Expression Parser with Antlr4

An Antlr4-Based Expression Parser

Lou Mauget Articles, Development Technologies & Tools, Java, Programming, Python 1 Comment

In this blog, we’ll present a simple arithmetic expression parser implemented through an Antlr4 parser generator. It will be able to take in an input string (such as 2+4+-4+-2*10%9*7) to produce the result (-12.0).

You may be thinking, “Great, but what’s the point?” Well, to answer your question, as simple as this example may seem, the principles involved actually extend to use cases such as DSLs, transpilation, and anything else expressible by grammar rules.

This post has two parts. In part 1, we’ll discuss the background components of a parser. In part 2, we’ll cover building the demo and running it. If you already understand grammar parsing, you could skip part one.

A Vue of Python

Chris Berry Articles, Development Technologies & Tools, JavaScript, Node.js, Python, Vue.js Leave a Comment

Earlier this year I blogged about creating a Lean Mean Vue Machine called Quotes on Demand. The application was a fully featured CRUD application served from a NodeJS server and had a self contained VueJS front end.

But wouldn’t it be a nice test to see if that same Vue application could switch over to another API, say something like a Python web server powered by Flask?

In this post, we will create a Python web application that will have 100% parity to an existing NodeJS web application. This will enable an existing VueJS front end to connect to the application with no additional code changes in the user interface code.

How to Create a Dystopian Future at Home with Python, OpenCV, and Microsoft Azure

Derek Andre Articles, Azure, Cloud, Development Technologies & Tools, Python, Tutorial 2 Comments

Facial recognition is both amazing and horrifying. Some amazing things it can do is the ability to find missing children or seniors, using your face to unlock your phone, and being able to board an airplane faster.

In this blog post, I want to highlight some powerful tools and platforms that allow you to create distributed facial recognition systems with OpenCV and Azure’s Cognitive Services. By the end of this post, you will have a working face detector using OpenCV that can communicate with Azure’s Cognitive Services.

I used Python 3.7.4 and pip 19.2.3 for this project. You can view the code from this blog at https://github.com/dcandre/Dystopian-Future-At-Home.

Using Docker + AWS to Build, Deploy and Scale your App

Brandon Klimek Articles, AWS, Cloud, DevOps, Docker, Python, Spring, Spring Boot, Tutorial 8 Comments

I recently worked to develop a software platform that relied on Spring Boot and Docker to prop up an API. Being the only developer on the project, I needed to find a way to quickly and efficiently deploy new releases. However, I found many solutions overwhelming to set up.

That was until I discovered AWS has tools that allow any developer to quickly build and deploy their application.

In this 30 minute tutorial, you will discover how to utilize the following technologies:
– AWS CodeCommit – source control (git)
– AWS Code Build – source code compiler, rest runner
– AWS Codepipeline – builds, tests, and deploys code every time the repo changes
-AWS Elastic Beanstalk – service to manage EC2 instances handling deployments, provisioning, load balancing, and health monitoring
-Docker + Spring Boot – Our containerized Spring Boot application for the demo

Once finished, you will have a Docker application running that automatically builds your software on commit, and deploys it to the Elastic beanstalk sitting behind a load balancer for scalability. This continuous integration pipeline will allow you to worry less about your deployments and get back to focusing on feature development within your application.