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        <title>Intro to Python ~ Girl Develop It</title>

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            <!-- Any section element inside of this container is displayed as a slide -->
            <div class="slides">
              <!-- Opening slide -->
                <section>
                    <img src = "images/gdi_logo_badge.png">
                    <h3>Intro to Python</h3>
                    <h4>Class 4</h4>
                </section>

                <section>
                    <h3>Review</h3>
                    <ul>
                        <li>Method calls</li>
                        <li>Combining lists and dictionaries</li>
                        <li>Builtins for collections</li>
                    </ul>
                </section>

                <!-- Block 1  - Intro to Classes and OOP - 20 minutes -->
                <section>
                    <h3>Functions on Dictionaries</h3>
                    <p></p>
                    <pre><code contenteditable class="fragment python">
character = {
    'x': 10,
    'y': 20,
    'health': 100,
}

def injure(character, damage):
    character['health'] = character['health'] - damage
    if character['health'] < 0:
        character['health'] = 0

def heal(character, amount):
    character['health'] = character['health'] + amount
    if character['health'] > 100:
        character['health'] = 100
                    </code></pre>
                </section>

                <section>
                    <h3>Classes</h3>
                    <p>A <strong>class</strong> creates a new type of object.</p>
                    <p class="fragment">A class defines the attributes and methods of objects of that type</p>
                    <p class="fragment">Classes are used to create new objects of that type</p>
                    <pre><code contenteditable class="fragment python">
class Character():

    def __init__(self, x, y, health):
        self.x = x
        self.y = y
        self.health = health

character = Character(10, 20, 100)
                    </code></pre>
                </section>

                <section>
                    <h3>A Sense of Self</h3>
                    <p>The first argument to every method is <strong>self</strong>.</p>
                    <p class="fragment">self contains the attributes and methods for the current object</p>
                    <pre><code contenteditable class="fragment python">
class Character():

    def __init__(self, x, y, health):
        self.x = x
        self.y = y
        self.health = health

character = Character(10, 20, 100)
                    </code></pre>
                </section>

                <section>
                    <h3>The __init__ Method</h3>
                    <p>This method defines what the class should do when creating a new object.</p>
                    <pre><code contenteditable class="fragment python">
class Character():

    def __init__(self, x, y, health):
        self.x = x
        self.y = y
        self.health = health

character_a = Character(10, 20, 100)
character_b = Character(10, 20, 100)
                    </code></pre>
                <p class="fragment">To create a new Character, the syntax looks like a function call. These arguments are passed to the __init__ method</p>
                </section>

                <section>
                    <h3>Class Methods</h3>
                    <p>A class also defines <strong>methods</strong>, which are functions that operate on objects of that type</p>
                    <p class="fragment">Assigning values to an attribute on self is how we <strong>mutate</strong> the object's state.</p>
                    <pre><code contenteditable class="fragment python">
# inside the character class

    def heal(self, amount):
        self.health = self.health + amount
        if self.health > 100:
            self.health = 100

    def injure(self, amount):
        self.health = self.health - amount
        if self.health < 0:
           self.health = 0

character = Character(10, 20, 100)
character.injure(10)
                    </code></pre>
                </section>

                <!-- Let's develop it: 10 minutes -->
                <section>
                    <h3>Let's Develop It</h3>
                    <ul>
                        <li>In your text editor, create your own class with an __init__ method, and at least one other method.</li>
                        <li>Open a Python shell and import the class. Create one or more objects from the class</li>
                        <li>If time allows, create a function that creates objects from your class, calls a method, and prints one of its attributes</li>
                        <li>Use the next slide as an example</li>
                    </ul>
                </section>

                <section>
                    <pre><code contenteditable class="python">
# in character.py
class Character():

    def __init__(self, x, y, health):
        self.x = x
        self.y = y
        self.health = health

    def heal(self, amount):
        self.health = self.health + amount
        if self.health > 100:
            self.health = 100
                    </code></pre>
                    <pre><code contenteditable class="python">
# in Python shell
from character import Character
character_a = Character(10, 20, 100)
character_a.injure(10)
print("character health is: " + character_a.health)
                    </code></pre>
                </section>

