Does Python 3.10 have match?

Does Python 3.10 have match?

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Yes, Python 3.10 does come with a new feature called "match-case" statement. The match statement is used with the case statements to specify alternative patterns to be matched against the subject.

Before Python 3.10, you could use the if-elif-else construct to achieve similar results, but with the introduction of match, the code becomes more concise and expressive.

Here's an example of how you might use it:

def shape_area(shape):
match shape:
case "circle":
radius = 4
return 3.14 * (radius ** 2)
case "rectangle":
length, width = 4, 3
return length * width
case _:
return "Unknown shape"
print(shape_area("circle"))  # Outputs: 50.24
print(shape_area("rectangle"))  # Outputs: 12
print(shape_area("triangle"))  # Outputs: Unknown shape

In this example, we define a function shape_area that takes a string representing the shape of an object. The function uses a match statement to determine which shape it is and then returns the area of that shape.

The case statements specify patterns to match against, and each pattern is evaluated in order until one matches. If none do, the _ pattern (which matches everything) is used as a catch-all.

Python's match statement also supports guard clauses, which allow you to add conditions to ensure that a particular branch is only taken if certain criteria are met:

def shape_area(shape):
match shape:
case "circle" if radius > 0:
return 3.14 * (radius ** 2)
case "rectangle":
length, width = 4, 3
return length * width
case _:
return "Unknown shape"
print(shape_area("circle"))  # Error! No radius defined.

In this example, we've added a guard clause to the "circle" branch, which checks if radius is greater than zero. If it's not, the branch won't be taken.

The match statement can also be used with tuples and dictionaries:

def process_data(data):
match data:
case {"x": _, "y": _}:
print(f"Data point at ({data['x']}, {data['y']})")
case {"name": _, "age": _}:
print(f"Person: {data['name']} is {data['age']} years old.")
case _:
print("Unknown data format")
process_data({"x": 1, "y": 2})
process_data({"name": "John", "age": 30})

In this example, we define a function process_data that takes a dictionary and uses the match statement to determine what kind of data it is.

Python's match statement provides a concise way to handle multiple patterns and can be particularly useful when working with complex data structures.

Is Python match faster than if?

I'd be happy to provide an answer in English!

Python's match statement is a relatively new feature introduced in Python 3.10, and it has sparked interest among developers about its performance compared to traditional if-elif-else statements.

In general, the match statement is designed to make pattern matching more concise and readable, allowing you to handle different cases based on patterns. It's often used with advanced features like type hints or enums. When it comes to performance, Python's interpreter is designed to optimize away redundant checks in if-elif-else chains. This means that if the conditions are simple and don't involve complex computations, both match and if-elif-else will likely have similar performance.

However, when the conditions involve complex computations or recursive calls, the performance difference can become significant. Python's interpreter has to recursively traverse the conditionals in an if-elif-else chain, whereas the match statement allows the interpreter to use a more direct lookup mechanism, reducing overhead and making it potentially faster.

To give you a rough estimate, let's consider some simple examples:

Example 1: Simple pattern matching

x = "hello"
result = None
if x == "hello":
result = "Matched!"
elif x == "goodbye":
result = "Not hello"
print(result)  # Output: Matched!

In this case, both match and if-elif-else would likely have similar performance, as the conditions are simple and don't involve complex computations.

Example 2: Complex computation in pattern matching

x = "hello"
result = None
if x == "hello":
y = compute_complex_value()
if y > 5:
result = "Matched!"
elif x == "goodbye":
result = "Not hello"
print(result)  # Output: Matched!

In this case, the performance difference between match and if-elif-else can be noticeable. The if-elif-else chain would require more recursive traversals to evaluate the conditions, whereas the match statement could potentially optimize away some of these overheads.

It's worth noting that Python's match statement is still relatively new, and there might be edge cases where performance differences become more significant. In general, if you're working with simple, straightforward conditions, both match and if-elif-else will likely have similar performance. However, when dealing with complex computations or recursive calls, the match statement could offer a performance advantage.

Hope this answer meets your expectations!