[SIM117] Merge with statements for context managers that have same scope #35
Description
Explanation
A little known feature of Python is that a with statement can contain multiple context managers. This allows the code only one with statement (and therefore only 1 level of indentation). This rule has a similar rational to SIM102.
This rule should be applied if and only if:
- context A only contains the code of Context B and no other code. That is all the code in the nested statement will run with context A and B.
Caveat when implementing: If the context names are really long, the with statement may be broken over a line break. A new feature in the Python 3.10 alpha will be to allow parentheses to be used to break the with statement over multiple lines.
Example
Consider the following context managers:
#bad
with A() as a:
with B() as b:
print('hello')can be transformed into the following:
# Good
with A() as a, B() as b:
print('hello')