Re: gEDA-user: General Layers questions

[John Doty <jpd@xxxxxxxxx>]

On Feb 15, 2011, at 9:40 AM, Stephan Boettcher wrote:

> DJ Delorie <dj@xxxxxxxxxxx> writes:
> 
>> The two words mean two different things in the English language.
> 
> sorry, I wasn't clear on these distinctions.

DJ has a very narrow and negative viewpoint on factoring.

>  
> 
>> Refactoring means changing nonfunctional attributes of the software
>> (i.e. rearranging code to be more maintainable).

Way, way too narrow. Refactoring can dramatically increase the power at the users' fingertips. Consider a favorite Brian Kernighan example. Take the Multics command:

how_many_users

In Unix, refactor it into:

who | wc -l

Now, you've given the user much more power with fewer commands. For example,

ls | wc -l

counts files, something I recall there was no command for in Multics. 

The large suite of inflexible, specialized commands in Multics collapsed into a much smaller set of commands that were specialized in one sense (what abstraction was served) but generalized in another (what end was served) in Unix. This put a lot more power in users' hands: many things that would have required a page of tricky PL/I code in Multics became simple shell one-liners in Unix. It was much easier to master and remember the smaller, but more powerful, set of Unix commands.

>>  If we're talking
>> about changing functionality (as we were in this case), we need to use
>> a different word.

Functionality emerges naturally from good factoring. Without good factoring, functionality requires a large number of complex "features" that are difficult to remember and often don't play well with each other.

John Doty              Noqsi Aerospace, Ltd.
http://www.noqsi.com/
jpd@xxxxxxxxx




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