Re: What name for a printer status supplies module?
On Dec 17, 2004, at 4:02 PM, David Landgren wrote:
The biggest problem I see is how to avoid having to sketch out
everything up front. I think it's only after I get 3 or 4
Printer::Status::x::y modules under my belt that I'll *begin* to get a
feel for where the divisions lie and what methods can be hoisted up
the namespace to Printer::Status::X or Printer::Status.
For instance, the older 4500 model had three cartridges: drum,
transfer and fuser. The new one only has two, they did away with the
drum. Not all models have the same consumables; two models may have
none in common. I'm not sure how to represent this elegantly. What I
do know is that I don't want to build up a towering hierarchy of
classes for something which is, at the end of day, really pretty
trivial.
If I were you I'd not use classes to model that part of it. Just have
a Printer::Status::HP4500 (or HP::HP4500 or whatever) object with a
components() or consumables() method that returns a hash mapping name
to properties. E.g.:
$stuff = $printer-consumables();
# $stuff is now:
{ drum = {
whatever you know about the drum
},
transfer = {
whatever you know about the transfer
},
fuser = {
whatever you know about the fuser
},
}
I think Perl's built-in ways of interrogating hashes should be
sufficient for what people will want to do with the information.
-Ken
Re: What name for a printer status supplies module?
David Landgren [EMAIL PROTECTED] writes: The fact that it uses http is incidental. If HP bothered to supply a half-decent MIB, SNMP would be a good alternative. What does MIB stand for?
Re: What name for a printer status supplies module?
On Sat, 18 Dec 2004, Terrence Brannon wrote: David Landgren [EMAIL PROTECTED] writes: The fact that it uses http is incidental. If HP bothered to supply a half-decent MIB, SNMP would be a good alternative. What does MIB stand for? Men In Black. ;) Oh, you mean the geek version... MIB stands for Management Information Base and encapsualtes an API within an SNMP context for a given type of device. Various RFC's have described this through various versions of SNMP: http://www.drunkandretired.com/snmp/ has some good links. -- /chris There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author)
Re: What name for a printer status supplies module?
--- Ken Williams [EMAIL PROTECTED] wrote: If I were you I'd not use classes to model that part of it. Just have a Printer::Status::HP4500 (or HP::HP4500 or whatever) object with a components() or consumables() method that returns a hash mapping name to properties. E.g.: If you say you're going to take Vienna, take Vienna. Napoleon In this case, if an OO interface is provided, it should be used. A hash mapping makes it very easy to mitsype (sic) the key names. It's more difficult to mistype method names and have it still work. If one doesn't want the overhead of creating a class just for the returned data, one call always use the excellent Hash::AsObject (http://search.cpan.org/~nkuitse/Hash-AsObject-0.05/) module. Cheers, Ovid = Silence is Evil http://users.easystreet.com/ovid/philosophy/decency.html Ovid http://www.perlmonks.org/index.pl?node_id=17000 Web Programming with Perl http://users.easystreet.com/ovid/cgi_course/
Re: What name for a printer status supplies module?
On Dec 18, 2004, at 12:26 PM, Ovid wrote:
--- Ken Williams [EMAIL PROTECTED] wrote:
If I were you I'd not use classes to model that part of it. Just
have
a Printer::Status::HP4500 (or HP::HP4500 or whatever) object with a
components() or consumables() method that returns a hash mapping name
to properties. E.g.:
If you say you're going to take Vienna, take Vienna.
Napoleon
In this case, if an OO interface is provided, it should be used. A
hash mapping makes it very easy to mitsype (sic) the key names. It's
more difficult to mistype method names and have it still work.
Yeah, but if the method interfaces are going to be different for
different printers (because they have different consumables), then
you're going to have to use if($status-can('toner')) etc. instead of
if(exists $status-{toner}) etc. I find the former weird in this case.
And how would you iterate over all the consumables of a printer? It's
going to take some extra design to cover the use cases.
-Ken
Re: What name for a printer status supplies module?
--- Ken Williams [EMAIL PROTECTED] wrote:
Yeah, but if the method interfaces are going to be different for
different printers (because they have different consumables), then
you're going to have to use if($status-can('toner')) etc. instead of
if(exists $status-{toner}) etc. I find the former weird in this
case.
if (exists $status-{toner}) {...}
That is not conceptually different from:
if ($status-exists('toner')) {...}
Which is a very small step from $status-can or UNIVERSAL::can($status,
...).
It sounds to me like the only difference of opinion is in the syntax,
not the merits of sanity checking. If so, it just falls back to the
original author to decide.
Cheers,
Ovid
=
Silence is Evil
http://users.easystreet.com/ovid/philosophy/decency.html
Ovid http://www.perlmonks.org/index.pl?node_id=17000
Web Programming with Perl http://users.easystreet.com/ovid/cgi_course/
Re: What name for a printer status supplies module?
Ovid wrote: --- Ken Williams [EMAIL PROTECTED] wrote: If I were you I'd not use classes to model that part of it. Just have a Printer::Status::HP4500 (or HP::HP4500 or whatever) object with a components() or consumables() method that returns a hash mapping name to properties. E.g.: If you say you're going to take Vienna, take Vienna. Napoleon In this case, if an OO interface is provided, it should be used. A hash mapping makes it very easy to mitsype (sic) the key names. It's more difficult to mistype method names and have it still work. If one doesn't want the overhead of creating a class just for the returned data, one call always use the excellent Hash::AsObject (http://search.cpan.org/~nkuitse/Hash-AsObject-0.05/) module. Oooh, I didn't know about that module. That's very nice actually, because a kit has quite a number of attributes, not just percent remaining. In fact, an HP 4600 kit doesn't even have that. What it does have is number of pages printed so far, number of estimated pages remaining, based on a historical page coverage of x%, serial number and a few other odds and ends. Hash-AsObject will remove a lot of the grunt work, thanks for the tip. David
What name for a printer status supplies module?
List, I have some code that queries an HP LaserJet 4600 printer to retrieve a web page, that I then scrape to pick out the values of the various consumables it has (CMYK cartridges and other kits). The fact that it uses http is incidental. If HP bothered to supply a half-decent MIB, SNMP would be a good alternative. Anyway, I now have to deal with other HP models, and Ricoh printer/copiers as well. And I haven't a clue what namespace to use. Your advice is much appreciated. Thanks, David
Re: What name for a printer status supplies module?
On Fri, 2004-12-17 at 21:21 +0100, David Landgren wrote: List, I have some code that queries an HP LaserJet 4600 printer to retrieve a web page, that I then scrape to pick out the values of the various consumables it has (CMYK cartridges and other kits). The fact that it uses http is incidental. If HP bothered to supply a half-decent MIB, SNMP would be a good alternative. Anyway, I now have to deal with other HP models, and Ricoh printer/copiers as well. And I haven't a clue what namespace to use. Your advice is much appreciated. Printer:: comes to mind. How about: Printer::Status::Brand::Model Brand could provide the a common interface around (and wrap) Model. And Status could provide the generic interface for printer status. Just some thoughts... Lincoln
