Add dataclass tutorial

Python/035_dataclass.py

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+# Intro to Python Dataclasses
+
+from dataclasses import dataclass
+
+# Here is a fantastic in-depth guide for Data Classes
+# https://www.dataquest.io/blog/how-to-use-python-data-classes/
+
+# In Python, a data class is a class that is designed to only hold data values.
+# They aren't different from regular classes, but they usually don't have any
+# other methods. They are typically used to store information that will be
+# passed between different parts of a program or a system.
+
+# Data classes automatically create the __init__ method (which is called
+# a "constructor" and will be discussed in a subsequent totorial).
+# This saves a fair bit of coding when a class is designed to just contain
+# attributes/variables, and reduces the liklihood of errors.
+
+# A dataclass is created by putting "@dataclass" by itself on the line
+# before the class definition statement
+@dataclass
+class Shape():
+    label: str=""
+    fill: bool = True
+
+# Dataclasses can inherit from parent classes just like traditional classes.
+# Class inheritance and other class details such as methods will be discussed
+# in more detail in a subsequent tutorial.
+@dataclass
+class Circle(Shape):
+    center_x: int = 0
+    center_y: int = 0
+    radius: int = 0
+
+# In the above class definition, all attributes have default values.
+# This means that a new object can be instantiated without passing
+# any parameters to the class. i.e. my_circle = Circle()
+#
+# Attributes do not have to have default values provided.
+# However, there are two requirements if they do not.
+#    1) All parameters without default values must have values
+#       provided when instantiating an object.
+#       Such as: my_circle = Circle("Tiny")
+#    2) Attributes without default values MUST be declared in the
+#       class definition BEFORE any parameters with default values.
+#       They cannot come after.
+
+# Instantiate a Circle() object with default values
+my_circle = Circle()
+# Change one of the class variables/attributes
+my_circle.label = "Boss"
+print(my_circle)
+# If values for attributes are passed to the class they must be in the
+# same order as the attributes listed in the class definition.
+# If instantiating a child class then all parent parameters must be
+# specified before those in the child.
+my_circle = Circle("B1", True, 40, 100, 40)
+print(my_circle)
+# Named Parameters: Parameters passed to the class can be named. This
+# serves two purposes. The first is that it makes the instantiation
+# unambiguous which can be helpful if the class has many attributes.
+# The second is that it allows a specific parameter to be assinged
+# a value without specifying all of the intervening parameters.
+my_circle = Circle("But1", radius=40)
+print(my_circle)