Magento {{depend}} combined with {{config path='some/value/here'}}

Question

we are using the {{depend}} functionality to check for true on a system config variable

But now we are running into the following. Can I combine these special {{}} tags within each other? For example if I want to check config path='some/value/here' to be TRUE, would I do it as follows?

{{depend {{config path='some/value/here'}}}} text here 

Question: How can I use the depend to check a config path value?

And maybe a second question is: does depend check for empty, or does it also understand yes and no's from the config?

Many thanks

Answer 1

You cannot use {{depend}} and {{config}} in that combination for 2 reasons.
The first and most important is that the regex match is screwed up like this. If you have a text like this {{depend name}} some text {{/depend}} the matches array looks like this:

Array
(
    [0] => Array
        (
            [0] => {{depend name}} some text {{/depend}}
            [1] => name
            [2] =>  some text 
        )

)

This means that if the value for the variable name evaluates to something else than null false 0 the value in [0] (the expression) will be replaced with the value from [2] (some text).
If you try it with {{depend {{config path="some/path/here"}}}} some text {{/depend}} the matches look like this:

Array
(
    [0] => Array
        (
            [0] => {{depend {{config path='some/path/here'}}}} some text {{/depend}}
            [1] => {{config path='some/path/here'
            [2] => }} some text 
        )

)

The second reason is that the depend conditions must be a variable passed to the template (element inside the _templateVars member).
The work around for this is to pass the value from the config as a variable to the template and then use that variable in the depend statement.
Let's take for example the new order e-mail sending. In Mage_Sales_Model_Order::sendNewOrderEmail()

$mailer->setTemplateParams(array(
    'order'        => $this,
    'billing'      => $this->getBillingAddress(),
    'payment_html' => $paymentBlockHtml
    )
); 

Turn it into this:

$mailer->setTemplateParams(array(
    'order'        => $this,
    'billing'      => $this->getBillingAddress(),
    'payment_html' => $paymentBlockHtml,
    'my_config_var'=> Mage::getStoreConfig('some/path/here')
    )
);

Now you should be able to use:

{{depend my_custom_var}} some text {{/depend}}