decorators.py

# simpler case of decorators
# memoization with decorator
def memoize(func):
    cache = {}

    def wrapper(*args, **kwargs):
        if args not in cache:
            cache[args] = func(*args, **kwargs)
        return cache[args]

    return wrapper


@memoize
def build_tree(depth):
    """Builds a tree of a given depth."""
    if depth == 0:
        return []
    return ['leaf %d' % depth, *build_tree(depth - 1)]


print(build_tree(5000))

# ---------------------------------------------------------
# more complicated case of decorators
# call limit
import time


def once_in(num_secs):
    def middle(func):
        last_invoked = 0

        def wrapper(*args, **kwargs):
            nonlocal last_invoked
            elapsed = time.time() - last_invoked
            if elapsed < num_secs:
                raise Exception('Only %f seconds passed' % elapsed)
            last_invoked = time.time()
            return func(*args, **kwargs)

        return wrapper

    return middle


@once_in(40)
def log_branch_diagnostics(logfile, branch_no, status):
    """Logs diagnostics for the given branch."""
    delimiter = '\n'
    with open(logfile, 'a+') as f:
        f.write('Branch %d: %s%s' % (branch_no, status, delimiter))


log_branch_diagnostics('lf.log', 32, 'OK')