Composition over inheritance in object-oriented programming is a technique by which classes may achieve polymorphic behavior and code reuse by containing other classes which implement the desired functionality instead of through inheritance.^[1]

The Strategy Design Pattern is idea is to decouple as much as possible to maximize code use. It looks kinda like this code from S-Lott on  Stack Overflow on Strategy:

class AUsefulThing( object ):
    def __init__( self, aStrategicAlternative ):
        self.howToDoX = aStrategicAlternative
    def doX( self, someArg ):
        self. howToDoX.theAPImethod( someArg, self )

class StrategicAlternative( object ):
    pass

class AlternativeOne( StrategicAlternative ):
    def theAPIMethod( self, someArg, theUsefulThing ):
        pass # an implementation

class AlternativeTwo( StrategicAlternative ):
    def theAPImethod( self, someArg, theUsefulThing ):
        pass # another implementation

Now you can do things like this.

t = AUsefulThing( AlternativeOne() )
t.doX( arg )

S-Lott then provides another Python example pattern that replicates the above with a bit less code.

This had me scratching my head. Not at the example and the helpful response, but at the question itself. Why are we creating functions, then assigning a variable to a class and passing the function in as a parameter? Barooo?

Then on the same stack overflow post there was a follow up response from Christian Groleau as follows:

This pattern is practically non-existent in languages that support first class functions. You may want to consider taking advantage of this feature in Python:

def strategy_add(a, b):
    return a + b

def strategy_minus(a, b):
    return a - b

solver = strategy_add
print solver(1, 2)
solver = strategy_minus
print solver(2, 1)

“This approach is very clean and simple.”

I agree with him. I have made the mistake, granted it was out of desperation, of putting a literal in a public property in a class called “objecttype”. This let me pass the object to a function and make decisions on what to do next. Pseudo vbscript-ish code example:

function generate_invoice(object, d)
    select case(object.objecttype)
        case "jobs"
        #do job invoice stuff
    case "resumes"
        #do resume stuff here
    case else

Ok, so it’s not quite as bad as concatenating a string of vbscript and calling the exec(str) method. But it ain’t pretty either. But both got the job done. And in the case of my fake function above, that sure looks like the composition pattern to me. Maybe not exactly, but it’s close. Functions taking classes as parameters and then calling methods within the class in the name of portability. And to reduce code in the classes themselves of course.

I like Christian’s example above a LOT better. Which makes sense because Python has, as noted by bitwise, both First Class Functions and allows for Meta-programming. “Python is not java without the compile” indeed. First Class Functions and Meta Programming used in combination obviate the need for the Strategy design pattern in Python IMHO (see caveats below). And for further support I found this:

From pycon 2009 – Joe Gregorio – The (lack of) design patterns in Python

“Yes, design patterns are good, but they’re also a sign of weakness in a language.”

The patterns are built in [to Python]. “No one talks about the ‘structured programming’ pattern, or the ‘object-oriented’ pattern, or the ‘function’ pattern anymore.”

………

Conclusions:

1. look to features before patterns
2. reduce patterns -> shorter code
3. needed patterns -> language feature

I’m still a Python newb, but definitely not a programming newb. And So far it looks like you can inherit meta classes with properties to your hearts content to DRY. Yet still, make a thoughtful decision when it comes to how you should implement methods/functions in base classes. Sometimes perhaps a function is better than inheriting a method. Just stop and think. Odds are our fear of inheritance is a learned behavior from being burned by java or another similar lower-level language. I think I need to get over that.

And be thankful that most design patterns are already built into Python. Less code is better.

In closing, and I forget the post I read it on, but just because programming can do ORM (object relational mapping) does NOT mean that a database can. In fact it can’t. And a database deals with the multi-stand-alone class issue by creating a bunch of tables in Django. And one programming matra that I am 100% sure is true is “JOINS are EXPENSIVE.”

Django responds to inherited meta classes by keeping all of the fields in one table, not 20. And perhaps this is me just trying to get over my fear of multi-inheritance and break years of practice. To take advantage of Python being “First Class Everything”. To write code that is  Better, faster, stronger than before.

“I respect the beliefs of others, and the right of religious institutions to act in accordance with their own doctrines. But I believe that in the eyes of the law, all Americans should be treated equally. And where states enact same-sex marriage, no federal act should invalidate them.”

- POTUS, 2012

Commentary: Yes I realize my job is a “role”, that of CEO. Yet sometimes I reserve the right to point out what I believe to be obvious. Sometimes that obviousness is bigotry in the form of discrimination against people for the way they were born, created, by God.

Example:

In 1981 when I met a good friend it was clear to me he was “born that way”. The first week of high-school we all didn’t know how to react to him. What was his deal? Huh? Turns out he is a great man. Different from many of us. Being born gay, something we all knew but he didn’t confirm until many years later. If asked he denied it. We didn’t care because he was a good friend and a good man. Period. He was part of our tribe and good heavens we all had our own weirdness.

