Functions: return vs yield

• Regular functions execute immediately, run to completion, and return a single value (or None).
• Generator functions return an iterator immediately; their body runs incrementally as values are requested.
• Understanding this distinction is critical for choosing between eager and lazy workflows.

Regular Function (return) Recap

• Calling a regular function runs its entire body before returning.
• A single return exits the function and discards all local state.
• Useful when you need to compute and return a complete result at once.

def get_list_of_servers():
    print("Regular function started.")
    servers = []

    for i in range(3):
        server_name = f"server-{i}"
        print(f"\tAdding {server_name}")
        servers.append(server_name)

    print("Regular function finished.")

    return servers

servers = get_list_of_servers()
print(f"Returned list: {servers}")

Generator Function (yield) Recap

• Calling a generator function returns a generator object without running its body.
• Each yield returns one value and pauses, preserving local variables until the next request.
• Ideal for producing sequences lazily, especially when the full list is large or unbounded.

def yield_servers(count):
    print("Generator function started.")

    for i in range(count):
        server_name = f"server-{i}"
        print(f"\tYielding {server_name}")
        yield server_name

    print("Generator function finished.")

servers_gen = yield_servers(3)

for server in servers_gen:
    print(f"Server received: {server}")