Question

Websites like WordPress and Tumblr allow designers to create themes that users can select. In general how would you architect a website to be flexible enough to allow custom themes for users?

Answer 1

Take a look on how Django does it. Django uses a Model-View-Controller-like approach in which you use views to populate a context, and then use that context to process a template. Note that Django has its own MVC terminology.

For example, if we say that our context reads as follows (in pseudo code),

author = 'mntnoe'
title = 'My Title'
content = '<p>This is my content</p>'

we could use the following template:

<h1>{{ title }}</h1>
<div class="author">Author: {{ author }}</div>
<div class="content">
{{ content }}
</div>

Now, you are free to replace the template (or collection of templates) with another one without affecting how the site works.