Introducing Pyramid: The Ultimate Versatile Web Framework

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from wsgiref.simple_server import make_server
from pyramid.config import Configurator
from pyramid.response import Response

def hello_world(request):
    return Response('Hello, Pyramid!')

if __name__ == '__main__':
    with Configurator() as config:
        config.add_route('home', '/')
        config.add_view(hello_world, route_name='home')
        app = config.make_wsgi_app()
    
    server = make_server('0.0.0.0', 6543, app)
    server.serve_forever()

This example sets up a basic Pyramid application with routing and a simple view. The hello_world function returns a basic response, demonstrating how straightforward it is to get started with Pyramid.

// C subroutine
#include <stdio.h>

// Function to calculate the square of a number
int square(int num) {
    return num * num;
}

# bash command to compile C subroutine into shared library
gcc -shared -o libsquare.so -fPIC square.c

# Python code that calls C subroutine by loading shared library
from ctypes import cdll, c_int

# Load the shared library
lib = cdll.LoadLibrary('./libsquare.so')

# Set the argument and return types
lib.square.argtypes = [c_int]
lib.square.restype = c_int

# Call the C function from Python
result = lib.square(4)
print(f"The square of 4 is {result}.")

Python code running C subroutine:

# Context Manager
class FileCloser:
    def __init__(self, filename):
        self.filename = filename
    
    # Code that is executed right after the with 
    # statement
    def __enter__(self):
        self.file = open(self.filename, 'r')
        return self.file
    
    
    # Code that is executed right after the code block 
    # is executed
    def __exit__(self, exc_type, exc_val, exc_tb):
        self.file.close()
        
        
# Using Context Manager
with FileCloser('myfile.txt') as f:
    # Your code here
    pass

Text

Example of Context Managers in Python

Consistency does win the race when it comes to becoming a senior engineer.

The journey from a junior to a senior developer is paved with continuous learning and curiosity.

Staying abreast of the latest trends, tools, and technologies is crucial in the fast-evolving tech landscape.

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Nothing is more trustworthy than an engineer with a track record of delivering projects on time.

The best engineers do one thing very well:

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Clear communication demystifies technology, fostering collaboration and innovation across teams.

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from collections import defaultdict

# Initialize the defaultdict
word_count = defaultdict(int)

# Efficiently count occurrences of each word
words = ['apple', 'banana', 'apple', 'pear']
for word in words:
    word_count[word] += 1

Python Tip:

Use the standard library whenever you can

Intro to React

INFO 253A: Frontend Web Architecture

Kay Ashaolu

Now it is time to learn React

You now have a better handle of JavaScript
It's time now to learn a new way of developing UI in the browser (and beyond)
Note: there are other extensions to React (e.g. React 360)

Review: React is a library

React is a JavaScript library for building user interfaces
Build declarative components based on the current state of your application
Differs from the Event Driven approach we have been doing so far

Example, Event Driven App

Lets say you have an array of strings, each representing the subject of a todo
And the HTML code was rendered as follows

<ul id="todos">
	<li>Task 1</li>
	<li>Task 2</li>
</ul>

Example, Event Driven App

If you wanted to add a new task on a click of a button, what would you do?
If you wanted to delete a task on a click of the task, what would you do?

Example, Event Driven App

To add a new task, you would have to select the #todos ul, and then manipulate the html so that there is a new li at the end of the list
To delete a new task you would need to find the right li and delete that from the tree

Example, Event Driven App

This is doable, but there are some things to consider:
- What happens if there are multiple todo lists in a single page?
- What happens if the user tries to add and delete a task at the same time?

Events add up

You will need to take several precautions to ensure that each todo list is completely independent and that events do not collide with each other
This is not trivial to do for large systems

React: a different approach

React uses a declarative programing paradigm
Instead of worrying about every action that could happen with your list, you first define what your todo list would look like, given an array of strings.
You create a component using your above defintion containing state that contains the titles of all of the tasks
On click events, you modify this internal state and the component will update itself

Lets then learn React

At this point your browser will not understand your code
Reason 1: some browsers do not understand ES6 JavaScript
Reason 2: some React syntax is not valid JavaScript

Let's set up your environment

Install NodeJS on your computer
Follow these steps from Create React App

About your dev server

The NodeJS server you installed uses NodeJS, Babel, and Webpack, as well as the React codebase to bundle all of your source Javascript in a single file
The NodeJS server also builds your single HTML page, as well as keeps a development server running to reload any changes

So without further ado, let's get into React!

