On Mon, Jun 29, 2020 at 05:29:31PM +0300, Mikhail V wrote:
> Proposal:
>
> Allow standard python escapes inside curly braces in f-strings.
> Main point is to make clear visual distinction between text and
> escaped chars:
There is already a clear visual distinction between text and escaped
chars: escaped chars begin with a backslash. Plain text does not.
So your proposal adds a second way to put escaped characters inside
f-strings, but not regular strings:
f"{x}\n" == f"{x}{\n}"
What you are adding is confusion between escaped chars and executable
expressions, since both will be surrounded by curly brackets:
# proposed syntax
f"text here {expression}"
f"text here {\n}"
Unlikely as it might be, there is still a chance that some day we
might add a backslash unary operator `\x`. This proposal would shut the
door to that possibility, since `f"{\n}"` would then be ambiguous.
For single-character escape codes, I see no benefit at all to this, only
disadvantages. However I do see a tiny potential benefit to hex escapes,
for the rare occassions that they are immediately followed by something
that looks like it could be part of the escape but isn't:
"\x2b2c" # Looks like '+,' but is '+2c'
Notice that this occurs for regular strings too, so a f-string only
proposal is not justified. Fix it for both or for neither, don't
introduce an inconsistency.
Counter-proposal: hex escapes allow optional curly brackets, similar to
unicode name escapes. You could even allow spaces within the braces, for
grouping:
# Existing:
"\N{HYPHEN-MINUS}" # '-'
"\x2b" # '+'
# Proposed enhancement:
"\x{2b}2c" # '+2c'
"\x{2b2c}" # '+,'
"\x{DEAD BEEF}" # "\xDE\xAD\xBE\xEF"
This could work in f-strings and bytes as well. I think this might be of
use for people who do a lot of work with binary file formats and hex
escapes.
I think this is backwards compatible too, since "\x{" is currently a
syntax error.
--
Steven
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