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Interpolation Expression Sequence (IES): Will Delimited Strings Ever Be Supported?
Aug 16, 2024
kdevel
Aug 16, 2024
Dejan Lekic
Aug 16, 2024
Dejan Lekic
Aug 16, 2024
kdevel
Aug 16, 2024
kdevel
Aug 16, 2024
kdevel
August 16, 2024
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void main ()
{
   auto html = iq"_
<!DOCTYPE html>
<html>
   <head>
      <title>$(title)</title>
      <link rel = "stylesheet" href = "style.css">
   </head>
   <body>
_";
}

$  dmd iesdl.d
iesdl.d(3): Error: semicolon expected following auto declaration, not `"_\n<!DOCTYPE html>\n<html>\n   <head>\n      <title>$(title)</title>\n      <link rel = "`
iesdl.d(8): Error: found `stylesheet` when expecting `;` following expression
iesdl.d(3):        expression: `"_\n<!DOCTYPE html>\n<html>\n   <head>\n      <title>$(title)</title>\n      <link rel = "`
iesdl.d(8): Error: found `style` when expecting `;` following expression
iesdl.d(8):        expression: `" href = "`
iesdl.d(8): Error: found `">\n   </head>\n   <body>\n_"` when expecting `;` following expression
August 16, 2024
Gravatar of Dejan LekicPosted by Dejan Lekic
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The answer is "yes, eventually". We were close with https://github.com/dlang/DIPs/blob/master/DIPs/rejected/DIP1027.md and Adam's one which I like even more - http://dpldocs.info/this-week-in-d/Blog.Posted_2019_05_13.html , but no consensus reached...

August 16, 2024
Gravatar of Dejan LekicPosted by Dejan Lekic
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After talking to Adam on IRC, he pointed out that i`` works, so I was wrong apparently. The following works:

   string title = "D roX";
   auto html = i`
<!DOCTYPE html>
<html>
   <head>
      <title>$(title)</title>
      <link rel = "stylesheet" href = "style.css">
   </head>
   <body>
`;

iq{} does not work because what is inside is not valid D code. i"" would work if you escaped all the double-quotes which obviously you do not want to do, so i`` to the rescue!

August 16, 2024
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On Friday, 16 August 2024 at 12:55:42 UTC, Dejan Lekic wrote:

>

After talking to Adam on IRC, he pointed out that i`` works, so I was wrong apparently. The following works:

   string title = "D roX";
   auto html = i`
<!DOCTYPE html>
<html>
   <head>
      <title>$(title)</title>
      <link rel = "stylesheet" href = "style.css">
   </head>
   <body>
`;

There is a \n at the beginning of the string. That is the reason for
using a delimited string [1]

   auto html = q"DELIMTER
<!DOCTYPE html>
...
DELIMITER";

[1] https://dlang.org/spec/lex.html#delimited_strings "The newline following the opening identifier is not part of the string [...]"

August 16, 2024
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On Friday, 16 August 2024 at 12:55:42 UTC, Dejan Lekic wrote:

>

iq{} does not work because what is inside is not valid D code.

Valid D code is not required, valid D tokens suffice [2].

   auto html = iq{
<!DOCTYPE html>
<html>
   <head>
      <title>$(title)</title>
   </head>
   <body>
};

Works (accidentally).

[2] https://dlang.org/spec/lex.html#string_literals "Token strings open with the characters q{ and close with the token }. In between must be valid D tokens."

August 16, 2024
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On Friday, 16 August 2024 at 13:49:58 UTC, kdevel wrote:
> [2] https://dlang.org/spec/lex.html#string_literals "Token strings open with the characters q{ and close with the token }. In between must be valid D tokens."

Sorry for replying to myself. But what constantly bothers me is
imprecise language in the documentation. Let me quote from the page
above:

"Token strings open with the characters q{ and close with the token }. In between must be valid D tokens."

Now from the example on that same page:

```
// q{ __EOF__ }         // error
                        // __EOF__ is not a token, it's end of file
```

__EOF__, however, /is/ a token, as we may read in [1] or [2].

[1] Issue 3695 - __EOF__ token not documented
    https://issues.dlang.org/show_bug.cgi?id=3695
    »In "D 1.x -> D 2.x migration guide" and in "lex.html", the new
     token __EOF__ introduced in the D 2 is not documented.

     I think it should be explained in the "Special Tokens" section.«

[2] Special Tokens
    https://dlang.org/spec/lex.html#specialtokens
    »__EOF__	tells the scanner to ignore everything after this token«