                <!-- Block 2 - Inheritance and Composition 20 Minutes -->

                <section>
                    <h3>Inheritance</h3>
                    <p>A class can <strong>inherit</strong> from another class.</p>
                    <p class="fragment">A class that inherits from another is called the "child class" and obtains the methods and attributes of its "parent"</p>
                    <pre><code contenteditable class="fragment python">
class Mobile(object):
    """
    An object with an x, y position, and methods for moving
    """

    def __init__(self, x, y):
        self.x = x
        self.y = y

    def move_up():
        self.y = self.y - 1

    # ... methods for move_down, move_left, and move_right
                    </code></pre>
                </section>

                <section>
                    <h3>Inheritance Continued</h3>
                    <p>The move_up method is <strong>overridden</strong> in the child class below:</p>
                    <pre><code contenteditable class="fragment python">
class BoundedMobile(Mobile):
    """
    An object with an x, y position, and methods for moving
    The x, y position must be within bounds
    """

    def move_up():
        self.y = self.y - 1
        if self.y < 0:
            self.y = 0
                    </code></pre>
                    <p class="fragment">See <a href="http://nicklang.com/gdi-intro-python/examples/mobile.py">mobile.py</a> for a more complete example.</p>
                </section>

                <section>
                    <h3>What's Super about Super</h3>
                    <p><strong>super</strong> is often helpful when writing methods that override the method of the parent class</p>
                    <pre><code contenteditable class="fragment python">
class BoundedMobile(Mobile):
    """
    An object with an x, y position, and methods for moving
    The x, y position must be within bounds
    """

    def move_up():
        super(BoundedMobile, self).move_up()
        if self.y < 0:
            self.y = 0
                    </code></pre>
                    <p class="fragment">The call to super() takes the name of the child class, followed by self. This is followed by the method call and any arguments to pass to it</p>
                </section>

                <section>
                    <h3>Composition</h3>
                    <p>Classes can also use the technique of <strong>composition</strong></p>
                    <p class="fragment">This simply means that a given object contains other objects within it.</p>
                    <p class="fragment">This often leads to a clearer and simpler design</p>
                    <pre><code contenteditable class="fragment python">
class Grid(object):

    def __init__(self, x_limit, y_limit):
        self.x_limit = x_limit
        self.y_limit = y_limit
        self.mobiles = []

    def add_mobile(self, x, y):
        mob = BoundedMobile(x, y, self.x_limit, self.y_limit)
        mobs = self.mobiles.get((x, y), [])
        mobs.append(mob)
        self.mobiles[(x, y)] = mobs
                    </code></pre>
                </section>

                <section>
                    <h3>Composition Continued</h3>
                    <p>Given the class on the previous slide, the following code creates mobiles within the grid object. (Complete code is available in the aforementioned <a href="http://nicklang.com/gdi-intro-python/examples/mobile.py">mobile.py</a> file.)</p>
                    <pre><code contenteditable class="fragment python">
from mobile import Grid

grid = Grid(7, 7)
grid.add_mobile(1, 2)
grid.add_mobile(0, 1)
grid.add_mobile(0, 1)

grid.display_grid()
                    </code></pre>
                </section>

                <!-- Let's develop it: 10 minutes -->
                <section>
                    <h3>Let's Develop It</h3>
                    <p>Create a class that uses inheritance, composition, or both.</p>
                    <p>To help you, use your work from the last exercise or the classes from <a href="http://nicklang.com/gdi-intro-python/examples/mobile.py">mobile.py</a></p>
                </section>

