=head1 NAME HTML::Seamstress::Quickstart - A gentle introduction to HTML::Seamstress =head1 Introduction This guide is designed to get you started with dynamically generating and modifying ("templating") HTML with L. We will work through several examples, with each one increasing your ability to work with Seamstress effectively. =head2 Sample files All the files for the samples are in the directory F =head1 Pure TreeBuilder Welcome to the first example. This is our bare-bones example. Let's say we want to dynamically modify the following HTML: pod_code 'Quickstart/html/greeting.html' Let's not use Seamstress at all in this case. Remember Seamstress just makes using L more convenient when writing software - it is completely optional and totally non-magical. So here's the (admittedly verbose) pure TreeBuilder solution: pod_code 'Quickstart/greeting-treebuilder.pl' There's a convenience function in L which makes it easy to replace all the content of an element. This will make our script shorter. If we simply use Seamstress, its C method will bless the HTML tree into a class which inherits from HTML::Element::Library, making it easy for us to shorten our program. So let's rework the example using bare-bones Seamstress. =head1 Base bones Seamstress rework Since we used HTML::Seamstress instead of HTML::TreeBuilder, our C<$tree> was blessed as an instance of C. Since C inherits from C and C, we have a C<$tree> which can use the methods of both. We will take advantage of the C method in L to shorten our program: pod_code 'Quickstart/greeting-seamstress-pure.pl' Now of course, this program is just itching to not repeat itself, so we will clean it up just a tad: pod_code 'Quickstart/greeting-seamstress-pure-mapped.pl' =head1 Abstract the file and our operations on it into a Perl LOOM Ok sweet, we have a nice tight program. But is this really application-level code? As the user of ultra-scaffolded frameworks such as L and L, I can say no. Our inline code must be much tighter. It must do no more than C, C, and C whatever C may be in this case. The key abstraction technique of the uber-modules is a package. Normally a package collects together a set of methods. In our case, it is collecting together an HTML file and the object-oriented operations on it. B from this point forward, a Perl class abstracting a file and tree operations on the file will be called a I - (L)ibrary (O)f (O)bject-oriented (M)ethods for HTML files. On the whole, there are two ways to build a C. The quick and dirty way is to stick a F<.pm> file in the same directory as the html file. This is fine for most purposes and is what I like to use. However in some cases it is not desirable or possible for the HTML and Perl to be in the same directory. This is the non quick and dirty approach. There are two ways to be squeaky clean as of this writing: =over =item 1 Provide an absolute path to the HTML We will demonstrate this approach =item 2 Inline the HTML There is no Seamstress API or utility support for this. But it is an idea and I just wanted to mention it for completeness. You can create a F<.pm> with the HTML along the lines of this. package html::hello_world; sub new {...} sub process {...} __HTML__ ... ... And then you could use L to read it in and submit an appropriate C method to do the proper blessings. But I don't like this approach. It makes it hard to stay synchronized with the designer as he continually makes updates. =back =head2 Quick and dirty LOOM building: .pm and .html in same directory We have an C module like this: pod_code 'Quickstart/html/Greeting.pm' which we make nice tight application-level use of like this: pod_code 'Quickstart/callGreeting.pl' =head3 Cleaning up our Perl class We are flowing smoothly now with nice tight code in our application. But should we be happy with this module? I see a few drawbacks which require improvement: =over =item * our file name is given as a relative path name Relative paths are fine as long as we are certain to start in the same directory, but we cannot be sure of that when building applications, so we need an absolute path. =item * we had to manually create this package =back Let's fix the first problem first. =head3 Make path to HTML file absolute Again, Seamstress just happens to have a subroutine which guesses the name of the HTML file associated with a Seamstress-style Perl module. It is called C and here we see it in use to give us the path to our file in absolute fashion: pod_code 'Quickstart/html/GreetingAbs.pm' and main code body is still the same: pod_code 'Quickstart/callGreetingAbs.pl' =head2 Slow and clean LOOM building: .pm and .html in different directory Here we need to slip a class in between C and our LOOM: pod_code 'Quickstart/lib/HTML/Seamstress/Base.pm' This class will make it easy to track down the directory of our HTML files. The LOOM class inherits from it and makes use of it in its constructor: pod_code 'Quickstart/lib/html/Greeting.pm' And out main body code is just as tight. We have a few statements to make sure to use the right version of C, but other than that, no changes: pod_code 'Quickstart/slowClean.pl' =head1 Automated creation of Seamstress-style packages Instead of manually creating or copying and pasting packages to create Seamstress-style packages, the F script in the Seamstress was off use. It is designed to help build the slow-clean LOOMs not the quick-and-dirty ones.... it really should be updated to support either usage mode. =head1 Use subroutines and Params::Validate to "componentize" your operations The final phase in Seamstress best practices is to break each tree manipulation down into a separate subroutine whose parameters are specified by L. If you do this, then you can control the dynamic HTML generation by parameterizing your subs properly. This advice will make more sense as you do more complex things with Seamstress Now you're ready for the big time! Have fun! =head1 COPYRIGHT AND LICENSE Copyright 2002-2006 by Terrence Brannon. This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself. =cut