Re: RFC: Template::YetAnother
I've said it before... :)
http://mathforum.org/epigone/modperl/zhixswahar/v04210105b76eecf6c2be@%5b192.168.1.3%5d
Rob
On Sat, Nov 16, 2002 at 10:33:44PM +0100, Thomas Klausner wrote:
Hi!
On Sat, Nov 16, 2002 at 03:31:39PM -0500, Perrin Harkins wrote:
I also posted this on perlmonks:
http://www.perlmonks.org/index.pl?node_id=213300
Ovid on Perlmonks already said some of the things I would have said
about needing a presentation language. For a templating system to be
useful, it has to be able to deal with loops and conditionals. Your
system pushes those into the Perl code, splitting the presentation
control into multiple places. This fails one of my major goals: the
template coders should be able to change the presentation without help
from a Perl coder. What if they decide they don't want to loop through
the links, but rather just print a message saying there are some? What
if they only want to show the first two? What if they want to display a
list with commas between the elements where they didn't use a separator
before? A mature templating system can handle all of these issues
without changing the main Perl module code.
That's a very good point I didn't really think about. I was thinking
of templates as DUMB frontends that should just display
data. Period.
Thinking of them as tools that handle presentation logic (as Ovid
pointed out) seems to make more sense.
It does pay of to write RFCs before starting to code...
Because IMO, the main reason for using templates is to seperate code
from markup.
It sounds to me like you want one of the HTML attribute ones, like Petal
or HTML::Seamstress. What was wrong with those?
One problem I see with HTML::Seamstress is that it uses the HTML
attributes 'class' and 'id' for templating info. But those attributes
are used by CSS and JavaScript and might conflict somehow. I do not
know if you can change the behaviour of HTML::Seamstress to use other
attributes, though. But this stopped my from looking further.
And I didn't look at Petal. For now.
There is one module, CGI::FastTemplate, that does seperate code from
markup completly. But the way different templates are strung together
seems rather comlicated to me.
It's not complicated, but it is somewhat confusing the first time you
look at it. I don't find your approach much easier though.
Well, I found mine easier :-)
(But I guess this is the reason for the Template Flood on CPAN -
everbody finds his own solution easier...)
Isn't your fill method just doing a sort of multi-level join here? All
of the data is passed in already, so there is no reason to delay
evaluation of the templates.
The main reason for doing this was to simplify testing. I planned to
just test the plain data structures, that should be free of HTML at
this time (before the fill). This (testing) was in fact the reason I
started thinking about this proposal in the first place.
More importantly, your use of AUTOLOAD to treat method calls as file
names looks neat, but is not a good approach. It's limiting (all
templates in one directory!) and has potential security issues with
namespace clashes. These are all just the same method call with a
single argument changed, so why not write them that way?
I planned to handle those namespace and filename issues.
..
force you to use them. They are flexible modules. I think you should
look at them more closely before you go off on your own.
That's what I'll do. Thanks for the excellent feedback.
--
#!/usr/bin/perlhttp://domm.zsi.at
for(ref(bless[],just'another'perl'hacker)){s-:+-$-gprint$_.$/}
Re: RFC: Template::YetAnother
Thomas Klausner [EMAIL PROTECTED] writes: Yes, this is a RFC for Yet Another Templating System. I know that there are a lot of those around. But this own might be different/interesting (at least I think/hope so...) (...) One note: while talking about templating systems for generating HTML, it can be inspiring to take a look at the Zope Page Templates (yes, I know, this is the python/zope world, not perl...). They found the nice idea of injecting loops/ifs etc into HTML in the way which does not spoil HTML markup. Their introduction is on http://www.zope.org/Documentation/Articles/ZPT1 and reference is in http://www.zope.org/Documentation/Books/ZopeBook/current/AppendixC.stx Here are some examples (copied from the introduction) title tal:content=here/titlePage Title/title The URL is span tal:replace=request/URLURL/span. table border=1 width=100% tr th#/ththId/ththMeta-Type/ththTitle/th /tr tr tal:repeat=item container/objectValues td tal:content=repeat/item/number#/td td tal:content=item/idId/td td tal:content=item/meta_typeMeta-Type/td td tal:content=item/titleTitle/td /tr /table -- ( Marcin Kasperski | Osoba jest omegalizacj ewolucji uniwersalnej na ) ( http://www.mk.w.pl | okrelonym odcinku etapowym (Teilhard de Chardin) ) () ( Wygeneruj dokumentacj: http://www.mk.w.pl/narzedzia/narzedzia_gendoc )
Re: RFC: Template::YetAnother
Hi!
On Sat, Nov 16, 2002 at 10:43:44AM +0100, Marcin Kasperski wrote:
One note: while talking about templating systems for generating HTML,
it can be inspiring to take a look at the Zope Page Templates (yes, I
know, this is the python/zope world, not perl...). They found the nice
idea of injecting loops/ifs etc into HTML in the way which does not
spoil HTML markup.
