Comparative Product Review:
HTMLPP (vs. PPWizard)


David Mertz, Ph.D.
Gnosis Software, Inc.
July 2000

At A Glance

Creators:      Pieter Hintjens <ph@imatix.com> and
               Enrique Bengoechea <ebb@eco.uc3m.es>
Price/License: Free of cost; source under GPL.
Home Page:     http://www.imatix.com/html/htmlpp/index.htm
Requirements:  System with Perl interpreter


What Is Htmlpp?

HTMLPP is a text "preprocessor" written in Perl. A preprocessor is a great thing to use when you want to generate a site worth of consistent-looking pages. Rather than having to copy-and-paste things like navigation bars, site-titles, color and background definitions, with a preprocessor you can give a simple name to a whole batch of HTML; and changing it in one place will change it everywhere.

What a preprocessor actually does is read a source file that consists of some literal text with some directives, and create output according to the directives. HTMLPP directives can be variable insertions, or one of the "intrinsic functions", or even Perl program fragments.

HTMLPP versus PPWizard

For Webreview readers who happened to see my review of PPWizard (http://webreview.com/pace/print/2000/06/30/feature/index03.html), my description of HTMLPP will sound awfully familiar. HTMLPP and PPWizard exist to fill nearly the same niche, and in many ways, what they both do is dictated by the niche. You might be tempted to decide between the two tools based just on you familiarity with Perl (HTMLPP) versus REXX (PPWizard), but I find that there are much more important differences between the tools than this. In using either tool, you will probably use the high-level macros more than you will the underlying scripting language; and either scripting language allows friendly ways of expressing program constructs.

In my PPWizard review, I contrasted a preprocessor with server-side includes and with server-side scripting. Those remarks apply just as well to HTMLPP as they did to PPWizard, so I will not repeat them here.

What is more interesting to look at is the difference in design philosophy of HTMLPP and PPWizard. One thing that stands out is that PPWizard is most facile at building up complex HTML documents from multiple templates and data sources. HTMLPP, on the other hand, is much more focussed on breaking down complex source documents into simpler groups of HTML pages (such as chapters of a document). Because of this differing focus, if your source is documents in a traditional book/journal/manual sense, HTMLPP is likely to serve you better. For that sort of thing, HTMLPP syntax feels more natural, and less intrusive. In futher support of the document model, HTMLPP offers a basic degree of multilingual support with a language directive (and language template files), along with simple table-of-contents directives. On the other hand, if you do not have a "source" in this documentary sense, but are building complex HTML "whole cloth", PPWizard is probably a better choice.

Intrinsic Functions

HTMLPP can call any Perl code that can be wrapped in an eval call. But most of the time it is easier to use one of the functions that HTMLPP provides for you. You don't necessarily have to be a Perl programmer to use HTMLPP intrinsic functions; you are less likely to make a programming error; and the syntax flows a little more naturally. Intrinsic functions include a number of functions for getting and calculating dates, some simple text transformation functions (like upper()), some functions to check on files, and quite usefully some functions to check image sizes. The results of these functions will normally be written into resultant HTML pages.

While HTMLPP has some of the most useful built-in functions you might think of, PPWizard simply has a lot more functions in it. Partially this is probably because PPWizard seems to be more actively maintained, but part is also because of PPWizards greater focus on complex conditional processing.

Guru Mode

In keeping with its focus on source documents, HTMLPP has a nice trick that PPWizard lacks (except in very rudimentary form). In the "guru mode", HTMLPP can process source files with no apparent markup at all. Guru mode looks for some features of text that look good as plain ASCII, and converts them to what it thinks is proper HTML. For example, headers (H1, H2, H3, respectively) should look like:

Chapter Header
**************

Section Header
==============

Subsection Header
-----------------

Some other formatting conventions allow you to indicate bullets, numbered lists, tables, images, and a few other things. As an unobtrusize way to prepare documents, these few "invisible" markup conventions are quite easy to learn and use. On this line, you also might find useful a utility I wrote that serves a similar purpose, called Txt2Html; find it at, <http://gnosis.cx/cgi/txt2html.cgi>. Txt2Html doesn't deal with quite as many formatting features as HTMLPP does, but it does a number of other things HTMLPP does not (and it is also free).

Overall

HTMLPP is a very quick way to get started with preprocessing, and all the site-development benefits that provides. Guru mode is good mojo; and even the full markup feels very light and comfortable to work with. For more powerful processing, PPWizard is a good step up, but either tool can be made to do whatever you want with a little work. After using tools like these, I can hardly imagine going back to trying to maintain consistent HTML pages through endless cutting-and-pasting. A preprocessor is a great way to save yourself some work.

About The Author

David Mertz enjoys writing programs to arrange words for him just about as much as he enjoys writing words himself. You can find out copious biographical details by rooting around at http://gnosis.cx/publish/.