[swift-evolution] [Review] SE-0168: Multi-Line String Literals

[BJ Homer]

I’m not saying that the + operator should automatically add a newline. I’m saying that both strings should contain a trailing newline, such that the visible result is the same.

By contrast, this would feel really strange:

let a = """
This is line one
This is line two

"""

let b = """
This is line three
This is line four
"""

(a + b) == """
This is line one
This is line two
This is line three
This is line four
"""

On initial intuition, it seems strange that ‘a’ has a blatantly visible blank line at the end which seemingly “disappears” when the strings are concatenated. If I think about it for a bit, I can understand why that would be the case, but I think it’s non-obvious.

-BJ

> On Apr 14, 2017, at 3:49 PM, Xiaodi Wu <xiaodi.wu at gmail.com> wrote:
> 
> I disagree. I expect the last result to be from `a + "\n" + b`, for the reasons I outlined earlier.
> 
> The concatenation operator + does not introduce implied separators when joining strings. There is no reason to think that it should for multi-line strings specifically.
> On Fri, Apr 14, 2017 at 16:35 BJ Homer via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
> 
>> Consider these two examples:
>> 
>> let string_1 = """foo"""
>> 
>> 
>> let string_2 = """
>>     foo
>>     """
>> What’s the intuitive result you’d expect without taking all the long talk from the list into account?
>> 
>> Personally, I’d say string_1 == string_2 is true.
>> 
> 
> I think it’s reasonable to expect them to be different, actually. I might call these “single-line” and “multi-line” mode strings. The single-line mode is primarily useful for being able to include unescaped double-quotes in the string. If you’re in multi-line mode, though, it’s reasonable to be thinking about things in terms of “lines”, and having a trailing newline there seems reasonable. For example, I think it’s reasonable to expect this:
> 
> let a = """
> This is line one
> This is line two"
> """
> 
> let b = """
> This is line three
> This is line four
> """
> 
> (a + b) == """
> This is line one
> This is line two
> This is line three
> This is line four
> """
> 
> That seems like a reasonable model to work with multi-line strings.
> 
> -BJ
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