There is a simmilar Perl implementation of this called HTML_Tree
http://homepage.mac.com/pauljlucas/software/html_tree/
A module based on HTML_Tree is on CPAN under the name of
HTML-Seamstress:
http://search.cpan.org/author/TBONE/HTML-Seamstress-1.17/Seamstress.pm
--
#!/usr/bin/perlhttp://domm.zsi.at
for(ref(bless[],just'another'perl'hacker)){s-:+-$-gprint$_.$/}
Re: RFC: Template::YetAnother
Hi!
On Fri, Nov 15, 2002 at 07:05:49PM -0800, Josh Chamas wrote:
Don't do it. If you want a stripped down version of
..
evolution of these things. The perl template user community is
already fractured enough,
I expected that canonical answer to all Template Proposals :-)
better to hop onto a project, hack it to your
satisfaction ( with the blessing of the maintainers ) to get
the configs/subclasses you need for your requirements.
I will take a closer look if my ideas could be implemented by
subclassing/extending Template Toolkit or CGI::FastTemplate.
But do you think that the concept sounds reasonable in the first
place?
--
#!/usr/bin/perlhttp://domm.zsi.at
for(ref(bless[],just'another'perl'hacker)){s-:+-$-gprint$_.$/}
Re: RFC: Template::YetAnother
Thomas Klausner wrote: Hi! On Sat, Nov 16, 2002 at 10:43:44AM +0100, Marcin Kasperski wrote: One note: while talking about templating systems for generating HTML, it can be inspiring to take a look at the Zope Page Templates (yes, I know, this is the python/zope world, not perl...). They found the nice idea of injecting loops/ifs etc into HTML in the way which does not spoil HTML markup. There is a simmilar Perl implementation of this called HTML_Tree http://homepage.mac.com/pauljlucas/software/html_tree/ A module based on HTML_Tree is on CPAN under the name of HTML-Seamstress: http://search.cpan.org/author/TBONE/HTML-Seamstress-1.17/Seamstress.pm There is also an implementation that copies the Zope style pretty closely called Petal: http://search.cpan.org/author/JHIVER/Petal-0.77/lib/Petal.pm - Perrin
Re: RFC: Template::YetAnother
Thomas Klausner wrote:
Yes, this is a RFC for Yet Another Templating System. I know that
there are a lot of those around. But this own might be
different/interesting (at least I think/hope so...)
I also posted this on perlmonks:
http://www.perlmonks.org/index.pl?node_id=213300
Ovid on Perlmonks already said some of the things I would have said
about needing a presentation language. For a templating system to be
useful, it has to be able to deal with loops and conditionals. Your
system pushes those into the Perl code, splitting the presentation
control into multiple places. This fails one of my major goals: the
template coders should be able to change the presentation without help
from a Perl coder. What if they decide they don't want to loop through
the links, but rather just print a message saying there are some? What
if they only want to show the first two? What if they want to display a
list with commas between the elements where they didn't use a separator
before? A mature templating system can handle all of these issues
without changing the main Perl module code.
Because IMO, the main reason for using templates is to seperate code
from markup.
It sounds to me like you want one of the HTML attribute ones, like Petal
or HTML::Seamstress. What was wrong with those?
There is one module, CGI::FastTemplate, that does seperate code from
markup completly. But the way different templates are strung together
seems rather comlicated to me.
It's not complicated, but it is somewhat confusing the first time you
look at it. I don't find your approach much easier though.
# generate a new template handler
my $th=Template::YetAnother-new
({
namespace='acme',
template_dir='/projects/acme/templates/',
});
# build up a data structure
$data={
title=$th-title('this is the title'),
breadcrumb=[
$th-link({url='/index.html',text='Home'}),
$th-separator_breadcrumb,
$th-link({url='/acme/index.html',text='Acme'}),
$th-separator_breadcrumb,
$th-link({url='/acme/bleach.html',text='Bleach'}),
],
content=[
$th-element({heading='SYNOPSIS',value='blabla'}),
$th-element({heading='DESCRIPTION',value='foo bar'}),
],
lastmod=scalar localtime,
};
# fill template print
print $th-fill({data=$data});
Isn't your fill method just doing a sort of multi-level join here? All
of the data is passed in already, so there is no reason to delay
evaluation of the templates.
More importantly, your use of AUTOLOAD to treat method calls as file
names looks neat, but is not a good approach. It's limiting (all
templates in one directory!) and has potential security issues with
namespace clashes. These are all just the same method call with a
single argument changed, so why not write them that way?
