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What is yield and return
To this day i still dont know what they mean but i see them a lot. Can i please have some help
3 ответов
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Yield and return are used in functions.
Return stops the function, and returns a value:
def func():
return 6
When you refer to it like x = func(), it will be 6.
It can also be used by itself to break the function:
def loop():
if (x == 3):
return
this will break the function if the x value equals 0.
Yield means the same as return, except it is used in recursive functions or infinite loops:
def inf():
print(7)
yield
This will cause an infinite loop
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return:
Is a keyword used to return a single object within function call. When return is used, function call is terminated.
yield:
Is a keyword used to return a generator object. A sequence of objects, similar to lists. The squence can be used in for loops or can be converted to lists to be used.
yield will not terminate the function call.
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Let's go simple.
Suppose you method is like doing a calculus. At the end of it, you obtain a result. The return keywords is used to communicate this result to the rest of the program.
Some methods don't need to return values, so the return statement is not required in a method.
The yield keyword is similar to the return, except that you're not declaring a function but a generator. The difference is that generator keep tracks of their previous calls unlike methods and so can change their behavior over time.
See it like this :
Suppose you want to represent a cookie jar.
Using method to take a cookie and a variable that exists outside the method and counts the amount of cookie remaining in the jar, you can tell if the person can or can't take a cookie (if the jar is empty)
Now, using the generator, the amount of cookie remaining can be stored within the generator, meaning that each time you call it, you get a cookie, but once it's empty you get nothing
Hope I'm clear. If I'm not, don't hesitate to ask