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POPreferring dictionaries over objects in Python
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copied!<p>Are there benefits to using dictionaries instead of objects in Python (or vice versa) when all you're doing is describing something's properties?</p> <p>The project I'm working on currently has a number of places where dictionaries are used where I would have normally created objects. In my mind objects provide more structure and allow for better programmer-error checking by programs such as pylint, but it's difficult to explain <em>why</em> I would use an object rather than a dict.</p> <p>For a mock example, one module creates Widgets and contains a method such as this:</p> <pre><code>def create(self, propertyA, propertyB=55, propertyC="default", propertyD=None, propertyE=None, propertyF=None, propertyG=None, propertyH=None, propertyI=None): </code></pre> <p>That method would be called by creating a dictionary and passing it in much like this:</p> <pre><code>widget_client = WidgetClient() widget = { "propertyA": "my_widget", "propertyB": 10, ... } widget_client.create(**widget) </code></pre> <p>When I see this, I see that every single one of those properties is what describes a 'Widget' and want to do the following:</p> <pre><code>class Widget(object): """Represents a widget.""" def __init__(self, propertyA, **kwargs): """Initialize a Widget. :param propertyA: The name of the widget. :param kwargs: Additional properties may be specified (see below). :returns: None """ self.propertyA = propertyA self.propertyB = kwargs.get("propertyB", 55) self.propertyC = kwargs.get("propertyC", "default") self.propertyD = kwargs.get("propertyD", None) self.propertyE = kwargs.get("propertyE", None) self.propertyF = kwargs.get("propertyF", None) </code></pre> <p>And then update the create() method to look something like this:</p> <pre><code>def create(self, widget): </code></pre> <p>Which ends up being called like this:</p> <pre><code>widget_client = WidgetClient() widget = Widget(propertyA="my_widget") widget.propertyB = 10 ... widget_client.create(widget) </code></pre> <p>In my mind this is clearly better, but I've been wrong in the past and I can't think of how to explain myself. Of course I'm still using **kwargs which could be avoided by breaking the Widget down into smaller component/related parts and creating more objects etc etc, but I feel this is a good "first step". Does this make any sense at all?</p> <p><strong>Dictionary Benefits</strong>:</p> <ol> <li>Faster and/or more memory efficient</li> </ol> <p><strong>Dictionary Drawbacks</strong>:</p> <ol> <li>Inability to catch some errors with static code checkers</li> <li>A full list of all widget properties may never appear or be known</li> </ol> <p><strong>Objects Benefits</strong>:</p> <ol> <li>Knowing exactly what a 'Widget' is comprised of</li> <li>Potentially catch errors with static code checkers (although the use of ** magic prevents some of that)</li> </ol> <p><strong>Object Drawbacks</strong>:</p> <ol> <li>Slower and/or less memory efficient</li> </ol> <p>This seems like a silly question, but why do something with objects that can be done with dictionaries?</p>

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