Sometimes you need to evaluate the whole quote and then pass that result to the line items.
Some of the use cases:
- You need to evaluate the "type" of the quote – if the products are from the same category or from mixed categories. Depending on that you will make different calculations for the line items.
- You want to evaluate the mix of the line items and in certain cases add a new line (via the header logic) to the list of products on the quote. But you want to avoid the situation that this addition will happen again the next time you press "Calculate Quote". So you need to set some "flag" on the line item which causes the new line being added.
In both these examples we need to pass some information from the header logic to the line item.