Comment #0 by qs.il.paperinik — 2024-04-09T10:27:27Z
On [Interpolation Expression Sequence](https://dlang.org/spec/istring.html) It says:
“A $ followed by any character other than a left parenthesis is treated as a literal $ in the expression, there is no need to escape it.”
That is a bad idea. Just make $ without a following parenthesis an error. A D programmer can easily escape it. Also, the fact that it has to be escaped makes sense.
There are two good reasons:
1. If the string literal is changed later so that the unescaped $ happens to be followed by an opening parenthesis, behavior changes.
2. It closes the door to introduce other uses for $ in IES literals forever (or: without breakage).
For example, variable shorthands: In a lot of scripting languages, "This is my $i-th attempt" puts the value of the variable `i` into the string. The same literal in D (prefixed with i as `i""`) is legal and changing its meaning further into the future is a bad idea. It rather have no meaning at all and be i"This is my \$i-th attempt", or i"This is my $(i)-th attempt", which is what the user probably wanted anyway.
Introducing variable shorthands later won’t make i"This is my $(i)-th attempt" invalid.
I’d also suggest to require $ to be escaped in interpolated token sequence strings. A backslash isn’t a valid token anyways, so in an `iq` string, \$ would be a special token that is translated to literal `$`, while unescaped $ would (for the time being) only be valid if a parenthesis follows.
About interpolated WYSIWYG strings, I’d go the same route as C# with `{{` meaning a single `{` in an `@` string: Even here, `$` should be escaped, however, because the main point of WYSIWYGs is that backslashes need no escaping, my suggestion would be to require that a `$` is followed by a parenthesis or another `$`, and double `$` means a single `$` in the string.
Comment #1 by robert.schadek — 2024-12-13T19:34:33Z