From oliver.gorwits at oucs.ox.ac.uk  Thu Jul  5 10:12:48 2007
From: oliver.gorwits at oucs.ox.ac.uk (Oliver Gorwits)
Date: Thu, 05 Jul 2007 18:12:48 +0100
Subject: Module setup argument validation
Message-ID: <468D2690.2070304@oucs.ox.ac.uk>

Hi folks,

I'm writing a module which is essentially a blob of glue between some 
other very useful Perl modules.

What I'd like to do is validate the parameters coming in to my module, 
some of which are for my own use, and others are destined for the other 
modules (encapsulated as hashes).

I'm currently looking at Params::Validate -- but my question is, are 
there any other contenders in the ring?

Things I require are type checking (scalar, hashref, etc), setting of 
defaults for missing options, and ideally, overriding of options to 
enforced values.

thanks in advance,
oliver.
-- 
Oliver Gorwits, Network Infrastructure Group,
Oxford University Computing Services

From nik at ngo.org.uk  Thu Jul  5 15:53:28 2007
From: nik at ngo.org.uk (Nik Clayton)
Date: Thu, 05 Jul 2007 23:53:28 +0100
Subject: Module setup argument validation
In-Reply-To: <468D2690.2070304@oucs.ox.ac.uk>
References: <468D2690.2070304@oucs.ox.ac.uk>
Message-ID: <468D7668.3090100@ngo.org.uk>

Oliver Gorwits wrote:
> I'm writing a module which is essentially a blob of glue between some 
> other very useful Perl modules.
> 
> What I'd like to do is validate the parameters coming in to my module, 
> some of which are for my own use, and others are destined for the other 
> modules (encapsulated as hashes).
> 
> I'm currently looking at Params::Validate -- but my question is, are 
> there any other contenders in the ring?

There seem to be quite a few.  I note on CPAN:

     Params::Check (and Params::Check::Faster (!))
     Params::Util
     Params::Validate::Micro

If I wasn't going to use Params::Validate I would probably use 
Params::Util -- that's based solely on the author's reputation though.

I wrote about using Params::Validate a while back, 
http://jc.ngo.org.uk/blog/2007/01/15/perl-parameter-validation-and-error-handling/ 
might be helpful.

N

From nbowden at dsl.pipex.com  Fri Jul  6 01:50:04 2007
From: nbowden at dsl.pipex.com (Nigel Bowden)
Date: Fri, 6 Jul 2007 09:50:04 +0100
Subject: Module setup argument validation
References: <468D2690.2070304@oucs.ox.ac.uk> <468D7668.3090100@ngo.org.uk>
Message-ID: <001301c7bfaa$a63d76e0$0201010a@kcom.com>

Nik,

very nice article.

Nigel.

----- Original Message ----- 
From: "Nik Clayton" <nik at ngo.org.uk>
To: "Oliver Gorwits" <oliver.gorwits at oucs.ox.ac.uk>
Cc: "Milton Keynes Perl Mongers" <miltonkeynes-pm at pm.org>
Sent: Thursday, July 05, 2007 11:53 PM
Subject: Re: Module setup argument validation


> Oliver Gorwits wrote:
>> I'm writing a module which is essentially a blob of glue between some
>> other very useful Perl modules.
>>
>> What I'd like to do is validate the parameters coming in to my module,
>> some of which are for my own use, and others are destined for the other
>> modules (encapsulated as hashes).
>>
>> I'm currently looking at Params::Validate -- but my question is, are
>> there any other contenders in the ring?
>
> There seem to be quite a few.  I note on CPAN:
>
>     Params::Check (and Params::Check::Faster (!))
>     Params::Util
>     Params::Validate::Micro
>
> If I wasn't going to use Params::Validate I would probably use
> Params::Util -- that's based solely on the author's reputation though.
>
> I wrote about using Params::Validate a while back,
> http://jc.ngo.org.uk/blog/2007/01/15/perl-parameter-validation-and-error-handling/
> might be helpful.
>
> N
> _______________________________________________
> MiltonKeynes-pm mailing list
> MiltonKeynes-pm at pm.org
> http://mail.pm.org/mailman/listinfo/miltonkeynes-pm 


