On 08/30/2013 01:57 PM, Joseph Rushton Wakeling wrote:
On 30/08/13 21:40, Benjamin Thaut wrote:
You need to put it into a static if, otherwise the compiler will continue
semantic checks on the second part of the expression. E.g.
template isGraph(G)
{
static if(__traits(hasMember, G, "directed"))
enum bool isGraph = isBoolean!(typeof(G.directed));
else
enum bool isGraph = false;
}
Ahh, right, thanks. :-)
Is there a recommended way for handling the case where there are many
such members -- say about 10 or more? The static if's could become very
highly nested with this approach. I suppose I could go through like this:
static if(!__traits(hasMember, G, "one"))
enum bool isGraph = false;
else static if(!__traits(hasMember, G, "two"))
enum bool isGraph = false;
else static if ...
...
else
{
// Now I know all the members exist and I can
// start checking out their properties ...
}
How about allSatisfy:
http://dlang.org/phobos/std_typetuple.html#.allSatisfy
Ali
