• =?UTF-8?B?Tm9yZGzDtnc=?= (8/8) Oct 17 2015 Does DMD cache template instantiations?
• Marc =?UTF-8?B?U2Now7x0eg==?= (9/17) Oct 17 2015 Yes, and it's required by the spec:

=?UTF-8?B?Tm9yZGzDtnc=?= <per.nordlow gmail.com> writes:

Does DMD cache template instantiations?

That is, is it preferred to do, for instance, either

     static      if (isIntegral!T && isUnsigned!(T)) {}
     else static if (isIntegral!T && isSigned!(T)) {}

or

     enum integral = isIntegral!T;
     static      if (integral && isUnsigned!(T)) {}
     else static if (integral && isSigned!(T)) {}

Marc =?UTF-8?B?U2Now7x0eg==?= <schuetzm gmx.net> writes:

On Saturday, 17 October 2015 at 07:48:39 UTC, Nordlöw wrote:
 Does DMD cache template instantiations?

Yes, and it's required by the spec:

"Multiple instantiations of a TemplateDeclaration with the same 
TemplateArgumentList all will refer to the same instantiation."
http://dlang.org/template.html

 That is, is it preferred to do, for instance, either

     static      if (isIntegral!T && isUnsigned!(T)) {}
     else static if (isIntegral!T && isSigned!(T)) {}

 or

     enum integral = isIntegral!T;
     static      if (integral && isUnsigned!(T)) {}
     else static if (integral && isSigned!(T)) {}

It *might* make a little difference if you have thousands of 
instantiations, because for each instantiation the compiler needs 
to check whether it has already instantiated the templation with 
that combination of arguments, but I wouldn't worry about it.