Epiphany.

In Python, with iterators, the Visitor design pattern is useless. And a strongly-ingrained habit. Which I'm trying to break.

Here's a common Visitor approach:

class Visitor:
    def __init__( self ): ...
    def visit( self, some_target_thing ): ...
    def all_done( self ): ...

v = Visitor()
for thing in some_iterator():
    v.visit(thing)
v.all_done()

If we …

Check out this month's Hacker Monthly. One of my Stackoverflow answers was reswizzled into a short article on class design. That was gratifying.

Tweet:

People criticize for making tons of small classes instead of fewer larger classes.How is well-organized code more difficult to understand?

—jim christopher (@beefarino) May 31, 2013

This isn't really a question. Writing a few "large" omnibus classes is simply bad design.

There are several variations on the theme …

Some folks love the twin ideas that (1) "someone" might break the API rules and (2) they must write lots of bonus code to "prevent" problems.

Sigh.

There are three distinct things here.

• API definition - something we do all the time.
• "Defensive Programming" - something that may or may not actually …

Emphasis on the "More On" as in "Moron". This is a standard design error story. The issue is that inheritance happens along an "axis" or "dimension" where the subclasses are at different points along that axis. Multi-dimensional inheritance is an EPIC FAIL.

Objects are everywhere.

Weirdly, some people can't see them. I guess they live in a rarified, HP Lovecraftian world of pure action inhabited by amorphous things that can't be properly called "beings" but rather "doings" because they're pure activity with no existence.

Read "Hypnos". "They were sensations, yet within them …

After reverse engineering procedural code in C, VB or even Python, I'm finding that procedural programming inevitably leads to bad, bad code-rot.

Consider some of the common design patterns.

Strategy. Confronted with alternative strategy choices, a purely procedural code solution is either

• If-statements everywhere the strategy is involved.
• Block comments …

Read this first: "There is something I find interesting about online discussions around performance issues..." It's about Stack Overflow, specifically. Apparently, someone didn't get their question answered and decided it was better to gripe than to rewrite the question.

Let's look at their response in pieces.

"people try to gang …

I love hypothetical questions. Got a bunch recently. I guess it's the season for hypotheticals.

These all seem to come from the "Averted Glance" school of management. The best part about the "I don't want to know the details" management is that we need to substitute metrics for understanding. One …

Recently, I had two very weird "meta" questions on the subject of OO design.

They bother me because they imply that some Brother or Sister Architect has let slip the presence of the Secret Technologies that we Architects are hiding from the Hoi Polloi developers.

These are the real questions …