Why wouldn't these theme functions work with Drupal D6? - drupal

Question

I'm at my wits end with Drupal 6 right now, and I'm hoping a second pair of eyes might be able to point out some syntax sublety I was missing earlier this morning.
Lets say I have a theme called my_theme.
This is a theme that subthemes from Ginkgo, a theme which which in turn subthemes from
Rubik, whith in tun subthemes from Tao, a fairly common CSS reset theme.
I'm trying to understand how to declare my own theme functions, so I can
clean up the mark up on a fee page I'm workign on for site.
Now my understanding of theming is along the lines of ' if register a
theming function with hook_theme, passing it into an array, with the
function's name, you'be able to call it in future with
theme_function_name from within your theme.
For example, if have a module called my, I'd immplent the hook_theme
like below, defining the name of the function, and defining which
argument should be passed into it:
<?php
function my_theme() {
$items = array();
$items['randomtext'] = array('arguments' => array('element' => NULL));
$items['button_links'] = array('arguments' => array( '$links' => NULL, '$attributes' => NULL));
return $items;
};
Now I have the functions registered, I just need to implement them like
this somewhat contrived example:
function theme_randomtext($element) {
$output = ' <h1>This is some very random text with' . ' this text concatenated: ' . $element . '</h1>';
return $output;
}
I can now use this new function by calling
<php
print theme('randomtext', 'some arbitrary words')
?>
And expect the following content to be returned:
<h1>This is some very random text with this text concatenated: some arbitrary words</h1>
I'm getting nada.
And I don't know why. When I look at the theme registry, I see my
function listed as my_randomtext - I've tried calling both of these
options, in case I should have been adding the theme prefix:
theme('my_randomtext', 'getting desparate');
theme('randomtext', 'really losing my rag now');
Still no luck.
Why might these theme functions not be working? And what advantage does
this give you over simply declaring a function like so in a theme?
function manual_random_text($element) {
$output = ' <h1>This is gives me everything I aleady need,
'without relying on the weird themeing sytem. It's perfect for' . $element . '</h1>';
return $output;
}

Answer 1

Ah, after a bit of distance from the problem, I see the issue.
For this to work, I need to add the prefix of the theme I declare the function in, to make it available to me for use.
So if my module name was my, the desired theme function name would be:
function my_random_text($element) {
$output = ' <h1>,
'This is finally outputting content. Now I can: ' . $element . '</h1>';
return $output;
}
The thing is, if I'm creating an override to a theme function that doesn't already exist, like random_text, there are no functions for it to override anyway.
The term theme override suggests there being a default theming function to override - in many themes, we're not making explicit overrides of functions, but creating alternatives to use in specific cases.
I'm now assuming that I'd need to define this in a module if I wanted to define a function as theme_function_name rather than themename_theme_function_name.
This page here about theming on Drupal.org was a useful quide in finding out some of this info.