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- Subject: Re: Feature request: "u" option to file:read
- From: Roberto Ierusalimschy <roberto@...>
- Date: Fri, 23 Feb 2018 12:54:26 -0300
> If we have to be able to put the read pointer back where it was before
> the read in case the character is invalid (e.g. so a different
> function could read out the raw bytes) then that couldn't be done with
> a single unget.
The reading of numbers already poses a similar problem, and Lua solves
it the simple way. From the manual:
"n": reads a numeral and returns it as a float or an integer,
following the lexical conventions of Lua. (The numeral may have leading
spaces and a sign.) This format always reads the longest input sequence
that is a valid prefix for a numeral; if that prefix does not form a
valid numeral (e.g., an empty string, "0x", or "3.4e-"), it is discarded
and the function returns nil.