[Chicago] Factoring fun with functions in Python

Martin Maney maney at two14.net
Thu Nov 15 14:15:01 CET 2012

On Tue, Nov 13, 2012 at 08:35:17PM -0800, Dan Krol wrote:
> One thing I struggle with on this count is that spitting it up to this
> degree makes it confusing all over again, because there's so many
> functions, so many lines of logic to follow. There's no indicating what the
> "main idea" is, you just have to read it all to find out what isn't being
> called by everything else.

The intention may have been to suggest a good design approach, but if
so it's a really poor example.  I've been struggling with finsing a way
to talk about the problems, and I think Google has finally found me a
simple way to approach it.  Read this:


The whole issue of module size is, at best, an approximation to the
real issues of cohesion and coupling.  And, yeah, none of this has
changed all that much since the seventies.  At the most, OOP and FP and
fad-of-the-month-Programming have all been, at bottom, attempts to make
good cohesion and low coupling "just happen".

Have you ever considered that an object is a bunch of related functions
with a bunch of locally-global variables?  Not, perhaps, the best OOP,
but c'mon, I'm sure you've seen this if not written it yourself. 
Nested functions, likewise, have value, but often suffer from the
"simplification" of implicitly sharing the enclosing-and-calling
scope's locals as the nested function's globals.  Back int he day
FORTRAN had this named COMMON thing to support the same concept.

> Any ideas on that front? Isn't there such a thing as splitting functions up
> *too* much?

>From Ch07:

  If a software organization insists that modules must be neither too
  big nor too small, then two undesirable things happen.  First, two or
  more otherwise ideal smaller modules are lumped together to create a
  larger module with coincidental cohesion.  Second, pieces hacked from
  well-designed modules that management considers too large are
  combined, again resulting in modules with coincidental cohesion.

If nature has made any one thing less susceptible than all others of
exclusive property, it is the action of the thinking power called an
idea, which an individual may exclusively possess as long as he keeps
it to himself; but the moment it is divulged, it forces itself into
the possession of every one, and the receiver cannot dispossess
himself of it.  -- Thomas Jefferson

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