From oliver.gorwits at oucs.ox.ac.uk  Fri Jul  6 07:29:10 2007
From: oliver.gorwits at oucs.ox.ac.uk (Oliver Gorwits)
Date: Fri, 06 Jul 2007 15:29:10 +0100
Subject: Module setup argument validation
In-Reply-To: <468D7668.3090100@ngo.org.uk>
References: <468D2690.2070304@oucs.ox.ac.uk> <468D7668.3090100@ngo.org.uk>
Message-ID: <468E51B6.80203@oucs.ox.ac.uk>


Nik Clayton wrote:
> I wrote about using Params::Validate a while back,

Excellent, many thanks. Having looked at the alternatives you suggest, I 
am going to stick with Params::Validate and Exception::Class after all 
because they best fit my needs.

I'd already written some code with them on the hunch anyway, having 
needed to factor out some custom validating code from someone's library 
which I'm preparing for the CPAN.

By the way, I'm glad I posted to the list. Usually I would have just 
pestered poor old Tom and the others on IRC[1] but this time around he 
wisely suggested I email the list instead :-)

cheers,
oliver.
[1] #miltonkeynes at irc.perl.org
-- 
Oliver Gorwits, Network Infrastructure Group,
Oxford University Computing Services

From peter at dragonstaff.com  Thu Jul 12 08:41:44 2007
From: peter at dragonstaff.com (Peter Edwards)
Date: Thu, 12 Jul 2007 16:41:44 +0100
Subject: FW: Exeter University - Open Source community survey
Message-ID: <003b01c7c49b$44930810$0501a8c0@DRAGON1>

Maybe of interest to any guinea pigs out there  :)

Cheers, Peter
Dragonstaff Limited  http://www.dragonstaff.com  Business IT Consultancy

-----Original Message-----
From: A.Rabinovich at exeter.ac.uk [mailto:A.Rabinovich at exeter.ac.uk] 
Sent: 12 July 2007 15:54
To: peterdragon at users.sourceforge.net
Subject: Exeter University - Open Source community survey

Dear Peter,

We are contacting you because of your contributions to the Open Source 
community. We are social psychologists from the University of Exeter 
studying the structure and functioning of the OS movement. We are 
interested in the movement not just from our personal perspectives, but as 
a social phenomenon. OS does not appear to make much sense economically. So 
why does it work?

We would like to invite you to participate in an online survey (OS-based) 
that will take you about 15 minutes to complete. The survey explores 
several potential reasons why the OS movement is such a success. Among 
others, it seeks your opinion about the "OS ideology." Recently there have 
been discussions on OS forums and blogs about this ideology: some people 
think that it is something that keeps the movement going, others believe 
that ideology is immaterial to OS success. We are interested in your 
opinion and in the role that ideology plays in the success of the OS 
movement.
We also ask your opinions about a range of other factors which might be 
involved. As social psychologists, we are interested to know what 
importance the OS movement members attach to this community and how this 
affects intentions to contribute towards projects.

We would be grateful if you could spare 15 minutes of your time to 
participate. The survey can be found here:
http://psy.ex.ac.uk/~ar216/survey/index.php?sid=11

Please feel free to forward this link to other members of the OS community. 
If you have any questions or comments about the survey, we will be happy to 
answer them; please write to Prof. Tom Postmes (T.Postmes at ex.ac.uk) or Anna 
Rabinovich (a.rabinovich at ex.ac.uk).

