Users Digest V11 Issue 2645
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