Hello World

src/index.js

import React from "react";
import ReactDOM from "react-dom";

const jsx_element = <h1>Hello, world!</h1>;
const dom_element = document.getElementById('root');
ReactDOM.render(jsx_element, dom_element);

Hello World Explained: index.html

Your index.html file is an empty file that contains one empty div in the body section
Note that the empty div's id is "root"
This div is the entry point for our react app: we will tell React in our script to replace this div with our react application
This html file will largely remain unchanged

Hello World Explained: index.js

We are first importing the React and ReactDOM packages into our JavaScript
Next we are telling ReactDOM to render given:
1. The content of your website
2. What element in your index.html file that will house your React App

Hello World Explained: JSX

JSX stands for JavaScript XML
JSX is an extension of JavaScript that enables you to write HTML like syntax directly in your Javascript
This enables the ability to write HTML templates directly into your JavaScript code
You can also embed expressions, variables, and properties directly into JSX

Example

src/index.js

let formatName = (user) => {
  return user.firstName + ' ' + user.lastName;
}
const user = {
  firstName: 'Harper',
  lastName: 'Perez'
};
const element = (
  <h1>
    Hello, {formatName(user)}!
  </h1>
);
ReactDOM.render(
  element,
  document.getElementById('root')
);

Example explained

Note: the index.html has not changed. To use React for your entire app, you can define a single div in the body that is React's entry point
We defined a function called formatName that takes a object that has two properties: a firstName and a lastName
The formatName function returns a single string with both of those elements
We use this function 'formatName' inside of our JSX code (the const element)
This shows how you can use these properties within your JSX code

Why JSX?

Remember separating content from presentation?
Separating HTML (content) from CSS (presentation) is core to the web
However once we start using JavaScript, we have the ability to change the HTML rendered on the page
That means HTML code can possibly be throughout our JavaScript codebase
JSX gives us the ability to write out templated HTML code in a very intuitive fashion

Another Example

src/index.js

import React from "react";
import ReactDOM from "react-dom";

function tick() {
  const element = (
    <div>
      <h1>Hello, world!</h1>
      <h2>It is {new Date().toLocaleTimeString()}.</h2>
    </div>
  );
  ReactDOM.render(element, document.getElementById('root'));
}
setInterval(tick, 1000);

Wait, what?

Every call to ReactDOM.render tells React to re-render elments given the data that it currently has
The code setInterval(tick, 1000) is a special function that tells JavaScript to execute the tick function every 1000 millliseconds.
The tick function then defines the element and passes in its properties (namely {new Date().toLocaleTimeString()}) before that components is rendered
This is why you see the clock ticking every second

Components

This is one of the things I like the most about React
The focus on components as independent, resusable pieces that can be placed anywhere
This uses the composability relationship: each element can be composed by other elements

Components

Using a combination of JSX and JavaScript, you can bundle look and feel and functionality in a single JavaScript class
You can consider these React Elements and HTML Elements that you can place wherever you like
Let's get into the anatomy of a Component

Component Example

import React from "react";
import ReactDOM from "react-dom";

function FormatName(props) {
	return (
      <h1>
        Hello, {props.firstName} {props.lastName}!
      </h1>
    );
}

ReactDOM.render(
  <FormatName firstName="Kay" lastName="Ashaolu" />,
  document.getElementById('root')
);

Component Example Explained

We are creating a component by creating a function
The name of the function (i.e. FormatName) is the name of the element
The React library takes that function and creates a component out of it that can be used

Props

A parameter called props is passed into this function
props is an object that contains all of the attributes and values that are passed into the element

Component Instance Properties

When you add the attribute firstName="Kay", this props object will have a key named "firstName"
And a value named "Kay"
These properties are immutable

<FormatName firstName="Kay" lastName="Ashaolu" />,

Return

What the function returns is the "html" that is generated by the component
This function is executed and the "html" is generated in a number of areas in react (e.g. on a call on ReactDOM.render())
This function returns JSX code that the component would render into

Intro to React

Now it is time to learn React

Review: React is a library

Example, Event Driven App

Example, Event Driven App

Example, Event Driven App

Example, Event Driven App

Events add up

React: a different approach

Lets then learn React

Let's set up your environment

About your dev server

So without further ado, let's get into React!

Hello World

Hello World Explained: index.html

Hello World Explained: index.js

Hello World Explained: JSX

Example

Example explained

Why JSX?

Another Example

Wait, what?

Components

Components

Component Example

Component Example Explained

Props

Component Instance Properties

Return

Questions?

Copy of Copy of Intro to React - Frontend Webarch

Copy of Copy of Intro to React - Frontend Webarch

kayashaolu

Intro to React

Now it is time to learn React

Review: React is a library

Example, Event Driven App

Example, Event Driven App

Example, Event Driven App

Example, Event Driven App

Events add up

React: a different approach

Lets then learn React

Let's set up your environment

About your dev server

So without further ado, let's get into React!

Hello World

Hello World Explained: index.html

Hello World Explained: index.js

Hello World Explained: JSX

Example

Example explained

Why JSX?

Another Example

Wait, what?

Components

Components

Component Example

Component Example Explained

Props

Component Instance Properties

Return

Questions?

Copy of Copy of Intro to React - Frontend Webarch

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