problem when using yield

[xsmyqf]

BPO	40354
Nosy	@mdickinson, @xsmyqf

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2020-04-22.00:14:52.329>
created_at = <Date 2020-04-21.17:05:16.196>
labels = ['type-bug', '3.7']
title = 'problem when using yield'
updated_at = <Date 2020-04-22.00:14:52.328>
user = 'https://github.com/xsmyqf'

bugs.python.org fields:

activity = <Date 2020-04-22.00:14:52.328>
actor = 'xsmyqf'
assignee = 'none'
closed = True
closed_date = <Date 2020-04-22.00:14:52.329>
closer = 'xsmyqf'
components = []
creation = <Date 2020-04-21.17:05:16.196>
creator = 'xsmyqf'
dependencies = []
files = []
hgrepos = []
issue_num = 40354
keywords = []
message_count = 3.0
messages = ['366931', '366933', '366961']
nosy_count = 2.0
nosy_names = ['mark.dickinson', 'xsmyqf']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue40354'
versions = ['Python 3.7']

[xsmyqf]

----------version1：--------------

def func1():
    a=0 
    b=10
    for i in range(4):
        result = yield a+100 if b>100 else (yield a)
        print(result)

f1 = func1()
print("value:%s" % next(f1))
print("--------------")
print("value:%s" % next(f1))
print("--------------")

----------version2--------------

def func1():
    a=0 
    b=10
    for i in range(4):
        result = (yield a+100) if b>100 else (yield a)
        print(result)

f1 = func1()
print("value:%s" % next(f1))
print("--------------")
print("value:%s" % next(f1))
print("--------------")

------------------problem------------------------
I think two version should behave same,but it did not.Do this will be treated as a bug ?

[mdickinson]

Which part of the behaviour do you think is a bug?

In version1, you want to think of the yield expression as though it were bracketed like this:

    result = yield (a+100 if b>100 else (yield a))

With the particular values of a and b that you have, that statement is equivalent to this:

    result = yield (yield 0)

This yields two values to the consumer: a 0 from the inner yield, followed by a None (or whatever was "sent" into the generator, if applicable) for the out yield.

In version 2, the corresponding line simplifies to just

    result = yield 0

So no, I don't think these two versions of the code should behave the same, and I don't think there's any bug here.

[xsmyqf]

Okay,I agree with you.I did not get the priority.