[Python-Dev] Assignment expression and coding style: the while True case (original) (raw)

MRAB python at mrabarnett.plus.com
Wed Jul 4 19:49:52 EDT 2018

On 2018-07-04 23:51, Victor Stinner wrote: [snip]

(C)

while True: chunk = self.raw.read() if chunk in emptyvalues: nodataval = chunk break ... "nodataval = chunk" cannot be put into the "chunk := self.raw.read()" assignment expression combined with a test. At least, I don't see how. If that's the only 'break' in the loop, then you know that 'chunk' will have an 'empty' value after the loop, so you can change it to:

while True: chunk = self.raw.read() if chunk in empty_values: break ... nodata_val = chunk

which then leads to:

while (chunk := self.raw.read()) not in empty_values: ... nodata_val = chunk

[snip]

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