Quark’s Outlines: Python Code Blocks

Synopsis of Python Code Blocks

What is a code block?

A code block is a group of lines of code that go together. The computer reads this block from top to bottom and follows each line in turn. You can think of a code block as a small chunk of work the computer will do at once. All code blocks follow a sequence, one step after another.

All code blocks run in order. The structured programming theorem published by Corrado Böhm and Giuseppe Jacopini in 1966 showed that any program can be made with three simple patterns: sequence, choice, and loops. At the heart of every code block is a list of steps the computer follows in sequence.

What does “code block” mean in Python?

In Python, a code block is any group of Python instructions that are run as one piece. Python treats these blocks as units of work. A module is a file with lines of Python code — this file is seen by Python as one code block. A script is also a code block, run from start to finish. A function is a block that runs when called. A class is a block that gives a pattern for making objects. Even a single line you type into the Python shell is a code block. Text passed to exec() or eval()also becomes a code block that Python runs.

How does Python run a code block?

Python runs each block inside something called a frame. A frame keeps track of names and what they point to. Names are words used in code that stand for numbers, strings, or other things. First, Python looks for a name inside the block (local). If it does not find it there, Python looks outside the block (global). If it still does not find the name, it checks built-in names. If the name is not found anywhere, Python stops and shows a NameError.

Why learn about code blocks in Python?

Learning about code blocks helps you write neat, clear programs. You can write a block once and use it many times. Small blocks fit together to build big, strong programs. Code blocks make your work easier to read, test, and grow.

Timeline of Python Code Blocks

Where do code blocks come from?

Code blocks help people write clear, sequential instructions to machines. Before computers, people used blocks of instructions to play music, weave cloth, and count numbers. Over many years, different tools used clear blocks to store instructions. Each new idea made these blocks clearer and easier to use. The following timeline shows important inventions and ideas. Each step led toward the structured code blocks we use today, including the blocks used in Python programming.

Early Forms of Code Blocks

850 – Banū Mūsā Music Box. Cylinders used ordered pins as blocks of notes.

1386 – Salisbury Cathedral Clock. Mechanical drums used blocks to ring bells in order.

1725 – Bouchon Loom. Basile Bouchon's punched paper tape stored weaving steps in ordered blocks.

1801 – Jacquard Loom. Joseph Jacquard's loom used punched cards as blocks of weaving instructions.

1842 – Debain Player Piano. Alexandre Debain’s piano used blocks of punched holes for ordered notes.

1887 – Hollerith Census Machine. Herman Hollerith’s machine counted census data from blocks of punched cards.

1906 – De Forest Audion Tube. Lee de Forest’s vacuum tubes managed electric signals in ordered blocks.

1919 – Eccles-Jordan Flip-Flop. Eccles and Jordan’s circuits stored data clearly in blocks of signals.

Well-Known Writings About Code Blocks

1936 – Turing Machine. Alan Turing (Proc. London Math. Soc.) described simple computing steps in ordered blocks.

1936 – Church’s Logic Blocks. Alonzo Church (Amer. Journal of Mathematics) showed logic solved by ordered steps.

1966 – Böhm-Jacopini Theorem. Corrado Böhm and Giuseppe Jacopini (Comm. ACM) proved all programs made of sequence, choice, loop.

Commercial Implementations of Code Blocks

1950 – IBM FORTRAN. IBM introduced clearly reusable code blocks into computer programming.

1964 – Dartmouth BASIC. John Kemeny and Thomas Kurtz used easy-to-read code blocks for beginners.

1972 – Ritchie’s C Language. Dennis Ritchie (Bell Labs) introduced { } braces for marking code blocks.

History of Python Code Blocks

1989 – Python 0.9 Indentation. Guido van Rossum used spaces clearly to mark code blocks.

1994 – Python 1.0 Lambda. Added short code blocks called lambdas for quick tasks.

2000 – Python 2.0 List Blocks. Introduced clear, short list blocks for easy data handling.

2008 – Python 3.0 Text Handling. Improved code blocks for clearer handling of words and numbers.

2016 – Python 3.5 Async Blocks. Added clear code blocks to do many tasks at once.

2018 – Python 3.7 Data Classes. Added clear code blocks for easy storage of data.

2023 – Python 3.12 Type Checks. Improved checks inside code blocks to avoid mistakes.

2025 – Python 3.13 Name Checks. Improved name checks in code blocks to make code safer.

Problems & Solutions with Python Code Blocks

Python code blocks help you do tasks and solve everyday problems. You can use Python code blocks to store information, repeat actions, or quickly check numbers.

