Is it possible to know if a default argument was supplied as an actual parameter value (when they are equal) in Scala? -

is possible know if default argument supplied actual parameter value? in other words, assume defined method:

def mymethod(x: int = 1) = x + 1 

then possible distinguish between these 2 calls (which return identical results because parameter in second method call has same value default value in method definition) within method body:

mymethod() mymethod(1) 

in other words, want know if there technique achieve effect similar -supplied-p feature in common lisp function definitions (see http://www.gigamonkeys.com/book/functions.html , http://www.psg.com/~dlamkins/sl/chapter21.html details , more context).

no, can't directly know this.

here's ugly workaround relies on fact default parameter can method call. comes many caveats, biggest of is not thread-safe.

private var useddefault = false  private def default = {   useddefault = true   1 }  def mymethod(x: int = default) = {   if (useddefault) {     println("default")   } else {     println("supplied")   }   useddefault = false } 

another more practical workaround this:

def mymethod(): unit = mymethod(1, useddefault = true) def mymethod(x: int): unit = mymethod(x, useddefault = false)  private def mymethod(x: int, useddefault: boolean) = {   if (useddefault) {     println("default")   } else {     println("supplied")   } }