Wanted: Format character for source code literal

[H. S. Teoh]

On Fri, Apr 30, 2021 at 07:10:38AM +0000, Berni44 via Digitalmars-d wrote:
> I plan to add an extension to `std.format`, namely a new format
> character with the meaning of producing a source code literal. Or more
> formally, the following snippet should work for every type this
> extension will support:
> 
> ```
> enum a = <something>;
> enum b = mixin(format!"%S"(a));
> 
> static assert(a == b && is(typeof(a) == typeof(b)));
> ```
[...]

What's the scope of this feature? Can <something> be, say, a code
literal like a lambda? Can std.format even support printing the function
body of a lambda in a way that can be parsed by mixin()?  How far do we
intend to go with this?  Or does this only apply to POD values?

I can imagine there'd be problems if you have, say, a class from a
different module with private members, possibly with nested private
classes, so you couldn't actually reconstruct the class instance from a
string alone.

Unless the scope is significantly constrained, I see the potential for
this feature devolving into a big time-sink that really only caters to a
niche use-case. I'd be happy to be proven wrong, though.


T

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