VAT: The Price Display Handler

Yes, this function would replace uc_currency_format() everywhere. Additional $price must get an object with more informations like $node->nid, $node->price, $qty and sth about "where we are" (if to display some suffix). Example patch for uc_product.module attached.
In general it works great, but e.g. in the cart view (with the block I am fine) I am still running into a wall as there are no detail informations anymore. I must check CA.

If there is no handler installed, you get the output as usual. This is working stable. As the design is now, TR would provide an alternative multi-currency handler for the US mode, I would call sth he provides or what I write. I was not totally sure about your interest in multi-currency. The other thing is that I believe there are just 2 needs for a display modifier: VAT and multi-currency. Everything else are price modifiers.

Does TR already work on a UC2.x version?

The design is now that the user has to decide for one handler which has full responsibility for the output. My suffix stuff has already now various options, will later optional call uc_currency_format() once more, even possibly in a different currency which I would cover without TR's contrib as this is not in his design. (Todays Slovak, later others need).

I thought about a specialized multi-currency hook at the end of uc_currency_format() for TR, modifying the value and changing the currency sign, which would keep things simple. My alternative would be total control what happens here. You are right that this is not finished. Multiple calls of hook_uc_price() sounds great, but might take me some time to get it working.

Do You have some concrete idea who else than VAT and multi-currency would need to modify the display value?

I am all the time convinced that this is the only way to solve VAT clean & other display issues like multi currency support.

A tax is a tax, independent if it is called "sales tax", "VAT", "GST" or whatever.
If to display it everywhere or just at checkout, is a display rule, not a price modifier rule.

However - the energy goes somewhere different, so I try to support what's going on.

For completeness I attached my latest version of this patch.

If the CA condition I heard about last night won't add taxes to the prices (also line-items) in the order, then this patch will be somewhere between postponed and obsolete. Multi currency support we can achieve also differently ;)