 Yours sincerely,
Prof. Tom Postmes
Anna Rabinovich


From ziya at suzen.net  Sun Jul 15 03:08:10 2007
From: ziya at suzen.net (Ziya Suzen)
Date: Sun, 15 Jul 2007 11:08:10 +0100
Subject: use Aspect? (was: Module setup argument validation)
Message-ID: <7e7471f80707150308pdfa7e7csa3bd43c3b9e05291@mail.gmail.com>

Hi there

Just realized! did not send this to the group. It's kind of late now,
so let's change the thread:

Anyone using Aspect (see message below)? Any good for production use?

cheers
-z

---------- Forwarded message ----------
From: Ziya Suzen <ziya at suzen.net>
Date: Jul 6, 2007 2:21 PM
Subject: Re: Module setup argument validation
To: Nik Clayton <nik at ngo.org.uk>


On 7/5/07, Nik Clayton <nik at ngo.org.uk> wrote:
> Oliver Gorwits wrote:
> > I'm currently looking at Params::Validate -- but my question is, are

FWIW, I used this one in a few projects. I think it is the most
popular one, but I found that my code became very messy very quickly,
trying to check all the calls. It should probably be enough to use it
on the modules api methods only.

>
> There seem to be quite a few.  I note on CPAN:
>
>      Params::Check (and Params::Check::Faster (!))
>      Params::Util
>      Params::Validate::Micro

Checking the parameters is important but it seems like they are all
creating a lot of noise in the code (Although a lot better than doing
it by hand, I suppose).

A little out side of the topic, but has anyone used Aspect seriously?

Maybe checking the parameters using something like this is cleaner? Better?

 package YoungPerson;

 sub age {
   my $self = shift;
   my $age = shift;
   # do something useful
 }

 sub name    { ... }
 sub address { ... }

 package main;

 use Aspect;

 before {
   my $context = shift;
   die "error" if $context->params->[1] > 150;
   # call stack is different, so it might be little confusing actually
 } call 'YoungPerson::age';

It is a trivial example, but imagine that with a few subs and a few
params each with complicated validation rules and so on... you get the
picture.

BTW, I am not suggesting to use it. I don't know enough about Aspect
(performance?, reliability? debugging? war stories? ...). But looks
like a good solution to me. I though I'd mention it.

> I wrote about using Params::Validate a while back,
> http://jc.ngo.org.uk/blog/2007/01/15/perl-parameter-validation-and-error-handling/

Nice one. Thank you.

Cheers

--Ziya

From tom at eborcom.com  Tue Jul 17 00:27:34 2007
From: tom at eborcom.com (Tom Hukins)
Date: Tue, 17 Jul 2007 08:27:34 +0100
Subject: Meeting: Tuesday 24th July 2007
Message-ID: <20070717072733.GA68359@eborcom.com>

At last:  I've managed to announce a meeting with plenty of warning
before it happens.

Join us for the monthly Milton Keynes Linux and Perl social meeting.
The topics of conversation vary, so if you write, use or think about
any sort of open source software you might find it interesting.  If
you don't, there will be beer and you're still welcome to come along.

As usual, we will meet at the Wetherspoon's near the railway station
(not the one in the snow dome):
http://miltonkeynes.openguides.org/?J.D_Wetherspoon%2C_Central_Milton_Keynes

I'll be there from around 8pm, but you should arrive and leave
whenever suits you - people usually come and go throughout the
evening.  A few of us usually eat at the pub.

If you're worried you might not spot us, please ask off-list for my             
mobile number.  Don't look for the infamous laminated penguins:
they've disappeared.

See next week,
Tom

From tom at eborcom.com  Tue Jul 17 00:46:00 2007
From: tom at eborcom.com (Tom Hukins)
Date: Tue, 17 Jul 2007 08:46:00 +0100
Subject: use Aspect? (was: Module setup argument validation)
In-Reply-To: <7e7471f80707150308pdfa7e7csa3bd43c3b9e05291@mail.gmail.com>
References: <7e7471f80707150308pdfa7e7csa3bd43c3b9e05291@mail.gmail.com>
Message-ID: <20070717074600.GB68359@eborcom.com>

Hi, Ziya.

I like your idea of using Aspect to validate input: it fits well with
AOP's emphasis on separation of concerns.  I guess you could also use
after {} to assert that you produce the expected output.

