On Thursday, 16 February 2017 at 00:40:19 UTC, John Colvin wrote:
On Wednesday, 15 February 2017 at 19:39:52 UTC, Andrei
Alexandrescu wrote:
On 02/15/2017 06:20 AM, Daniel N wrote:
On Wednesday, 15 February 2017 at 09:22:14 UTC, Daniel N
wrote:
template every(T...)
{
template satisfies(U...)
{
enum satisfies = true;
}
}
(lunch-break => time to hack D!)
template every(T...)
{
template satisfies(U...)
{
enum satisfies = {
foreach(t; T)
foreach(u; U)
if(!u!t)
return false;
return true;
}();
}
}
That looks pretty neat. Can you find 4-5 cases in which this
could be used gainfully in Phobos? Thanks! -- Andrei
Slightly OT, but it is related so bear with me:
Design by introspection is great and prevent having to make new
names for every possible combo of features. Unfortunately, it
doesn't work so well for introspecting multiple types at once:
normally you have to then make a new symbol, with a new name,
to pass to e.g. allSatisfy. That annoys me, so I've been
wanting this sort of thing for a while (which would also make
`every` way better to use, instead of having to make a name for
every predicate:
You know how we have named parameterised enums and aliases?
enum isInt(a) = is(a == int);
and
alias sizeof(a) = a.sizeof;
why not allow *anonymous* parameterised enums and aliases, like
this:
enum areAllInt(TL ...) = allSatisfy!(enum(a) => is(a == int),
TL);
void foo(TL...)(TL args)
if (allSatisfy!(enum(T) => T.sizeof <= 4, TL))
{
// ...
}
[snip]
I have a library that allows just that, but with even shorter
syntax :P
https://github.com/ZombineDev/rxd/blob/v0.0.3/source/rxd/xf/xform.d#L50
https://github.com/ZombineDev/rxd/blob/v0.0.3/source/rxd/meta2/type.d#L241
Though I have feeling that it will make uplinkCoder cringe,
because of the pressure it is probably putting on the compiler :D
