CodeSOD: Dictionary Definition

Guy's eight-person team does a bunch of computer vision (CV) stuff. Guy is the "framework Guy": he doesn't handle the CV stuff so much as provide an application framework to make the CV folks lives easy. It's a solid division of labor, with one notable exception: Richard.

Richard is a Computer Vision Researcher, head of the CV team. Guy is a mere "code monkey", in Richard's terms. Thus, everything Richard does is correct, and everything Guy does is "cute" and "a nice attempt". That's why, for example, Richard needed to take a method called readFile() and turn it into readFileHandle(), "for clarity".

The code is a mix of C++ and Python, and much of the Python was written before Guy's time. While the style in use doesn't fit PEP-8 standards (the official Python style), Guy has opted to follow the in use standards, for consistency. This means some odd things, like putting a space before the colons:

 def readFile() : # do stuff

Which Richard felt the need to comment on in his code:

 def readFileHandle() : # I like the spaced out :'s, these are cute =]

There's no "tone of voice" in code, but the use of "=]" instead of a more conventional smile emoticon is a clear sign that Richard is truly a monster. The other key sign is that Richard has taken an" unusual approach to object-oriented programming. When tasked with writing up an object, he takes this approach:

class WidgetSource: """ Enumeration of various sources available for getting the data needed to construct a Widget object. """ LOCAL_CACHE = 0 DB = 1 REMOTE_STORAGE = 2 #PROCESSED_DATA = 3 NUM_OF_SOURCES = 3 @staticmethod def toString(widget_source): try: return { WidgetSource.LOCAL_CACHE: "LOCAL_CACHE", WidgetSource.DB: "DB", #WidgetSource.PROCESSED_DATA: "PROCESSED_DATA", # @DEPRECATED - Currently not to be used WidgetSource.REMOTE_STORAGE: "REMOTE_STORAGE" }[widget_source] except KeyError: return "UNKNOWN_SOURCE"def deserialize_widget(id, curr_src) : # SNIP widget = { WidgetSource.LOCAL_CACHE: _deserialize_from_cache, WidgetSource.DB: _deserialize_from_db, WidgetSource.REMOTE_STORAGE: _deserialize_from_remote #WidgetSource.PROCESSED_DATA: widgetFactory.fromProcessedData, }[curr_src](id)

For those not up on Python, there are a few notable elements here. First, by convention, anything in ALL_CAPS is a constant. A dictionary/map literal takes the form {aKey: aValue, anotherKey: anotherValue}.

So, the first thing to note is that both the deserialize_widget and toString methods create a dictionary. The keys are drawn from constants" which have the values 0, 1, 2, and 3. So" it's an array, represented as a map, but without the ability to iterate across it in order.

But the dictionary isn't what gets returned. It's being used as a lookup table. This is actually quite common, as Python doesn't have a switch construct, but it does leave one scratching one's head wondering why.

The real thing that makes one wonder "why" is this, though: Why is newly written code already marked as @DEPRECATED? This code was not yet released, and nothing outside of Richard's newly written feature depended on it. I suspect Richard recently learned what deprecated means, and just wanted to use it in a sentence.

It's okay, though. I like the @deprecated, those are cute =]

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