Years later I remember the call when I was in college when he said “I have something to say” and I said “we know, we knew in high school, and it doesn’t change a bloody thing. We love you as you are dude.” His response was “you knew?” and, for lack of a more refined response I said something like “we all knew, we didn’t care, and I’m pretty sure you knew even back then but that doesn’t matter. You rock and it’s so great to hear from you.”

I’d have my PR team refine my response now. But it wouldn’t change the message.

I stand by my statements. I’d do the exact same thing today. I do. Accept.

Different? Yes, a minority. But God’s creation. This wasn’t some “choice.” This was simply who the man was. He was born that way. And who am I to judge how God creates us? Do I really understand it? No. Do I understand at a logical level why I find women attractive? No. We are truly just “born that/this/the-other way.”

So regardless of your politics, I love hearing the President of the United States state clearly his support of gay rights. States rights first, yes, but given a states’ choice the Federal Government should stay out of it. And I rarely agree with politicians, but in this case, I  agree. Tip of the hat to your courage POTUS. Keep on keepin on.

And a panorama from shots from the video:

Scores of readers, often students, wrote to Wilder over the years seeking his position on the questions posed in The Bridge. In this excerpt from a letter written march 6, 1928, four months after the appearance of the novel, Wilder responds to a query from John Townley, one of his former pupils at Lawrenceville.

The first:

Thornton Wilder
Davis House
Lawrenceville, New Jersey

Dear John:

The book is not supposed to solve. A vague comfort is supposed to hover above the unanswered questions, but it is not a theorem with its Q.E.D. The book is supposed to be as puzzling and distressing as the news that five of your friends died in an automobile accident. I dare not claim that all sudden deaths are, in the last counting, triumphant. As you say, a little over half the situations seem to prove something and the rest escape, or even contradict.

Chekhov said: “The business of literature is not to answer questions, but to state them fairly.”

I claim that human affection contains a strange unanalyzable consolation and that is all. People who are full of faith claim that the book is a vindication of this optimism; disillusioned people claim that it is a barely concealed “anatomy of despair. I am nearer the second group than the first; though some days I discover myself shouting confidentially in the first group.

Where will i be thirty years from now? – with Hardy or Cardinal Newman?

- Thornton Wilder

Afterward, The Bridge of San Louis Rey

Services for Kenan are this Saturday, the 28th of April, 2012.

A message that was sent out to the Houston Netsquared Meetup Group tonight in memory of our  friend and colleague Kenan Doyle Branam. He was a debater, optimist, producer, geek, well read, researched, and all around renaissance man. We will miss you Kenan. Even if you challenged us constantly with debates and thoughts Kenan, I wouldn’t have wanted it any other way. A tip of the hat to you. You will be missed.

April 26, 2012

All,

Sad news….

If you have attended Net2Houston over the last six years, then you know Kenan. His meetup profile says Kenan attended 28 meetings with us, although I think it may have been even morehttp://www.meetup.com/houston-netsquared/members/3125708/

Kenan Doyle Branam was a Netsquared regular who always asked challenging questions from the heart. An optimist, he always found the positive, which was impressive given his posts frequently talked about his growth from being a skeptic to an optimist over time. What a beautiful transition.

I’m sad to say that Kenan passed away unexpectedly last week and his services are this weekend. The official notice is below. If you can attend i know Kenan would be honored as would his family. The official version follows. And I know the family would appreciate help with the costs of the funeral. Please consider the part at the bottom about the fund at Amegy in lieu of flowers, but your presence on Saturday would be a huge tribute as well.

Thanks,

Ed

—————

The Houston Advertising, Media and Production Community lost one of its own in the sudden passing of Kenan Doyle Branam on Saturday April 14, 2012.  Services will be this Saturday April 28th 2012 here in Houston.

Beginning his long career in media, Kenan worked as a cameraman in the local broadcast television station in Tyler. In addition to this his media experiences later included advertising agency client service, corporate communications, point of sale training, and even documentary and music video work. 

Kenan was President of Paradigm Communications, Inc. for 25 years, and most recently worked as a Media Consultant supporting people to show up, be heard, look and feel good about their web presence.  Throughout his long career he was a careful watcher and analyzer of media. He was, in his own words “a philosopher, then an artist, then a media evangelist”

A great number of local organizations were fortunate to have Kenan initiate lively and thought provoking conversations while bringing his gifts of philosophy, kindness, laughter and an artistic sensibility to their gatherings.

A Life Celebration for Kenan will be held

Saturday, April 28, 2012 at 3:00 PMTotal Video at Houston Studios
707 Walnut, Houston TX 77002.

In lieu of flowers, donations in Kenan’s memory can be made (and would really help his family at this time) at any

Amegy Bank for the Memorial Fund for Kenan Doyle Branam.

I always say I work only with people I love and I can make only things I love.

- Alber Albaz