Verbatim String Literals

bgrommes

In situations involving, e.g., Windows path strings and, particularly, in regular expressions (which can at times be hard enough to read in their own right), the need to escape backslashes is reduces readability. Verbatim string literals would help with this:

Var rx As New Regex(@".\d{3}-\d{3}-\d{4}$")

In a verbatim string, only double quote marks still need escaping, via doubling. But I find this easier reading as well:

Var msg As String = @"The rain in Spain stays ""mainly"" upon the plain :-\"

That said, I'm not a fan of prepending variables with @ to allow the use of a variable named the same as a language keyword, which is the other way C# allows this syntax.

Garry

Thanks for this suggestion. I agree that doubled backslashes make paths and regular expressions needlessly difficult to read.

I’ve implemented verbatim string literals for the next release, with a slightly more Objo-like syntax than C#’s @"...":

Var rx As New RegEx(%"^\d{3}-\d{3}-\d{4}$")
Var path As String = %"C:\Users\Garry\Documents\"
Var message As String = %"The rain in Spain stays ""mainly"" upon the plain."

The rules are deliberately simple:

A verbatim string begins with %" and ends with ".
Backslashes are ordinary characters; escape sequences are not processed.
A double quote inside the string is written twice: "".
Braces are ordinary characters and interpolation is never performed.
Verbatim strings are single-line and produce normal String values.

For example:

Var text As String = %"{name}\n"

That contains the literal characters {name}\n; neither the braces nor \n receive any special treatment.

I chose % because @ is already associated with compiler directives in Objo, while $@ feels rather C#-specific. % is short, visually distinctive, and has a little more of a BASIC flavour. It also does not conflict with the remainder operator because Objo uses Mod.

Not permitting interpolation is intentional. It keeps verbatim strings predictable: everything between the delimiters is literal apart from doubled quotes. When dynamic content is required, an ordinary interpolated string or concatenation remains clearer.

Thanks again for proposing this, it's a small addition, but a particularly useful one for regular expressions and Windows paths.

bgrommes

Garry Thanks, Garry!