I've used Aspect.pm quite a bit for analysing how code works (see my
slides: http://miltonkeynes.pm.org/talks/2006/10/learned_at_yapc.pdf)
but I've never used it in production.  The module itself doesn't do
anything too scary, but relies on Hook::LexWrap for its cleverness, so
any concerns about reliability and performance should focus on this.

Several people asked me after my talk how well Aspect would cope with
production code.  I don't know, as I've not tried it, but some people
seemed to think it would slow things down significantly.  I guess
Benchmark will tell you how it performs with your existing code.

You might also want to take a look at Sub::Override, or mess with
%Your::Module:: manually if you feel especially brave:
  use YAML;
  use Your::Module;
  print Dump %Your::Module::;

Good luck:  let us know how you get on.

Tom

From peter at dragonstaff.com  Tue Jul 17 02:22:08 2007
From: peter at dragonstaff.com (Peter Edwards)
Date: Tue, 17 Jul 2007 10:22:08 +0100
Subject: use Aspect? (was: Module setup argument validation)
In-Reply-To: <20070717074600.GB68359@eborcom.com>
References: <7e7471f80707150308pdfa7e7csa3bd43c3b9e05291@mail.gmail.com>
	<20070717074600.GB68359@eborcom.com>
Message-ID: <007c01c7c853$f87d4af0$2f00a8c0@DRAGON1>


>You might also want to take a look at Sub::Override, or mess with
>%Your::Module:: manually if you feel especially brave:
>  use YAML;
>  use Your::Module;
>  print Dump %Your::Module::;

I just searched on CPAN for Your::Module ... Doh!



From tom at eborcom.com  Tue Jul 17 02:47:02 2007
From: tom at eborcom.com (Tom Hukins)
Date: Tue, 17 Jul 2007 10:47:02 +0100
Subject: General Confusion (was: use Aspect?)
In-Reply-To: <007c01c7c853$f87d4af0$2f00a8c0@DRAGON1>
References: <7e7471f80707150308pdfa7e7csa3bd43c3b9e05291@mail.gmail.com>
	<20070717074600.GB68359@eborcom.com>
	<007c01c7c853$f87d4af0$2f00a8c0@DRAGON1>
Message-ID: <20070717094702.GA69837@eborcom.com>

On Tue, Jul 17, 2007 at 10:22:08AM +0100, Peter Edwards wrote:
> I just searched on CPAN for Your::Module ... Doh!

Don't worry, it's not as daft as announcing a meeting on a date that
doesn't conform to our rules.  I don't want to confuse people further
by rearranging the date, so let's pretend that July has 30 days.

Tom

From ziya at suzen.net  Tue Jul 17 04:58:59 2007
From: ziya at suzen.net (Ziya Suzen)
Date: Tue, 17 Jul 2007 12:58:59 +0100
Subject: use Aspect? (was: Module setup argument validation)
In-Reply-To: <20070717074600.GB68359@eborcom.com>
References: <7e7471f80707150308pdfa7e7csa3bd43c3b9e05291@mail.gmail.com>
	<20070717074600.GB68359@eborcom.com>
Message-ID: <7e7471f80707170458o73ccb39brc1be770834348629@mail.gmail.com>

On 7/17/07, Tom Hukins <tom at eborcom.com> wrote:
> I like your idea of using Aspect to validate input: it fits well with

Actually just saw Class::Container. As far as I can tell it separates
parameter validation (and more) in your code quite well. The down/up
side is you need to treat most of the things as objects, as far as I
can tell.

As far as I know (correct me anyone, if this is wrong)
Class::Container extracted from the same project (HTML::Mason) which
created Exception::Class and Params::Validate as well. It seems to be
using Params::Validate behind the curtain as well.

> AOP's emphasis on separation of concerns.  I guess you could also use
> after {} to assert that you produce the expected output.

Very nice. It becomes a bit like a 'contract', doesn't it?

> I've used Aspect.pm quite a bit for analysing how code works (see my
> slides: http://miltonkeynes.pm.org/talks/2006/10/learned_at_yapc.pdf)

I think you mean this:
http://miltonkeynes.pm.org/talks/2006/06/tom_hukins_tracing_aspect.pdf

Good one. Thank you.

