On 2018-04-01 05:36, Steven D'Aprano wrote:
On Sun, Apr 01, 2018 at 08:08:41AM -0400, Richard Damon wrote:
One comment about the 'combitorial explosion' is that it sort of assumes
that each individual combination case needs to be handled with distinct
code.
No -- as I said in an earlier post, Terry and I (and Eric) are talking
about the explosion in number of prefixes, not the complexity of the
code.
You are right that many of the prefixes can be handled by the same code:
rfd rfD rFd rFD rdf rdF rDf rDF
Rfd RfD RFd RFD Rdf RdF RDf RDF
frd frD fRd fRD fdr fdR fDr fDR
Frd FrD FRd FRD Fdr FdR FDr FDR
drf drF dRf dRF dfr dfR dFr dFR
Drf DrF DRf DRF Dfr DfR DFr DFR
# why did we support all these combinations? who uses them?
presumably will all handled by the same "raw dedent f-string" code. But
the parser still has to handle all those cases, and so does the person
reading the code.
And that *mental complexity* is (in my opinion) the biggest issue with
adding a new d-prefix, and why I would rather make it a method.
That doesn't seem a very reasonable argument to me. That is like
saying that a person reading code has to mentally slog through the
cognitive burden of understanding "all the combinations" of "a + b + c",
"a + b - c", "a * b + c", "a - b * c", etc. We don't. We know what the
operators mean and we build up our understanding of expressions by
combining them. Similarly, these string prefixes can mostly be thought
of as indepedent flags. You don't parse each combination separately;
you learn what each flag means and then build up your understanding of a
prefix by combining your understanding of the flags. (This is also
glossing over the fact that many of the combinations you list differ
only in case, which to my mind adds no extra cognitive load whatsoever.)
--
Brendan Barnwell
"Do not follow where the path may lead. Go, instead, where there is no
path, and leave a trail."
--author unknown
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