[Python-Dev] PEP 572: Write vs Read, Understand and Control Flow

[Stephen J. Turnbull]

Chris Angelico writes:

 > Additionally, naming sub-parts of a large expression can assist an
 > interactive debugger, providing useful display hooks and partial
 > results. Without a way to capture sub-expressions inline, this
 > would require refactoring of the original code; with assignment
 > expressions, this merely requires the insertion of a few ``name
 > :=`` markers. Removing the need to refactor reduces the likelihood
 > that the code be inadvertently changed as part of debugging (a
 > common cause of Heisenbugs),

Period here preferred.

 > and is easier to dictate to a student or junior programmer.

True but gratuitous.  It's also true that it's easier to dictate to
Guido or Tim, though you might be happier if you let them refactor!