Question: simplify when all variables are real

Very often I have to insert map(assume,[k,lambda,L,...many others...],real) in order to simplify my expressions.

As a simple example, compare Re(exp(I*k*x)) assuming k::real,x::real; to the result without assuming.

So I'd like a procedure/command that makes Maple assume that every symbol in an expression is real but not the expression itself.

I found use RealDomain in (some expression) end; but this seems not to do what I want. I don't want, for example, to get "undefined" if sqrt(-3) is part of an expression but I only want that in some arbitrary expression like exp(I*x+theta) x and theta are seen as real just by using that command, without having to assume(x::real) and without setting something globally.

(I have Maple 10.04)