How can I define cas function of an operator(mathematical term)?

[Aleksandr94]

Than you for the reply!
I wanted to be able to choose integration variable explicitly.
So I tried
#CAS
MYINT(f,x):=
BEGIN
LOCAL fnz1;
vr1:=lname(f);
fnz1:=(vr1)->int(f,x);
RETURN fnz1(vr1);
END;
#end
Most likely HpPPPL mixes up "x" variables. So I need the way to tell him that "x" must be from MYINT(f,x).
These cas function didn't gave the correct result.