DIP 1027---String Interpolation---Community Review Round 1

[Patrick Schluter]

On Wednesday, 11 December 2019 at 11:35:05 UTC, rumbu wrote:
> On Wednesday, 11 December 2019 at 11:00:12 UTC, MrSmith wrote:
>> On Wednesday, 11 December 2019 at 10:48:56 UTC, Rumbu wrote:
>>> So we cannot have variables named d, s, f, g, x and so on 
>>> because they are standard format specifiers. What happens 
>>> with custom format specifiers, any one letter variable cannot 
>>> be interpolated?
>>
>> According to proposal you would wrap format specifiers into 
>> {}, like i"%{d}bananas"
>
> Nope, that means "use %d format specifier to print number of 
> bananas". According to the DIP, this is invalid:

No. Read the grammar. Format specifiers MUST be in {}.

Element:
     Character
     '%%'
     '%' Argument
     '%' FormatString Argument

FormatString:
     '{' FormatString '}'
     CharacterNoBraces

CharacterNoBraces:
     CharacterNoBrace
     CharacterNoBrace CharacterNoBraces

CharacterNoBrace:
     characters excluding '{' and '}'


characters does not exclude s, d, f, g etc.

>
> string what = "bread";
> int d = 10;
> writefln(i"making %what using %d ingredients");

which is transformed in

writefln("making %s using %s ingredients", what, d);