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Enum std.traits.member isIterable
Returns true if T can be iterated over using a foreach loop with
a single loop variable of automatically inferred type, regardless of how
the foreach loop is implemented. This includes ranges, structs/classes
that define opApply with a single loop variable, and builtin dynamic,
static and associative arrays.
Declaration
enum isIterable(T) = is(typeof(()
{
foreach (elem; T.init)
{
}
}
));
Example
struct OpApply
{
int opApply(int delegate(ref uint) dg) { assert(0); }
}
struct Range
{
@property uint front() { assert(0); }
void popFront() { assert(0); }
enum bool empty = false;
}
static assert( isIterable!(uint[]));
static assert( isIterable!OpApply);
static assert( isIterable!(uint[string]));
static assert( isIterable!Range);
static assert(!isIterable!uint);
Authors
Walter Bright,
Tomasz Stachowiak (isExpressions