Re: What databases have taught me

From: Robert Martin <unclebob_at_objectmentor.com>
Date: Tue, 4 Jul 2006 18:04:08 -0500
Message-ID: <2006070418040895335-unclebob@objectmentorcom>

On 2006-07-02 19:42:08 -0500, "Marshall" <marshall.spight_at_gmail.com> said:

> Robert Martin wrote:

>> 
>> I think you'd need this code anyway if the above query was issued from
>> more than one place.  I doubt you'd want to duplicate the string.

>
> It depends. If we imagine the same query existing in two places
> in the code, and imagine what could make us want to change it
> in the future, do we imagine that we'd necessarily change *both*
> together or might we just want to change one?
>
> There is also the question of how little code can there be such
> that we still call it a coherent abstraction? My general claim is
> that one line of code is typically *not*a coherent abstraction.
> Because once we abstract it as a method, what do we
> need to do to invoke that method? One line of code.
> So we didn't gain anything. (Of course, not all lines of code
> are of equal complexity, so this is not a precise measure.)

My general rule of thumb is that if two identical lines of code change identically over time, then they should be a single line of code in a function that's called twice.

-- 
Robert C. Martin (Uncle Bob)  | email: unclebob_at_objectmentor.com
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Received on Tue Jul 04 2006 - 18:04:08 CDT