== Why is this an issue?

Functions that use ``++yield++`` are known as "generators". Before Python 3.3, generators cannot ``++return++`` values. Similarly, functions that use ``++return++`` cannot use ``++yield++``. Doing so will cause a ``++SyntaxError++``.


Either upgrade your version of Python to a version >= 3.3, or don't use both return and yield in a function.


=== Noncompliant code example

[source,python]
----
def adder(n):
     num = 0
     while num < n:
         yield num
         num += 1
     return num  #Noncompliant
----


ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

Use only "return" or only "yield", not both.


'''
== Comments And Links
(visible only on this page)

=== on 17 Mar 2015, 08:41:25 Elena Vilchik wrote:
\[~ann.campbell.2] 

1. We should focus in rule description that "return" contains argument. "return" without argument can be used in generator. 

2. About labels: may be we should create tag for syntax error, and to use it in all such python rules. For example "syntax". What do you think?

=== on 17 Mar 2015, 17:48:41 Ann Campbell wrote:
\[~elena.vilchik] I've updated the description. See if it's enough.


I'm not wild about the proposed tag.

=== on 27 Nov 2019, 14:52:09 Nicolas Harraudeau wrote:
Deprecating this rule because it is possible to use ``++return++`` in a generator since Python 3.3, which was released on September 29, 2012.


The following code:

----
return 42
----
is equivalent to

----
raise StopIteration(42)
----

See https://www.python.org/dev/peps/pep-0380/#formal-semantics[PEP 380] for more information.


Note also that https://www.python.org/doc/sunset-python-2/[official python 2 support will be stopped on January 1, 2020], thus there is no point in having this rule enabled by default.

endif::env-github,rspecator-view[]