[swift-evolution] multi-line string literals

Jason Dusek jason.dusek at gmail.com
Fri Dec 11 00:38:46 CST 2015

Yeah, I can't say I am totally committed to the fourth one.

On Thu, 10 Dec 2015 at 22:34 Travis Tilley <ttilley at gmail.com> wrote:

> I had been operating on the assumption that a leading blank line would be
> stripped if present, since the syntax in code would look much cleaner, but
> a trailing line would not since it would likely be intentional. I guess
> that's another detail that would need to be fleshed out if we decide to go
> with triple quote syntax (which, at this point, isn't a given... chris
> lattner brings up some very good points that might require more involved,
> potentially heredoc-like, syntax to solve).
> Your fourth rule, however, I don't agree with at all. It should be obvious
> from where you place the final quotes whether or not the string includes a
> trailing newline. Just like in ruby, I believe in and value the principle
> of least surprize.
> - Travis Tilley
> On Fri, Dec 11, 2015 at 1:04 AM, Jason Dusek <jason.dusek at gmail.com>
> wrote:
>> On Thu, 10 Dec 2015 at 21:45, Travis Tilley via swift-evolution <
>> swift-evolution at swift.org> wrote:
>> The ruby <<- heredoc syntax, unlike the << heredoc syntax, will strip
>>> indentation if necessary. Technically, it searches for the "least indented
>>> line" in the whole string, and removes exactly that amount from each line.
>>> So yes, the indentation problem -is- solved in ruby (though it might break
>>> entirely if you have empty lines, since the least indented line has no
>>> indentation).
>> To my mind, the rules should be:
>>    1. The indentation level is set from the least indented line that is
>>    not the first line and is not empty.
>>    2. A leading empty line is removed.
>>    3. The leading line, if there is any text in it, is not subject to
>>    de-indentation.
>> I genuinely believe these three rules taken together address all the
>> errors and infelicities to which triple quotes and HEREDOCs subject us.
>> Here are some examples:
>> text = """
>>     Some
>>   Features
>>     Are
>>     Discussed
>> """# From (1): The indentation is taken from the third line below `text`, so it's 2.# From (2): First line is: "\n" so it is removed.# From (3): No effect.
>> text = """  Some
>>           Features
>>             Are
>>             Discussed
>> """# From (1): The indentation is taken again from the line reading "Features". Here it is 10.# From (2): No effect.# From (3): The leading whitespace in `  Some` is preserved.
>> Do you all think these rules pass muster?
>> A fourth rule — one which seems advisable but also less necessary than
>> the others — is that a string constructed in this way always ends with a
>> newline. It is a rule that perhaps leads to surprises and inconsistencies.
>> Best Regards,
>> Jason
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.swift.org/pipermail/swift-evolution/attachments/20151211/81c784ae/attachment.html>

More information about the swift-evolution mailing list