To retrieve a document using Cushion:

To create a document with a document id using Cushion:

To install Cushion: easy_install cushion. If you’re interested, the source code and more documentation is available on GitHub: git://github.com/sheysrebellion/cushion.git

Relax, enjoy.

We rely on polymorphism and design patterns to help reduce complexity; often those solutions are well suited for static programming languages like Java, but feel ceremonious in languages like Python and Javascript. If you’re programming in a dynamic programming language that supports dictionaries out of the box, then you may find the Dispatch Table “pattern” a useful way to simply your code.

The pattern uses a dictionary where the keys represent possible actions, and the value of each key contains a callable that does the actual work. Compared to if-else statements, dispatch tables require fewer lines of code, and we know fewer lines of code equals fewer bugs.

Here’s a mostly real world example that creates handlers for webhooks. You can imagine how long the if-else statement, that is used to decide which handler to instantiate, can become, especially when the consuming code has to respond to multiple keys.

Neat.

Instead of defining a factory class and a creation method on that class, I define creation function which accepts the dependencies as parameters, partially apply them and use the new function as my “creation function.” I prefer the second example, I enjoyed writing it, but both examples perform the same function with essentially the same number of lines and ultimately my preference is as basic as preferring a functional style of programming over object oriented.

So I’m wondering, how do other developers use currying or partial application in their projects?

With Sparkplug, you create a configuration file, then define Consumer class to handle each message. As messages are pushed into the queue, Sparkplug will call your class and you decide how you want handle the message in the __call__ method. The great thing about this is that all the connection logic is removed from your code letting you concentrate on how you want to handle each message.

Now you can run your app using sparkplug --daemon consumer.ini. Configuration is boring, so I’ve left the consumer.ini out of the blog post and put it up on github instead.

To balance expressive with conciseness, I’ve refactored the builder to use Python dictionaries

I find this code to be just as expressive, easier to use and most importantly not repetitive.

The few discussions I read online implied that Python doesn’t need an IoC framework because it is a dynamically typed language.  Dynamically typed languages eliminate the need to use interfaces, they do not do away with the need for inversion of control.

IoC is used to decouple components of an application, remove direct dependencies so that replacing a component will not have a side effects on the rest of the system.  As Dave Thomas explains

a DI application is written as a set of loosely coupled components. These components contain no knitting code: nothing in the application code itself is responsible, for example, for making sure that the necessary objects somehow get an instance of the database connection. Instead, the components all run in a container. This container is given a description of the knitting to be done (typically using an XML file). The container then instantiates objects and sets them into components that need them

I’m new to the language and there maybe a more “pythonic” way to handle inversion of control than using a container. Here is small and contrived example of inversion of control using Pinsor, a IoC container in Python. Those coming from a .NET or Java background will find Pinsor easy to use, but slightly lacking in features.