cache ⚡, decorator 🖌️, binary 🧮, SQLite ⛁

Techletter #87 | August 24, 2024

What is enumerate in Python?

The enumerate() function in Python is a built-in function that simplifies the process of iterating over a collection while keeping track of the index of each item.

fruits = ['apple', 'banana', 'cherry']
for index, value in enumerate(fruits):
    print(index, value)

How to use cache in Python?

Caching in Python is a technique used to store frequently accessed data in a temporary location to improve application performance.

from functools import cache

@cache
def compute_square(n):
    return n * n

print(compute_square(5))  # Calculating square of 5...
print(compute_square(5))  # Cached result

What is the use of a decorator in Python?

A decorator in Python is a function that modifies the behavior of another function.

def simple_decorator(func):
    def wrapper():
        print("1")
        func()
        print("3")
    return wrapper

@simple_decorator
def say_hello():
    print("Hello!")

say_hello()

How do you get the binary number from an integer?

In JavaScript

const binary = num.toString(2); // output 101

In python

binary = bin(num)[2:] #output: 101

# if you don't use [2:]
# you will get 0b101

How to use SQLite in your node project?

Basically, I got to know about SQLite while I was working on Python Django. So, here is how you can integrate SQLite into your node projects:

The complete code can be found here

import sqlite3_package from "sqlite3";
import * as uuid from "uuid";

const sqlite3 = sqlite3_package.verbose();

class DB {
    constructor() {
        this.db = new sqlite3.Database(":memory:", (error) => {
            if (error) {
                console.log("Error while connecting to the sqlite db", error.message);
            }
            console.log("connected to sqlite database");
        });

        this.db.serialize(() => {
            this.db.run(`CREATE TABLE IF NOT EXISTS process_info (
                id INTEGER PRIMARY KEY,
                uuid BLOB NOT NULL,
                step INTEGER,
                message TEXT
            )`);
        });

        this.insert = this.db.prepare(`INSERT INTO process_info (uuid, step, message) VALUES(?, ?, ?)`);
        this.insert.run(uuid.v4(), 1, "List fetched");
    }

    getProcessInfo = (requestId) => {
        return new Promise((resolve, reject) => {
            this.db.all(`SELECT * FROM process_info WHERE uuid="${requestId}"`, [], (err, rows) => {
                if (err) {
                   reject(err);
                }
                resolve(rows);
            });
        });
    }

    addProcessInfo = (requestId, step, message) => {
        return new Promise((resolve, reject) => {
            this.insert.run(requestId, step, message, (err) => {
                if (err) {
                    reject(err);
                }
                resolve(true);
            });
        })
    }
}

const DbInstance = new DB();
export {
    DbInstance
}