DIP 1027--String Interpolation--Final Review Discussion Thread

[FeepingCreature]

Replying from review thread:

On Wednesday, 12 February 2020 at 11:49:11 UTC, Juraj Mojzis 
wrote:
> On Thursday, 30 January 2020 at 09:47:43 UTC, Mike Parker wrote:
>> This is the feedback thread for DIP 1027, "String 
>> Interpolation".
>
> If
> writefln(i"I ate $apples and ${%d}bananas totalling $(apples + 
> bananas) fruit.");
> gets rewritten as:
> writefln("I ate %s and %d totalling %s fruit.", apples, 
> bananas, apples + bananas);
>
> Than for function:
> void my_err_log(string err_msg, string file, int line, int 
> char) {...}
>
> called as:
> my_err_log(i"Error loading image $image_path.", src_file, 
> src_line, src_char);
>
> gets rewritten as:
> my_err_log("Error loading image %s message", image_path, 
> src_file, src_line, src_char);
>
> Results in an error but users will expect this to work.
>
> Worst case scenario is function that match:
> void draw_text(string text, int optional_x = 0, int optional_y 
> = 0) {...}
> callad as:
> draw_text(i"Today is $day.$month.");
>
>
> For example, Phobos exceptions are mostly defined as :
> this(string msg, string file = null, size_t line = 0)
> this(string msg, string file = __FILE__, size_t line = 
> __LINE__, Throwable next = null)
> etc.
>
> In my opinion, this is the fundamental flaw in the proposal.

Code that users expect to work resulting in an understandable 
error is the second-best outcome there is.

Since we don't have strong AI yet, given a situation that the 
compiler doesn't understand, this is pretty much the best result 
we can hope for. D has made a deliberate decision to eschew 
implicit conversions, so I don't think asking people to write

my_error_log(i"Error loading image $image_path".format, src_file, 
src_line, src_char);

instead is a big ask.

Re draw_text(), this is a valid problem and more ammunition for 
the 'i"" should return a templated struct' proposal, which would 
neatly eliminate this issue.