                <section>
                    <h3>Higher order functions</h3>
                    <p>A <strong>higher order function</strong> is a function that returns a function, takes a function as an argument, or both</p>
                    <p class="fragment">One commonly used higher order function that is a Python builtin is called <strong>map</strong></p>
                    <pre><code contenteditable class="fragment python">
# Define any function
def sqaure(number):
    return number ** 2

# Pass the function to map along with an iterable
squares = map(square, range(10))
                    </code></pre>
                    <p class="fragment">N.B. - map has performance problems for large data sets and should only be used when the data set is well defined and somewhat small.</section>
                </section>

                <section>
                    <h3>Let's Develop It</h3>
                    <p>Choose among any of these projects (Resources available on the next page):</p>
                    <ul>
                        <li>Search the Web - Write a program that searches the web using DuckDuckGo and displays results.
                        </li>
                        <li>Encryption - Write a program that encrypts a string from user input, or file and is able to decrypt it as well.
                        </li>
                        <li>Command Line Game - Create a simple game that runs inside the terminal.
                        </li>
                </section>

                <section>
                    <h3>Let's Develop It Resources</h3>
                    <table>
                        <tr>
                            <td>Search the Web</td>
                            <td><a href="https://github.com/crazedpsyc/python-duckduckgo/">python-duckduckgo</a> library to get started. Download duckduckgo.py and put it in the same directory as your code. Use the query() function it provides to begin. (HINT: Results are often empty, but 'related' list usually has a few hits.)</td>
                        </tr>
                        <tr>
                            <td>Encryption</td>
                            <td>Read about the <a href="https://en.wikipedia.org/wiki/Caesar_cipher">Caesar Cipher</a> or find a similarly simple encryption mechanism online. You should find the ord() and chr() functions helpful, as well as the modulus operator '%'</td>
                        </tr>
                    </table>
                    <p>continued on next page...</p>
                </section>

                <section>
                    <h3>Let's Develop It Resources Continued</h3>
                    <table>
                        <tr>
                            <td>Command Line Game</td>
                            <td>This might be a text adventure with paragraphs of text followed by a series of choices for the user. A choice maps to another node in the story (another paragraph with choices). You might try storing the paragraphs separately in a text file. The format might be something different, such as a series of "rooms", each with a description, for the user to explore by entering commands such as "go west". Examples of these kinds of games are <a href="https://en.wikipedia.org/wiki/Colossal_Cave_Adventure">Colossal Cave Adventure</a> and <a href="https://en.wikipedia.org/wiki/Zor">Zork</a></td>
                        </tr>
                    </table>
                </section>

                <section>
                    <h3>Future Resources</h3>
                    <p></p>
                    <table>
                        <tr>
                            <td><a href="http://docs.python.org/2/">Python.org Documentation</a></td>
                            <td>Official Python Documentation</td>
                        </tr>
                        <tr>
                            <td><a href="http://www.greenteapress.com/thinkpython/html/index.html">Think Python</a></td>
                            <td>Online and print book with exercises.</td>
                        </tr>
                        <tr>
                            <td><a href="http://learnpythonthehardway.org/book/">Learn Python the Hard Way</a></td>
                            <td>Online and print book with exercises</td>
                        </tr>
                        <tr>
                            <td><a href="https://developers.google.com/edu/python/">Google's Python Class</a></td>
                            <td>Video lectures coupled with exercises</td>
                        </tr>
                        <tr>
                            <td><a href="http://newcoder.io/tutorials/">New Coder</a></td>
                            <td>Ideas for slightly larger projects and resources to get you started. Projects include accessing API's, scraping pages, writing IRC bots, and others.</td>
                        </tr>
                        <tr>
                            <td><a href="http://girldevelopit.com/">Girl Develop It</a></td>
                            <td>Local workshops, events, and coding sessions</td>
                        </tr>
                    </table>
                </section>

                <section>
                    <h3>Questions?</h3>
                </section>

                <section>
                  <h3>Upcoming Events</h3>
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                    <p>Feb. 24th &amp; 9th, 6:3pm - 9pm</p>
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                </section>

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