The context to be used by the macro implementation.
The context to be used by the macro implementation.
Vanilla macro implementations have to carry it in their signatures, however when a macro is a full-fledged module, it can define the context next to the implementation, makes implementation signature more lightweight.
Returns string formatted according to given format string.
Returns string formatted according to given format string.
Format strings are as for String.format
(@see java.lang.String.format).
EXPERIMENTAL
Traditionally macro implementations are defined as methods, but this trait provides an alternative way of encoding macro impls as bundles, traits which extend
scala.reflect.macros.Macro.Instead of:
def impl[T: c.WeakTypeTag](c: Context)(x: c.Expr[Int]) = ...
One can write:
trait Impl extends Macro { def apply[T: c.WeakTypeTag](x: c.Expr[Int]) = ... }
Without changing anything else at all.
This language feature is useful in itself in cases when macro implementations are complex and need to be modularized. State of the art technique of addressing this need is quite heavyweight: http://docs.scala-lang.org/overviews/macros/overview.html#writing_bigger_macros.
However utility of this approach to writing macros isn't limited to just convenience. When a macro implementation becomes not just a function, but a full-fledged module, it can define callbacks that will be called by the compiler upon interesting events. In subsequent commits I will add support for programmable type inference