How to understand this code? Can you explain the logic of this code step by step? What is the logic of "a" argument in this "return lambda a : a * n" line of code?
def myfunc(n):
return lambda a : a * n
mydoubler = myfunc(2)
print(mydoubler(11))
myfunc returns a (lambda) function, this is just an unnamed function. The nameless function accepts one parameter, called a (yes, the function has no name, but its parameter is named). This nameless function accepts a and multiplies it by n, then returns the result.
mydoubler is a named instance of the unnamed (lambda) function, with the value 2 plugged into the parameter a. Each time you call mydoubler it uses the bound value for a, which is 2, and multiplies it by n as before, where n is the value 11.
First thing first, lambdas are anonymous functions. The form of a lambda can be generalized to the following form:
lambda arguments: expression
So, I think rewriting the lambda in myfunc() will help you understand what's going on. If the lambda were to be rewritten as a function:
def myfunc(n):
def lambda_as_func(a):
return a * n
return lambda_as_func
This snippet and your snippet, in essence, perform the same tasks: when myfunc() is called, a function is returned. The returned function takes one argument (a), which can be called later.
If you were to try it out:
>>> def myfunc(n):
def lambda_as_func(a):
return a * n
return lambda_as_func
>>> double = myfunc(2)
>>> double(11)
22
>>> double(50)
100
However, instead of defining another function within myfunc(), Python allows us to create lambda_as_func() as a one line function in the form as a lambda.
