[swift-evolution] multi-line string literals.
cblessing at dvd.com
Mon May 2 13:29:27 CDT 2016
Forgive my naive interjection here. I’ve enjoyed lurking on this list and watching all the discussions around topics I don’t even fully understand, but this one strikes me.
I certainly agree that multi-line literals should be undistorted, and I also agree that they should be 100% easy to edit/read in the source. To that end, my (hold your breath) PHP dev days made great use of the heredoc syntax. I know it has been covered in this thread but I haven’t seen any compelling reason why it shouldn’t be the solution to this wanted feature.
var myString = <<<SOMETAG
// string content starts here after the new line
SOMETAG>>> // ends here
String interpolation could be implemented as-is:
var myString = <<<LETTER
I’m writing this letter to you… // more lines
// more lines
// more lines
There are a few constraints from PHP land which might make this easier (? simpler?) to implement:
- multi-line string contents begin on the NEXT line after the opening heredoc operator
- closing operator MUST have no prefix characters (so it must be directly after the last line of the string, and cannot be indented)
—> this means source code formatting can be a tad out of alignment with the rest of your code but then what multi-line string isn’t?
-> in fact the behavior is very similar to a <pre></pre> block of HTML, whitespace counts!
- absolutely no need for a line-by-line delimiter
- any character could be supported in the multi-line block
- string interpolation is completely possible (and could be made optional if that speeds things up)
- parser errors would be pretty simple to read and should be sufficient to prevent compile-time errors
Again apologies if this has already been shot down, and yes I fully admit that I don’t even know the origin of heredoc syntax (it’s probably something awful or great from the past) but objectively, I can’t see too many downsides to this solution.
> On May 2, 2016, at 7:47 AM, Rainer Brockerhoff via swift-evolution <swift-evolution at swift.org> wrote:
> On 5/2/16 09:53, Brent Royal-Gordon via swift-evolution wrote:
>> When you are embedding enormous string literals in source code, you
>> must put undistorted representation of the string above all other
>> considerations. If the design which best permits the string to be
>> written verbatim is ugly, bulky, unlike other language constructs,
>> disruptive to code readability, error-prone, arbitrary, difficult to
>> parse, or otherwise a wart on the language, that is simply the price we
>> have to pay for that feature.
> +1. I've tried to write this up a few times, but couldn't find a
> satisfactory syntax; still, how about introducing "named comments" or
> "footnotes in comments" like this:
> ...N lines of unescaped, as-is text
> and elsewhere in source referring to this with some #construct(label)
>> But it's a different story for short multiline strings. When you are
>> writing a little bit of text, but still more than one line, you don't
>> want to disrupt your code's indentation, add whole lines just for
>> delimiters, insert bizarre or cryptic tokens into your code, or create
>> syntax errors which take ten minutes to trace back to their source. You
>> want a different feature, with different tradeoffs.
> At least for Xcode having a "paste as escaped string" would solve this,
> other platforms/editors could have a standard macro with the same
> effect. Of course readability of the pasted literal would suffer.
> Rainer Brockerhoff <rainer at brockerhoff.net>
> Belo Horizonte, Brazil
> "In the affairs of others even fools are wise
> In their own business even sages err."
> swift-evolution mailing list
> swift-evolution at swift.org
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