On Thursday, 6 August 2020 at 00:58:39 UTC, Per Nordlöw wrote:
Is it possible to implement
template maxSizeOf(T...)
{
static if (T.length == 1)
enum size_t maxSizeOf = T[0].sizeof;
else
{
enum size_t firstSize = T[0].sizeof;
enum size_t maxSizeRest = maxSizeOf!(T[1 .. $]);
enum size_t maxSizeOf = firstSize >= maxSizeRest ?
firstSize : maxSizeRest;
}
}
in a non-recursive way?
Of course. In fact, it's trivial:
------
template maxSizeOf(T...)
{
align(1) union Impl {
T t;
}
enum maxSizeOf = Impl.sizeof;
}
------
To check that this does what we expect:
------
pragma(msg, maxSizeOf!(char)); // 1LU
pragma(msg, maxSizeOf!(char, short, ubyte)); // 2LU
pragma(msg, maxSizeOf!(char, long, ubyte)); // 8LU
align(1) struct S {
long l;
ubyte b;
}
pragma(msg, maxSizeOf!(long, S)); // 9LU
pragma(msg, maxSizeOf!(int, ubyte[7])); // 7LU
pragma(msg, maxSizeOf!(int, ubyte[3])); // 4LU
------
Why bother with recursion and all of that fancy gobbledygook when
the compiler already knows how to compute the maximum size of
something? ;-)
