Continuation passing style vs. wrapper objects in dmd

[Andrei Alexandrescu]

On 5/25/21 1:56 PM, Dennis wrote:
> On Tuesday, 25 May 2021 at 17:21:16 UTC, Andrei Alexandrescu wrote:
>> int i = stat(stringz(name).ptr, &statbuf));
> 
> I much prefer that form too, but unfortunately it only works with 
> immediate use. This is a big pitfall:
> ```D
> {
> const(char)* s = stringz(name).ptr;
> // destructor runs here
> printf(s); // use after free
> }
> ```
> 
> You have to write:
> ```D
> {
> auto temp = stringz(name);
> const(char)* s = temp.ptr;
> printf(s); // good!
> // destructor runs here
> }
> 
> ```

The CPS is exposed to the problem as well:

const char* p;
module_name.toCStringThen!(name => p = name.ptr);

> The first form should be preventable with -dip1000, but it isn't currently:
> https://issues.dlang.org/show_bug.cgi?id=20880
> https://issues.dlang.org/show_bug.cgi?id=21868

DIP1000 should help both, but the wrapper object is (to me at least) 
vastly easier on the eyes. Not to mention composability (what if you 
have two of those...)