Keyword arguments in Python - Step-by-Step Execution

Concept Flow - Keyword arguments

Define function with parameters

↓

Call function with keyword arguments

↓

Match arguments to parameters by name

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Execute function body using matched values

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Return result

Keyword arguments let you call a function by naming each argument, so the order does not matter. The function matches values to parameters by their names.

Execution Sample

Python

def greet(name, age):
    print(f"Hello {name}, you are {age} years old.")

greet(age=30, name="Alice")

This code defines a function with two parameters and calls it using keyword arguments in a different order.

Execution Table

Step	Action	Parameter	Value	Output
1	Function greet defined	-	-	-
2	Call greet with age=30, name='Alice'	-	-	-
3	Match argument 'age' to parameter 'age'	age	30	-
4	Match argument 'name' to parameter 'name'	name	"Alice"	-
5	Execute print statement	-	-	Hello Alice, you are 30 years old.
6	Function greet ends	-	-	-

💡 Function completes after printing the greeting message.

Variable Tracker

Variable	Start	After Call
name	-	"Alice"
age	-	30

Key Moments - 2 Insights

Why can we pass arguments in any order when using keyword arguments?

Because keyword arguments match values to parameters by their names, not by position, as shown in execution_table rows 3 and 4.

What happens if we omit a required parameter when using keyword arguments?

Python will raise an error because the function expects all required parameters to be provided, even if using keywords.

Visual Quiz - 3 Questions

Look at the execution_table at step 3, what value is assigned to parameter 'age'?

A None

B 30

C "Alice"

D Error

💡 Hint

Check the 'Value' column at step 3 in the execution_table.

At which step does the function print the greeting message?

A Step 5

B Step 4

C Step 2

D Step 6

💡 Hint

Look for the step with output in the execution_table.

If we call greet(name="Bob") without age, what will happen?

A Function prints greeting with age as 0

B Function prints greeting with age as None

C Python raises an error for missing argument

D Function uses default age value

💡 Hint

Recall key_moments about missing required parameters.

Concept Snapshot

Keyword arguments let you call functions by naming parameters.
Order does not matter because matching is by name.
Syntax: func(param1=value1, param2=value2)
All required parameters must be provided.
Useful for clarity and flexibility.

Full Transcript

Keyword arguments in Python allow you to call a function by specifying the names of the parameters along with their values. This means you can pass arguments in any order, and the function will match them correctly by name. For example, calling greet(age=30, name="Alice") assigns 30 to age and "Alice" to name, even though the order is reversed. The function then uses these values inside its body. If you forget to provide a required parameter, Python will raise an error. This feature helps make function calls clearer and more flexible.

Practice

1. What is the main advantage of using keyword arguments when calling a function in Python?

easy

A. Keyword arguments make the function run faster.

B. You must provide arguments in the exact order defined in the function.

C. You can specify arguments by name, making the code clearer.

D. They allow you to skip required arguments.

Solution

1. Step 1: Understand keyword arguments

   Keyword arguments let you name the inputs when calling a function, so you don't have to remember the order.

2. Step 2: Compare options

   You can specify arguments by name, making the code clearer. correctly states that naming arguments makes code clearer. Options B, C, and D are incorrect because keyword arguments do not require order, do not affect speed, and cannot skip required arguments.

3. Final Answer:

   You can specify arguments by name, making the code clearer. -> Option C

4. Quick Check:

   Keyword arguments = clearer code [OK]

Hint: Keyword arguments name inputs, so order doesn't matter [OK]

Common Mistakes:

• Thinking keyword arguments must follow positional order
• Believing keyword arguments speed up the function
• Assuming keyword arguments can skip required parameters

2. Which of the following is the correct way to call the function def greet(name, age): using keyword arguments?

easy

A. greet(name='Alice', age=30)

B. greet('Alice', 30)

C. greet(age=30, 'Alice')

D. greet(name=30, age='Alice')

Solution

1. Step 1: Check keyword argument syntax

   Keyword arguments require the format parameter=value. greet(name='Alice', age=30) uses name='Alice' and age=30, which is correct.

2. Step 2: Identify errors in other options

   greet('Alice', 30) uses positional arguments only, which is valid syntax but does not use keyword arguments. greet(age=30, 'Alice') places positional argument after keyword, which is invalid syntax. greet(name=30, age='Alice') swaps types incorrectly.

3. Final Answer:

   greet(name='Alice', age=30) -> Option A

4. Quick Check:

   Keyword args = parameter=value pairs [OK]

Hint: Use parameter=value pairs for keyword arguments [OK]

Common Mistakes:

• Placing positional arguments after keyword arguments
• Swapping argument names and values
• Mixing types incorrectly in keyword arguments

3. What will be the output of the following code?

def info(name, age):
    print(f"Name: {name}, Age: {age}")

info(age=25, name='Bob')

medium

A. Name: 25, Age: Bob

B. Name: Bob, Age: 25

C. Name: , Age:

D. TypeError

Solution

1. Step 1: Understand keyword argument order

   Keyword arguments allow passing arguments in any order by naming them explicitly.

2. Step 2: Match arguments to parameters

   Here, age=25 and name='Bob' are passed, so name gets 'Bob' and age gets 25.

3. Final Answer:

   Name: Bob, Age: 25 -> Option B

4. Quick Check:

   Keyword args reorder inputs correctly [OK]

Hint: Keyword arguments can be in any order [OK]

Common Mistakes:

• Assuming order matters with keyword arguments
• Confusing parameter names with values
• Expecting errors when order is changed

4. Identify the error in the following function call:

def multiply(x, y):
    return x * y

result = multiply(x=5, 10)

medium

A. SyntaxError: positional argument after keyword argument

B. TypeError: missing required positional argument

C. No error, result is 50

D. NameError: variable not defined

Solution

1. Step 1: Check argument order rules

   In Python, positional arguments cannot come after keyword arguments in a function call.

2. Step 2: Analyze the call

   The call multiply(x=5, 10) has a keyword argument first, then a positional argument, which causes a syntax error.

3. Final Answer:

   SyntaxError: positional argument after keyword argument -> Option A

4. Quick Check:

   Positional args must come before keyword args [OK]

Hint: Positional arguments must come before keyword arguments [OK]

Common Mistakes:

• Placing positional arguments after keyword arguments
• Confusing error types for this syntax
• Assuming this call runs without error

5. Given the function def order(item, quantity=1, price=10):, which call correctly orders 3 items with a price of 15 each using keyword arguments?

hard

A. order('apple', 3, 15)

B. order(price=15, quantity=3)

C. order(quantity=3, 'apple', price=15)

D. order(item='apple', price=15, quantity=3)

Solution

1. Step 1: Understand function parameters and defaults

   The function has one required parameter item and two optional parameters quantity and price with defaults.

2. Step 2: Check each call for correctness

   order('apple', 3, 15) uses positional arguments only, which is valid but not keyword arguments. order(item='apple', price=15, quantity=3) uses keyword arguments for all parameters, correctly naming them in any order. order(quantity=3, 'apple', price=15) places positional argument after keyword argument, which is invalid. order(price=15, quantity=3) misses the required item argument.

3. Final Answer:

   order(item='apple', price=15, quantity=3) -> Option D

4. Quick Check:

   Keyword args can be in any order, all required given [OK]

Hint: Use all required keywords, order doesn't matter [OK]

Common Mistakes:

• Omitting required arguments
• Placing positional after keyword arguments
• Using positional only when keyword is asked