On Friday, 23 November 2018 at 10:34:11 UTC, John Chapman wrote:
I'm doing a fair amount of repeatedly checking if a function
compiles with __traits(compiles...), executing the function if
so, erroring out if not, like this:
static if (__traits(compiles, generateFunc1())) {
return generateFunc1();
} static if (__traits(compiles, generateFunc2())) {
return generateFunc2();
} else static assert(false);
But it seems inefficient to have to evaluate those functions
twice, so I'd like to optimise this so if __traits(compiles...)
succeeds, the result is cached and then used when the function
is actually called. I wondered if using std.functional.memoize
would help?
No, std.functional.memoize uses a hashtable to cache the runtime
results of calls to expensive functions.
assuming that the example is not oversimplified and generateFunc1
and generateFunc2 are functions, the compiler doesn't do extra
semantic analysis so the validity of the functions is effectively
cached.
If they are templates (with parameters) then the compiler will
automatically memoize them (it too keeps a hashtable of template
instances).
When in doubt, profile!
https://blog.thecybershadow.net/2018/02/07/dmdprof/