> Good luck:  let us know how you get on.

Mine is just an experiment for now. AOP is sure a very interesting
topic and I have been looking into opportunities to use it for quite a
while now. But I suppose I am not 100% sold on the idea just yet.
Things like exception handling, stack traces, performance and so on
and most of all using it in a team still concerns me a lot.

In one of the problems I considered using Aspect.pm was with a big .pm
file. There is this huge piece of .pm file in my hand and it's been
growing day by day (Tom, you know what I am talking about). I have
considered AOP and other approaches to move some of the stuff out of
it. But the methods are sooooo huge as well, nothing seemed to make
sense.

So, I ended up slightly extending/changing your approach (clever
subclassing at creation) and adding 'hook' methods  (instead of
'$obj->can($method)' checks) here and there and use them from
subclasses.

Cheers

--Ziya

From zen35638 at zen.co.uk  Tue Jul 17 05:25:30 2007
From: zen35638 at zen.co.uk (Rod Norfor)
Date: Tue, 17 Jul 2007 13:25:30 +0100
Subject: General Confusion (was: use Aspect?)
In-Reply-To: <20070717094702.GA69837@eborcom.com>
References: <7e7471f80707150308pdfa7e7csa3bd43c3b9e05291@mail.gmail.com>
	<20070717074600.GB68359@eborcom.com>
	<007c01c7c853$f87d4af0$2f00a8c0@DRAGON1>
	<20070717094702.GA69837@eborcom.com>
Message-ID: <AF325DA7-BDAD-40F8-808E-CC2CCA39CAE6@zen.co.uk>


On 17 Jul 2007, at 10:47, Tom Hukins wrote:

> On Tue, Jul 17, 2007 at 10:22:08AM +0100, Peter Edwards wrote:
>> I just searched on CPAN for Your::Module ... Doh!
>
> Don't worry, it's not as daft as announcing a meeting on a date that
> doesn't conform to our rules.  I don't want to confuse people further
> by rearranging the date, so let's pretend that July has 30 days.
>

I didn't want to mention anything, just thought it was probably to do  
with some people visiting vienna... but that's not until next  
month.... confusion reigns.....

Of course the meeting is probably cursed, as normally happens when we  
change dates...

cheers.

Rod



> Tom
> _______________________________________________
> MiltonKeynes-pm mailing list
> MiltonKeynes-pm at pm.org
> http://mail.pm.org/mailman/listinfo/miltonkeynes-pm


From tom at eborcom.com  Mon Jul 23 04:48:57 2007
From: tom at eborcom.com (Tom Hukins)
Date: Mon, 23 Jul 2007 12:48:57 +0100
Subject: Meeting: Tuesday 24th July 2007
In-Reply-To: <20070717072733.GA68359@eborcom.com>
References: <20070717072733.GA68359@eborcom.com>
Message-ID: <20070723114857.GA57459@eborcom.com>

Hi all,

I thought I should send a quick reminder that we're meeting tomorrow,
on Tuesday 24th:
http://mail.pm.org/pipermail/miltonkeynes-pm/2007-July/000261.html

We're not meeting on the 31st as you might have expected.

See you soon,
Tom

From peter at dragonstaff.com  Thu Jul 26 17:17:02 2007
From: peter at dragonstaff.com (Peter Edwards)
Date: Fri, 27 Jul 2007 01:17:02 +0100
Subject: YAPC::EU 2007 in Vienna
Message-ID: <002001c7cfe3$9808d530$6501a8c0@DRAGON1>

I?ve booked my conference ticket, travel and accommodation for YAPC::EU in
Vienna

Going from Heathrow (LHR) Monday 27th August on BA0704 at 14:55 to Vienna
(VIE), returning on BA0701 Thursday 30th August at 14:15.
Staying at the Levante Parliament
http://vienna.yapceurope.org/ye2007/wiki?node=StayingAtLevanteParliament

Regards, Peter
Dragonstaff Limited  http://www.dragonstaff.com  Business IT Consultancy?