How to preserve and view keywords in Python

1. What are reserved keywords

Reserving keywords are vocabulary with special meanings and functions in the Python language, and these vocabulary form the grammatical basis of Python. They cannot be redefined or used as identifiers such as variable names and function names. They assume important responsibilities in the code such as controlling program logic and defining data structures.

2. View retained keywords

Execute in the Python interactive command line:

import keyword
print()

Output result (Python 3.10+):

['False', 'None', 'True', 'and', 'as', 'assert', 'async', 'await', 
 'break', 'class', 'continue', 'def', 'del', 'elif', 'else', 
 'except', 'finally', 'for', 'from', 'global', 'if', 'import', 
 'in', 'is', 'lambda', 'nonlocal', 'not', 'or', 'pass', 'raise', 
 'return', 'try', 'while', 'with', 'yield']

3. Detailed explanation of core keywords (categorized by function)

Control structure class

1. Conditional control

if x > 5:
    print("Greater than 5")
elif x == 5:
    print("Equal to 5")
else:
    print("less than 5")

2. Circulation control

# for loopfor i in range(3):
    print(i)

# while loopcount = 0
while count < 3:
    print(count)
    count += 1

​​​​​​​# Loop controlfor num in [1, 2, 3, 4]:
    if num % 2 == 0:
        continue  # Skip even numbers    if num > 3:
        break    # Terminate the loop    print(num)

Logical operators

print(True and False)  # Output Falseprint(True or False)   # Output Trueprint(not True)        # OutputFalse

Special value

result = None
is_valid = True
max_value = float('inf')

Functions and classes

def greet(name):
    return f"Hello, {name}!"

class Animal:
    def __init__(self, species):
         = species

    def speak(self):
        raise NotImplementedError

Exception handling

try:
    1 / 0
except ZeroDivisionError:
    print("Can't be divided by zero!")
finally:
    print("Cleaning Operation")

Context Management

with open('') as file:
    content = ()
# Files are automatically closed

Other important keywords

#Asynchronous programmingasync def fetch_data():
    await api_request()

# Placeholderdef todo():
    pass  # To be implemented
# Scope Controlglobal_var = 10
def modify():
    global global_var
    global_var = 20

4. Common error examples

# Error: Use keywords as variable nameclass = "Computer Science"  # SyntaxError
def = 10                   # SyntaxError

​​​​​​​# Error: Incorrect use isa = [1,2,3]
b = [1,2,3]
print(a is b)  # False (Compare object identity)print(a == b)  # True （Compare values）

V. Best Practices

IDE syntax highlighting function to identify keywords

Variable naming avoids vocabulary in use

Add underscore if necessary: ​​class_ = ‘MyClass’

Pay attention to version changes (such as async/await added in Python 3.7)

6. Advanced tips

• yield is used for generator functions
• nonlocal is used for variable modification in closures
• lambda creates anonymous functions
• del Delete object reference

Mastering these reserved keywords is the only way to become a Python developer. It is recommended to deepen your understanding through actual coding exercises. When encountering errors, please check whether keywords have been misused.

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