Hi,
There's a feature in C# that allows one to create a verbatim string in which
escape characters have no effect, and strings can span multiple lines.  The
reason I want this is because regular expressions that have backslashes in
them must be converted so they use a double backslash instead.  This also
means that regular expressions can be copied directly out of a D file
without modification.  This isn't a big deal for regexps that have two or
three backslash characters, but the kind of regular expressions I often work
with are 100 characters or more (22 backslash chars in one I just looked
at).  The spanning multiple lines I don't use, and may not be a good idea,
but IMO, verbatim strings were an awesome idea for C# and I'd like to see
them in D as well.

here's some examples straight from the C# specification:
---------------------
string a = "hello, world";                  // hello, world
string b = @"hello, world";               // hello, world
string c = "hello \t world";               // hello     world
string d = @"hello \t world";               // hello \t world
string e = "Joe said \"Hello\" to me";      // Joe said "Hello" to me
string f = @"Joe said ""Hello"" to me";   // Joe said "Hello" to me
string g = "\\\\server\\share\\file.txt";   // \\server\share\file.txt
string h = @"\\server\share\file.txt";      // \\server\share\file.txt
string i = "one\ntwo\nthree";
string j = @"one
two
three";
---------------------

Can anyone think of any disadvantages to verbatim strings?  The '@' char is also wide and unmistakable; not to mention it isn't being used (afaik) for anything else in D. Also, what are your thoughts on the line spanning? Personally, I think it could get confusing.

This seems like it would be a fairly simple thing to impliment in the compiler, although I am not familiar with the structure of the compiler so I could be wrong.

Chris

Chris Lajoie wrote:

> Hi,
> There's a feature in C# that allows one to create a verbatim string in which
> escape characters have no effect, and strings can span multiple lines.  The
> reason I want this is because regular expressions that have backslashes in
> them must be converted so they use a double backslash instead.  This also
> means that regular expressions can be copied directly out of a D file
> without modification.  This isn't a big deal for regexps that have two or
> three backslash characters, but the kind of regular expressions I often work
> with are 100 characters or more (22 backslash chars in one I just looked
> at).  The spanning multiple lines I don't use, and may not be a good idea,
> but IMO, verbatim strings were an awesome idea for C# and I'd like to see
> them in D as well.

There are two ways to do this in D.  One is r"This string is verbatim", the other is using backquotes: `Look at me!`

All D string literals can span lines, I believe.

 -- andy

> verbatim strings were an awesome idea for C# and I'd like to see
>them in D as well.

This is obviously not C#'s original idea. Personally I think that using the '@' character is a bad idea and I prefer D's 'r'.

For your information, here's how Perl does it:
q/String that
spans multiple
lines and may contain embedded \ characters/

Note that you may choose one from many available delimiter characters: ', ", /, !, *, #, |, etc. or a pair of parentheses or brackets.

If that's still not enough, you can use the so-called "here document":
<<EOF
blah blah blah
all characters are available: ' " / { }
EOF
(use any text for EOF).

>Can anyone think of any disadvantages to verbatim strings?

In C#, you still have to escape the double-quote character or you can't use it inside verbatim strings at all (I don't remember).

> The '@' char is also wide and unmistakable; not to mention it isn't being used (afaik) for anything else in D.

This is a drawback. In the future it could be used for something more useful than verbatim strings.

> Also, what are your thoughts on the line spanning?
>Personally, I think it could get confusing.

It is sometimes useful, but rarely.

Well, D's r"" and `` are enough for me.

Piotr Fusik wrote:
> It is sometimes useful, but rarely.

The one place I find myself using them very often is in printing usage/help messages.  Ie:

void usage() {
    printf(r"Usage: program [options]
	-1	Option 1
	-2	Option 2
	-N	Option N
    ");
}

-C. Sauls
-Invironz

> > Hi,
> > There's a feature in C# that allows one to create a verbatim string in
which
> > escape characters have no effect, and strings can span multiple lines.
The
> > reason I want this is because regular expressions that have backslashes
in
> > them must be converted so they use a double backslash instead.  This
also
> > means that regular expressions can be copied directly out of a D file without modification.  This isn't a big deal for regexps that have two
or
> > three backslash characters, but the kind of regular expressions I often
work
> > with are 100 characters or more (22 backslash chars in one I just looked at).  The spanning multiple lines I don't use, and may not be a good
idea,
> > but IMO, verbatim strings were an awesome idea for C# and I'd like to
see
> > them in D as well.
>
> There are two ways to do this in D.  One is r"This string is verbatim", the other is using backquotes: `Look at me!`
>
> All D string literals can span lines, I believe.

After having read the documentation I never found anything regarding verbatim strings.  Can you point me to where they are discussed?  It's certainly possible I missed something, I skimmed most of it.  Thanks!

Chris

Chris Lajoie wrote:
>>There are two ways to do this in D.  One is r"This string is verbatim",
>>the other is using backquotes: `Look at me!`
>>
>>All D string literals can span lines, I believe.
> 
> 
> After having read the documentation I never found anything regarding
> verbatim strings.  Can you point me to where they are discussed?  It's
> certainly possible I missed something, I skimmed most of it.  Thanks!

It's in the "Lexical" section.  Scroll to "String Literals"

-- andy