Intro
This is a illustrative example code, which tries to demonstrate
how generators and yield statements are related in python.
print("# `yield` a fancy way of pausing execution of a function.\n")
print("# Let's begin with a complex example\n")
def smart_yield():
for item in range(0, 4):
yield item
print("# We can only access value of a generator by itterating over it.")
print()
for item in smart_yield():
print(f'smart_yield item: {item}')
print()
def stupid_yield():
print("# Each iteration progresses the code by consuming one `yield` at a time")
print()
yield 0
yield 1
yield 2
yield 3
print("# No more yield keywords exist, let's close the generator")
print()
for item in stupid_yield():
print(f'stupid_yield item: {item}')
print()
def hybrid_yield():
print("# Generators remember last `yield` they returned")
print()
yield 0
yield 1
for item in range(2, 4):
yield item
print("# We have finished executing hybrid_yield")
print("# Notice that hybrid_yield ran 5 times (intermittently) instead of expected 4")
print()
for item in hybrid_yield():
print(f'hybrid_yield item: {item}')
conclusions ="""
# Conclusions:
- Yield allows us to pause code execution while being able to do something else
- Since we paused execution we can jump back into it at any time.
- each `yield <value>` is like a `return <value>`
- since we remember that last `yield` statement we don't execute it again
- Generator functions `run n+1` times where n - number of yield keywords in
a function.
- You should imagine yield keyword a way of slicing function to small pausable functions
"""
print(conclusions)
Source Output
If you are lazy and don’t want to run his code. Here is the output:
# `yield` a fancy way of pausing execution of a function.
# Let's begin with a complex example
# We can only access value of a generator by itterating over it.
smart_yield item: 0
smart_yield item: 1
smart_yield item: 2
smart_yield item: 3
# Each iteration progresses the code by consuming one `yield` at a time
stupid_yield item: 0
stupid_yield item: 1
stupid_yield item: 2
stupid_yield item: 3
# No more yield keywords exist, let's close the generator
# Generators remember last `yield` they returned
hybrid_yield item: 0
hybrid_yield item: 1
hybrid_yield item: 2
hybrid_yield item: 3
# We have finished executing hybrid_yield
# Notice that hybrid_yield ran 5 times (intermittently) instead of expected 4
# Conclusions:
- Yield allows us to pause code execution while being able to do something else
- Since we paused execution we can jump back into it at any time.
- each `yield <value>` is like a `return <value>`
- since we remember that last `yield` statement we don't execute it again
- Generator functions `run n+1` times where n - number of yield keywords in
a function.
- You should imagine yield keyword a way of slicing function to small pausable functions