On Tuesday, 14 August 2018 at 09:17:41 UTC, ixid wrote:
On Tuesday, 14 August 2018 at 09:12:30 UTC, ixid wrote:
This will not compile as it says n is not known at compile
time...
This does work if 'value' is changed to immutable and fun to
accept it. So it still seems like a missed opportunity as enum
shouldn't be able to change either.
If 'value' is a global immutable, its value is known at
compile-time, and is equivalent to an enum except you can get its
address. If it's passed in a compile-time-compatible way
(generally, as a template parameter), it can thus be used as a
compile-time constant.
Now, as for your initial post: CTFE is run-time code, run at
compile-time. In other words, for a function to be CTFE-able, it
must be possible to run at run-time, and any compile-time
arguments must be passed in a compile-time-compatible way. Your
function 'fun' will not compile, because for it to run at
run-time, 'n' will need to be known.
H. S. Teoh has a great article on the wiki explaining the
different stages of compilation in D, which I think would be a
great help in your understanding of the differences:
https://wiki.dlang.org/User:Quickfur/Compile-time_vs._compile-time
--
Simen
