Flask<1>--Decorator

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Since Flask uses route() decorator to bind a function to a URL (Routing), this blog gives naive decorators and its corresponding code without decorator.

Level 1 (no parameters)

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def wrapper(func):
    def inner():
        print("start")
        func()
        print("end")
    return inner


def log():
    print("logging")


log = wrapper(log)
log()

Corresponding decorator :

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def wrapper(func):
    def inner():
        print("start")
        func()
        print("end")
    return inner
    
    
@wrapper
def log():
    print("logging")


log()

output:
start
logging
end

Level 2 (require parameter for log)

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def wrapper(func):
    def inner(file_name):
        print("start")
        func(file_name)
        print("end")
    return inner


def log(file_name):
    print("logging " + file_name)


log = wrapper(log)
log('file')

Corresponding decorator :

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def wrapper(func):
    def inner(file_name):
        print("start")
        func(file_name)
        print("end")
    return inner
    
    
@wrapper
def log(file_name):
    print("logging " + file_name)


log('file')

output:
start
logging file
end

Level 3 (Require parameter for decorator)

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def wrapper(path_name):
    def decorator(func):
        def inner():
            print("start logging in " + path_name)
            func()
            print("end")
        return inner
    return decorator


def log():
    print("logging")


log = wrapper('path')(log)
log()

Corresponding decorator:

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def wrapper(path_name):
    def decorator(func):
        def inner():
            print("start logging in " + path_name)
            func()
            print("end")
        return inner
    return decorator


@wrapper("path")
def log():
    print("logging")


log()

output:
start logging in path
logging
end

Level 4 (Require parameter for decorator&log)

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def wrapper(path_name):
    def decorator(func):
        def inner(file_name):
            print("start logging in " + path_name)
            func(file_name)
            print("end")
        return inner
    return decorator


def log(file_name):
    print("logging " + file_name)


log = wrapper('path')(log)
log('file')

Corresponding decorator :

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def wrapper(path_name):
    def decorator(func):
        def inner(file_name):
            print("start logging in " + path_name)
            func(file_name)
            print("end")
        return inner
    return decorator


@wrapper('path')
def log(file_name):
    print("logging " + file_name)


log('file')

output:
start logging in path
logging file
end