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Domain Modeling Made Functional
book

Domain Modeling Made Functional

by Scott Wlaschin
January 2018
Beginner to intermediate
312 pages
7h 22m
English
Pragmatic Bookshelf
Content preview from Domain Modeling Made Functional

Change 2: Adding Support for VIP Customers

Let’s now look at a change that affects the overall input of the workflow. Say that the business wants to support VIP customers—customers who get special treatment, such as free shipping or a free upgrade to overnight delivery.

How should we model this?

One thing we should not do is model the output of a business rule in the domain (such as adding a “free shipping” flag to the order). Instead, we should store the input to a business rule (“the customer is a VIP”) and then let the business rule work on that input. That way, if the business rules change (which they will!), we don’t have to change our domain model.

We’ll assume that somehow the customers’ VIP status is associated with their login on the ...

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Publisher Resources

ISBN: 9781680505481Errata Page