On 15/08/2019 12:17:36, Petr Viktorin wrote:
On 8/15/19 10:40 AM, Greg Ewing wrote:
If we want a truly raw string format that allows all characters,
including any kind of quote, we could take a tip from Fortran:
s = 31HThis is a "totally raw" string!
Or from Rust:
let s = r"Here's a raw string";
let s = r#"Here's a raw string with "quotes" in it"#;
let s = r##"Here's r#"the raw string syntax"# in raw string"##;
let s = r###"and here's a '##"' as well"###;
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I rather like the idea! (Even though it would add to the proliferation
of string types.)
Obviously Python can't use # as the special character since that
introduces a comment,
and a lot of other possibilities are excluded because they would lead to
ambiguous syntax.
Say for the sake of argument we used "!" (exclamation mark). Possible
variations include:
(1) Like Rust:
s = r"Here's a raw string";
s = r!"Here's a raw string with "quotes" in it"!;
s = r!!"Here's r!"the raw string syntax"! in raw string"!!;
s = r!!!"and here's a '!!"' as well"!!!;
(2) Same, but omit the leading 'r' when using !:
s = r"Here's a raw string";
s = !"Here's a raw string with "quotes" in it"!;
s = !!"Here's a raw string with "quotes" and !exclamation marks! in
it"!!;
s = !!!"and here's a '!!"' as well"!!!;
# Cons: Would conflict with adding ! as an operator (or at minimum,
as a unary operator) for some other purpose in future.
# Makes it less obvious that a !string! is a raw string.
(3) Allow the user to specify his own delimiting character:
s = r!|This raw string can't contain a "bar".|
(4) As above, but the "!" is not required:
s = r|This raw string can't contain a "bar".|
# In this case the delimiter ought not to be a letter
# (it might conflict with current or future string prefixes);
# this could be forbidden.
(5) Similar, but allow the user to specify his own delimiting *string*
(specified between "!"s) (as long as it doesn't contain !):
let s = r!?@!Could this string could contain almost anything? Yes!?@
# The text in this string is:
# Could this string could contain almost
anything? Yes!
(6) Same except the first "!" is not required. In this case the first
character of the delimiting string should not be a letter:
let s = r?@!Could this string could contain almost anything? Yes!?@
# The text in this string is:
# Could this string could contain almost
anything? Yes!
I can dream ...
A point about the current syntax: It is not true that a raw string can't
end in a backslash,
as https://en.wikipedia.org/wiki/String_literal points out. It can't
end in an *odd number*
of backslashes. 42 is fine, 43 is no good. Which makes it seem even
more of a language wart
(think of program-generated art).
Rob Cliffe
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