Julio Biason
3 years ago
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title = "The Types of OOP" |
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date = 2022-05-31 |
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draft = true |
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[taxonomies] |
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tags = ["programming", "oo"] |
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+++ |
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I'm seeing that a large group of newcomers don't get the idea behind object |
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oriented programming. And I think this misunderstanding is basically the way |
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this is explained. |
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If we take a page from the classical "first look" at OOP, we would see something |
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like |
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```python |
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class Animal: |
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def say(self): |
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print("Don't know what to say") |
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class Dog(Animal): |
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def say(self): |
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print("Woof!") |
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``` |
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The example usually creates a base class, with a method (function), extends the |
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base class in a child class and overrides the method. And that's basically it. |
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But, in real life, things are not quite like that. |
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Ok ok, there are examples in real life that are basically that, but I don't |
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think we *start* with that, we *use* that. |
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So, what do I mean by "Types of OOP"? |
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## The Grouping |
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One of the types of OOP we usually do is "grouping". What do I mean by that is |
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that we usually have a group of values that are related and should be worked |
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together. |
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For example, in stock markets, we have the concept of a "candle": The candle |
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summazes what happened in a period of time -- be it one day, one hour, one |
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minute of 10 milliseconds. In that space of time, we capture the first value |
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seen, the last value, the highest value and the lowest value. We could, for |
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example, use a series of arrays for that, like |
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```python |
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first_values = [10, 20, 14, 21, 17] |
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last_values = [20, 14, 21, 17, 12] |
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high_values = [30, 20, 21, 21, 18] |
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low_values = [9 , 14, 13, 17, 12] |
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``` |
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Here, each "column" represents one entry in the period time; if we are doing it |
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per hour, that means in the first collected hour we have the values in the first |
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column, one hour later we have the values in the second column and so on. Thing |
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is, those values are related, and we could basically group them together. |
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```python |
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class Candle: |
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def __init__(self, first, last, high, low): |
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self.first = first |
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self.last = last |
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self.high = high |
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self.low = low |
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entries = [ |
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Candle(10, 20, 30, 9), |
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Candle(20, 14, 20, 14), |
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Candle(14, 21, 21, 13), |
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Candle(21, 17, 21, 17), |
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Candle(17, 12, 18, 21), |
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] |
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``` |
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This is basically the same thing, but now instead of having multiple arrays, we |
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have just one that keeps all related information together. The concept of |
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grouping information like that is not something new and even C had a `struct` to |
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keep related values together. But when we use objects, we can also add |
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"behaviours" to our data, and we could ask if the candle is going up or down, if |
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that would help us in our requirements. |
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A simple example could be the name of a person |
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``` |
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class Name: |
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def __init__(self, first_name, last_name): |
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self.first_name = first_name |
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self.last_name = last_name |
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def full_name(self): |
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return "{} {}".format(self.first_name, self.last_name) |
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``` |
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For a person, we have related information like the first name and last name. But |
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if we want to put their names in an envelope, we need to print both names |
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together, so we added a "behaviour" (method) to produce that for us. |
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Quite simple. |
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## The Façade |
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