[Python-Dev] Subtle difference between f-strings and str.format() (original) (raw)

Chris Angelico rosuav at gmail.com
Thu Mar 29 10:08:42 EDT 2018


On Thu, Mar 29, 2018 at 11:28 PM, Steven D'Aprano <steve at pearwood.info> wrote:

On Wed, Mar 28, 2018 at 06:27:19PM +0300, Serhiy Storchaka wrote:

The optimizer already changes semantic. Non-optimized "if a and True:" would call bool(a) twice, but optimized code calls it only once. I don't understand this. Why would bool(a) be called twice, and when did this change? Surely calling it twice would be a bug. I just tried the oldest Python 3 I have on this computer, 3.2, and bool is only called once.

Technically not bool() itself, but the equivalent. Here's some similar code:



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