Potential Network SIG

Johan Tibell johan.tibell at gmail.com
Tue Aug 25 04:49:43 EDT 2009

On Mon, Aug 24, 2009 at 11:59 PM, Duncan
Coutts<duncan.coutts at worc.ox.ac.uk> wrote:
> On Mon, 2009-08-24 at 09:59 +0200, Johan Tibell wrote:
> Yes, I think this is a trap that we often fall into, that we think we
> make libraries better by providing exactly the one function that people
> need, in some kind of "high level" "all in one" operation.
> As an example, I'm going to pick on Don because I know he can take
> it ;-).

I think I mentioned this to Don months ago when I decided to against
using the library due to all the dependencies. :)

> Let the user / caller do the composition. The API is simpler and easier
> to understand if the user does the composition rather than providing
> every use case. Also the package dependencies are much simpler.
> Sure, point out in the docs that the user could use it that way with
> other libs but don't provide every composition in the name of
> convenience.
> A Microsoft blogger has a nice short (and rather sarky) article on this
> topic:
> "Programming means that sometimes you have to snap two blocks together"
> http://blogs.msdn.com/oldnewthing/archive/2009/08/04/9856634.aspx

Another example: At work we have a File class that has a whopping 20
methods for opening a file. Most methods are combinations of different
ways to do error handling, locking, setting attributes and options.
The whole class has more than 100 methods!

I've seen arguments on the form

    Lots of people write programs that contains the function foo = bar
. baz. Therefor we should put foo in library X.

on the libraries list lately. I think this argument is bogus most of
the time. If you want 'foo', stick it at the top of your module. New
functions should add functionality that is difficult to express using
the current set of functions in the library.

-- Johan

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