In this section, you will see common problems people have. Each problem has a solution using Python code blocks. These examples show how Python code blocks work in daily life.

Problem 1: How to keep shared information in one place using a Python module code block

Problem:

You run a bakery. You have prices for items and want to use these prices in different systems without typing them again.

Solution:

With Python, you can create a module to keep information in one file. A module is a code block you save and import into other programs so you can reuse the same data.

prices = {
    "apple": 0.75,
    "milk": 2.50,
    "bread": 3.00
}

def get_price(item):
    return prices.get(item, "Item not found")

In another program, you can write:

import prices

print(prices.get_price("milk"))
print(prices.get_price("banana"))

Problem 2: How to run saved instructions using a Python script code block

Problem:

You run a clothing store. There is a screen connected to a computer. Each morning, you want the computer to show a welcome message without typing it every time.

Solution:

Python lets you use a script file to run saved instructions. A script is a code block that Python reads line by line and runs when you start it.

print("Welcome to our clothing store! Have a great shopping day.")

You can run this by typing in the terminal:

python welcome.py

Problem 3: How to do quick checks using Python interactive command code blocks

Problem:

You are counting cash at the register. You need to add numbers quickly without writing a file.

Solution:

With Python, you can open the interactive shell and type commands one by one. Each command is a code block that runs right after you press Enter.

In the Python shell, you can type:

print(200 + 75)

Python will show the result right away.

Problem 4: How to make reusable templates using a Python class code block

Problem:

You manage a library. Each book has a title and an author. You want a simple way to store this information and reuse it for many books.

Solution:

Python lets you use a class to build a reusable template. A class is a code block where you define how each object should hold its data and actions.

class Book:
    def __init__(self, title, author):
        self.title = title
        self.author = author

    def info(self):
        return f"{self.title} by {self.author}"

You can create a book and show its information like this:

b = Book("Charlotte's Web", "E. B. White")
print(b.info())

Problem 5: How to repeat the same calculation using a Python function code block

Problem:

You work in a smoothie shop. You need to multiply the price of one smoothie by the number of smoothies ordered.

Solution:

With Python, you can write a function to repeat calculations. A function is a code block that runs whenever you call it with new numbers.

def total_price(price_per_smoothie, quantity):
    return price_per_smoothie * quantity

You can use the function with this example:

print(total_price(4.25, 3))

Problem 6: How to run text as code using a Python exec code block

Problem:

You run an education website. Students type math problems in text form. You need to solve them and show the answer.

Solution:

Python lets you use the exec function to run text as code. That text becomes a code block, and Python runs it and stores the result for you to use.

student_code = "result = (7 + 3) * 4"
global_space = {}
local_space = {}

exec(student_code, global_space, local_space)

You can show the result with:

print(local_space["result"])

Problem 7: How to solve formulas from text using a Python eval code block

Problem:

You help people plan budgets. They type formulas like "income minus rent minus food." You need to use their numbers and show them the answer.

Solution:

With Python, you can use eval() to solve formulas from text. The formula becomes a code block, and Python uses your numbers to find the result.

data = {'income': 3000, 'rent': 1200, 'food': 500}
formula = "income - rent - food"

result = eval(formula, data)

You can print the answer with:

print(f"Money left: ${result}")

Problem 8: How to run code from another file using Python execfile code blocks (Python 2)

Problem:

You work in a delivery company. You have a file that calculates delivery prices. You want to run that file inside another program without copying the code.

Solution:

With Python 2, you can use execfile() to run code from another file. That file becomes a code block, and Python runs it in your current program’s space.

execfile("delivery_prices.py")

In Python 3, you can open the file and run the code like this:

with open("delivery_prices.py") as f:
    exec(f.read())

Problem 9: How to check answers typed by users using a Python input code block

Problem:

You are making a math quiz game. Players type their answers as math formulas. You need to solve the formula and check if the answer is correct.

Solution:

Python lets you use input() to read answers as text and eval() to solve them. The text becomes a code block that Python runs to find the answer.

question = "What is 6 * 7? "
answer = input(question)

You can check the result with:

if eval(answer) == 42:
    print("Correct!")
else:
    print("Try again.")

What Do You Think About Python Code Blocks?

• What do you think about Python code blocks?

• How do you remember the syntax for code blocks?

• Do you prefer curly braces? Or indentations for code blocks?

Leave a comment below!

Mike Vincent is an American software engineer and writer based in Los Angeles. Mike writes about technology leadership and holds degrees in Linguistics and Industrial Automation. More about Mike Vincent