DIP 1027---String Interpolation---Format Assessment

[FeepingCreature]

On Monday, 24 February 2020 at 22:11:08 UTC, Walter Bright wrote:
> The semantics of an interpolated string must be defined by the 
> DIP, not deferred to some template. If the implementation of 
> those defined language features is done by a template, that is 
> an implementation choice, not part of the DIP or spec.
>

I don't understand this. The behavior of formatting strings is 
*currently* deferred to a template (std.format and co). This lets 
us do important decisions at compiletime, like writing the format 
string to a file or a string buffer piecewise without allocating 
memory. Why are you trying to get rid of this flexibility?

As I understand it, the point of a format string template is to 
keep exactly this kind of flexibility in exactly the same places 
it is currently available to users, while simultaneously 
improving syntax legibility. To emphasize this again: the @gc 
format string would have *reduced* flexibility for 90% of our 
usecases (templated nogc/lowgc log library calls). As proposed, I 
don't see why I would have ever used it.