Scala macros referring to a member type -

i have trait member type, , want have macro signature containing type:

trait foo {   class bar[a] { ... }    def baz[a](x: bar[a]): bar[a] = macro bazimpl[a]    def bazimpl[a: c.weaktypetag](c: blackbox.context)(x: c.expr[bar[a]]) = ... } 

this doesn't work, since bazimpl must belong either static (i.e. non-member) object or macro bundle. in neither case have foo: foo write foo.bar[a].

one workaround can think of use foo#bar[a] , add casts:

trait foo {   class bar[a] { ... }    def baz[a](x: bar[a]): bar[a] = foo.baz1(x).asinstanceof[bar[a]]    def bazimpl[a: c.weaktypetag](c: blackbox.context)(x: c.expr[bar[a]]) = ... }  object foo {   def baz1[a](x: foo#bar[a]): foo#bar[a] = macro bazimpl[a]    def bazimpl[a: c.weaktypetag](c: blackbox.context)(x: c.expr[foo#bar[a]]): c.expr[foo#bar[a]] = ...  } 

but i'd avoid (both because it's not type-safe , because real case more complicated). alternatives?

if you're using scala 2.11, write c.tree everywhere instead of c.expr. cut down boilerplate of specifying same types in macro impls in macro defs @ virtually 0 cost. potential downside of trees in comparison exprs reify, requires splicees exprs, since of metaprograms in scala written quasiquotes these days, chances won't matter you.