Here's the same thing written with Template Toolkit. You could use
HTML::Template, CGI::FastTemplate, Text::Template, etc. here with minor
changes:
my $th = Template-new({INCLUDE_PATH = '/projects/acme/templates/');
$th-process-('title.tmpl', {title = 'this is the title'});
$th-process-('link.tmpl', {url = '/index.html', text = 'Home'});
$th-process-('separator.tmpl');
$th-process-('link.tmpl', {url = '/index.html', text = 'Home'});
$th-process-('separator.tmpl');
$th-process-('link.tmpl', {url = '/acme/index.html', text = 'Acme'});
$th-process-('separator.tmpl');
... And so on.
Text::Template allows Perl code to be put in the template, and
HTML::Template/TT allow loops and conditionals, but no one is going to
force you to use them. They are flexible modules. I think you should
look at them more closely before you go off on your own.
- Perrin
Re: RFC: Template::YetAnother
Hi!
On Sat, Nov 16, 2002 at 03:31:39PM -0500, Perrin Harkins wrote:
I also posted this on perlmonks:
http://www.perlmonks.org/index.pl?node_id=213300
Ovid on Perlmonks already said some of the things I would have said
about needing a presentation language. For a templating system to be
useful, it has to be able to deal with loops and conditionals. Your
system pushes those into the Perl code, splitting the presentation
control into multiple places. This fails one of my major goals: the
template coders should be able to change the presentation without help
from a Perl coder. What if they decide they don't want to loop through
the links, but rather just print a message saying there are some? What
if they only want to show the first two? What if they want to display a
list with commas between the elements where they didn't use a separator
before? A mature templating system can handle all of these issues
without changing the main Perl module code.
That's a very good point I didn't really think about. I was thinking
of templates as DUMB frontends that should just display
data. Period.
Thinking of them as tools that handle presentation logic (as Ovid
pointed out) seems to make more sense.
It does pay of to write RFCs before starting to code...
Because IMO, the main reason for using templates is to seperate code
from markup.
It sounds to me like you want one of the HTML attribute ones, like Petal
or HTML::Seamstress. What was wrong with those?
One problem I see with HTML::Seamstress is that it uses the HTML
attributes 'class' and 'id' for templating info. But those attributes
are used by CSS and JavaScript and might conflict somehow. I do not
know if you can change the behaviour of HTML::Seamstress to use other
attributes, though. But this stopped my from looking further.
And I didn't look at Petal. For now.
There is one module, CGI::FastTemplate, that does seperate code from
markup completly. But the way different templates are strung together
seems rather comlicated to me.
It's not complicated, but it is somewhat confusing the first time you
look at it. I don't find your approach much easier though.
Well, I found mine easier :-)
(But I guess this is the reason for the Template Flood on CPAN -
everbody finds his own solution easier...)
Isn't your fill method just doing a sort of multi-level join here? All
of the data is passed in already, so there is no reason to delay
evaluation of the templates.
The main reason for doing this was to simplify testing. I planned to
just test the plain data structures, that should be free of HTML at
this time (before the fill). This (testing) was in fact the reason I
started thinking about this proposal in the first place.
More importantly, your use of AUTOLOAD to treat method calls as file
names looks neat, but is not a good approach. It's limiting (all
templates in one directory!) and has potential security issues with
namespace clashes. These are all just the same method call with a
single argument changed, so why not write them that way?
I planned to handle those namespace and filename issues.
..
force you to use them. They are flexible modules. I think you should
look at them more closely before you go off on your own.
That's what I'll do. Thanks for the excellent feedback.
--
#!/usr/bin/perlhttp://domm.zsi.at
for(ref(bless[],just'another'perl'hacker)){s-:+-$-gprint$_.$/}
Re: RFC: Template::YetAnother
Thomas Klausner wrote: Hi! Yes, this is a RFC for Yet Another Templating System. I know that there are a lot of those around. But this own might be different/interesting (at least I think/hope so...) I also posted this on perlmonks: http://www.perlmonks.org/index.pl?node_id=213300 So, here it is, in POD format: Don't do it. If you want a stripped down version of an existing templatting language, then that's great. Work with the authors of exising frameworks like Template Toolkit or HTML::Template that *were designed* as pure template frameworks ( as opposed to the app frameworks like Embperl, ASP, AxKit, Mason) I'm sure you can get the authors to accept patches to disable features that you don't want, you might even be able to create a subclass of such a template module that sets these for the end user, so if they just use Template:JustVarsPlease, and Template::JustVarsPlease is a subclass of Template or HTML::Template, then you have your solution. Those template solutions that are too much for you got that way because their users wanted needed more. That is the natural evolution of these things. The perl template user community is already fractured enough, better to hop onto a project, hack it to your satisfaction ( with the blessing of the maintainers ) to get the configs/subclasses you need for your requirements. That's what I would do anyway. :) Regards, Josh Josh Chamas, Founder phone:925-552-0128 Chamas Enterprises Inc.http://www.chamas.com NodeWorks Link Checkinghttp://www.nodeworks.com
