[Zope] Comments? To create products with Python or with ZClasses

[Kevin Dangoor]

Hi,

Please correct me if any assumptions in here are wrong. (You may not agree
with my conclusions, but as long as my assumptions are correct, I'm happy.
:)

Any other feedback is also welcomed, of course.

This document is also here:
http://www.zope.org/Members/tazzzzz/PythonOrZClass

Kevin
http://www.byproducts.com - Humor and Novelties


Purpose of this document

  May 5, 2000. Please send feedback!

  Zope offers two distinctly different development
  "environments": Python Products, and built through
  the web ZClasses. Though you can certainly use both in a
  single project, you will likely turn to one or the other
  as a first step when approaching a new problem. I get the
  feeling that the folks at DC turn to Python first, whereas
  I turn to ZClasses.

  This document doesn't go into any background about what a
  ZClass or Python Product is... I think other docs do that
  well enough. For the sake of brevity, I'll refer to
  Python Products as "PyProds".

Speed

  I believe that PyProds and ZClasses are roughly the same in
  terms of speed of execution. ZClasses have some wrapper stuff
  around them, but I don't think there is much (if any) extra code
  that needs to be executed when calling ZClass methods.

Development Tools

  PyProds are clearly at an advantage in terms of development
  tools. Creating ZClasses and propertysheets, and adding views
  and methods to a ZClass are certainly very user friendly
  processes. However, editing code in a textarea has some definite
  drawbacks. Since PyProds reside in the filesystem, it is very
  easy to use your favorite editor, CVS, grep and other tools when
  working with your code.

  ZClasses will be getting help down the line in the form of
  the ZopeStudio Mozilla app. Currently, you can edit your code
  using your favorite editor if it supports FTP. It also seems
  possible to create some simple tools that allow you to edit your
  ZClass code locally, store it in CVS, and send the changes through
  via XML-RPC or ZClient.

Flexibility

  PyProds win in the flexibility department as well. In order to keep
  evil people from gaining access to your box through your website,
  through the web components can only do a subset of what Python can
  do. For example, you can't open files in DTML or a PythonMethod.
  PyProds live in the file system, and therefore have access to
  all Python and Zope services. It is also likely to be a lot faster
  to create a relatively complex object hierarchy in Python than
  it would be to build it up through the web.

  A very important flexibility issue with ZClasses is that once you've
  created the ZClass, there is no guaranteed way to change the base
  classes. There are apparently some really deep issues behind this.
  To give yourself the ability to change base classes later on, it is
  probably wise to create a Python base class for your ZClass and have
  that class inherit from the appropriate other classes. Then, you can
  just change that little bit of Python in order to add or remove a base
  class. This has the added benefit that you can easily make minor
  additions to your ZClass that would not be possible through the web
  (such as writing a custom object traversal handler).

Ease of Programming

  Once you get into the swing of it, ZClasses are quite easy. Writing
  complicated DTML Methods is not necessarily a fun thing, but
  PythonMethods give you a way to avoid complicated DTML and still
  develop through the web.

  The single biggest reason that I don't develop my products in
  Python is the fact that you need to restart Zope to test your
  changes. For that reason, it is probably best to test your classes
  directly from the Python interpreter rather than through Zope.
  This allows you to see the changes much more quickly. Once you think
  your classes are basically working, you can fire up Zope and try
  it from the web.

  While that method certainly will get the job done, I find
  programming with ZClasses to be a nice fast process. You can
  have two browser windows going, one with the code and one
  where you're testing the code. The process of making a change
  and trying it out is very fast.

  I also find that Versions are very nice for minor bug repair
  on a production system.

Conclusions

  Python is a great language, but I think I'll stick to
  ZClasses for the bulk of my web development. They really are
  quite fast and easy, and PythonMethods give you the benefit of
  using a nice, clean language for your logic as well.

  I am going to start using Python base classes for my ZClasses
  though. It is really a very small amount of work to create them,
  and the benefits are significant: you can easily change base
  classes and create functionality that is otherwise impossible
  through the web.