Python3中exec()的反向操作是什么？如何打印表达式列表的字符串与求值结果？

If you want to display both the string form of expressions and their computed results, there are two straightforward approaches depending on how you prefer to define your expressions.

Approach 1: Store expressions as strings #

This is the most direct method—save your expressions as strings, loop through them, evaluate each with eval(), and print both the expression and its result:

expressions = [
    "10 + 25 * 2",
    "len('Python is awesome')",
    "round(3.14159 * 2, 2)",
    "max([4, 12, 7, 21]) - min([4, 12, 7, 21])"
]

for expr in expressions:
    result = eval(expr)
    print(f"{expr} = {result}")

Running this will output:

10 + 25 * 2 = 60
len('Python is awesome') = 17
round(3.14159 * 2, 2) = 6.28
max([4, 12, 7, 21]) - min([4, 12, 7, 21]) = 17

Approach 2: Use lambdas to avoid string quotes #

If you’d rather write actual Python expressions instead of wrapping them in strings, you can wrap each expression in a lambda and use inspect.getsource() to extract the expression text:

import inspect

def print_expr_with_result(expr_func):
    # Extract the expression from the lambda's source code
    source = inspect.getsource(expr_func).strip()
    # Clean up the lambda wrapper to get just the expression
    expr = source.split(':')[-1].strip()
    # Evaluate and print
    result = expr_func()
    print(f"{expr} = {result}")

# Usage: wrap each expression in a lambda
print_expr_with_result(lambda: 10 + 25 * 2)
print_expr_with_result(lambda: len('Python is awesome'))
print_expr_with_result(lambda: round(3.14159 * 2, 2))
print_expr_with_result(lambda: max([4, 12, 7, 21]) - min([4, 12, 7, 21]))

This gives the same output as the first approach, but you don’t have to quote your expressions. The only tradeoff is the extra lambda wrapper, which is a small price for readability.

内容的提问来源于stack exchange，提问作者user5960761