[swift-evolution] multi-line string literals.

Ricardo Parada rparada at mac.com
Thu May 5 23:45:41 CDT 2016

If we use triple quotes (i.e. """) at the beginning of the multi line string literal and again at the end, it seems very unlikely that the heredoc notation would be needed. 

I would simplify and remove the heredoc alternative from the proposal. 

Also, for those of us who like the continuation quotes, I think the continuation quotes could be optional. For example this:

let html = """<html>
    ". <body>
    "     <h1>\(title)<h1>
    ".    <p class="fancy">A paragraph.<p>
    ". </body>

would be equivalent to:

let html = """<html>
    . <body>
    .    <p class="fancy">A paragraph.<p>
    . </body>

What do you think?

> On May 5, 2016, at 2:13 PM, L Mihalkovic via swift-evolution <swift-evolution at swift.org> wrote:
>> On May 5, 2016, at 12:30 PM, Michael Peternell via swift-evolution <swift-evolution at swift.org> wrote:
>> Hi,
>> it's not a secret that I'm not a big fan of the proposal. The third draft doesn't change this and it's unlikely that any future draft will, because for me, the problem are the continuation quotes, and for Brent it seems like they are a must-have-feature (correct me if I'm wrong.)
>> I just wanted to say that I have drafted a proposal that solves the issues that I have encountered. (It's here: https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160425/016219.html )
>> - it allows pasting text as-is
>> - it allows creating string literals where leading space on each line is stripped (while keeping indentation differences intact)
>> - it allows creating string literals where leading space on each line is not stripped
>> - optionally it allows strings to be raw, without any string interpolation or escaping whatsoever
>> - in none of the literals you have to write "<book id=\"bk101\" empty=\"\">", you can just write """<book id="bk101" empty="">""". This also lets you copy&paste text out of the program source and back into a HTML file.
>> It had the idea that maybe the motivation behind continuation quotes is to make using multiline strings harder to use; in order to discourage their use at all. Two points to consider:
>> - people who don't want to use MSL will not, even if you throw Python-like """multi-line strings""" at them.
>> - people who want to use them do it, even if there is no MSL available. I saw that in Objective-C, with multiple lines of HTML and CSS wrapped into a big multiline objc-string-literal and thrown at a WebView. I could send the literal to the console before sending it to the WebView and it was basically unreadable. I eventually refactored it to put the thing into a file (also because the HTML grew in space, and the inline-literal became impractical)
>> - my most important point: if someone uses multiple lines of HTML or CSS or XML directly within the code, I want it to look okay. I don't want an MSL feature that is so unwieldy that people voluntarily not use it; it would be better to have no MSL at all.
>> I don't think that multiline strings are a must-have feature for a language, because they are not used very often. (I included an example of a good use case in my proposal.) I acknowledge that in many programming cases it would be better to not put a huge pile of text directly into the source, but to load the text from a file at runtime. But even when these MSL are misused, I prefer to read a """python multiline string""" over a "concatenated\n"+"Java\n"+"String".
>> -Michael
> Hi Michael. hope this helps  https://gist.github.com/lmihalkovic/11f2b1b23b78bbb9cbf0292ffc480b3d
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