Re: Critique of Robert C. Martin's "Agile Principles, Patterns, and Practices"

On 2007-01-21 13:59:25 -0600, "topmind" <topmind@xxxxxxxxxxxxxxxx> said:

Isolation creates duplication of concepts and can make it more
difficult to use the existing power and abilities of RDBMS. Most of the
code in your book is WASTED on translating back and forth between two
medium-to-high-level concepts: OO and relational. It is like spending
effort translating between Japanese and Spanish and back rather than
get anything real done.

The payroll system in the book is partitioned into code that knows about the DB schema, and code that does not. The dividing line is a set of interfaces that translate high level concepts like "GetEmployee" into appropriate SQL. To the left of the interfaces the code deals with Employees. To the right the code deals with SQL, tables, rows, and columns.

In any application, OO or not, this translation must take place. All we have done with the code in the book is to assign a place for that translation.

There is no duplication. There is no waste. There is simply a separation of concerns. Those concerns would exist regardless of whether they were separated or not.

--
Robert C. Martin (Uncle Bob)  | email: unclebob@xxxxxxxxxxxxxxxx
Object Mentor Inc.            | blog:  www.butunclebob.com
The Agile Transition Experts  | web:   www.objectmentor.com
800-338-6716                  |



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