best spec macro language reference ? help needed ...

[Jason Vas Dias]

Hi -

 Sorry my RPM skills are a bit rusty.

 I am trying to get a %{warn:...} message printed during spec file
 evaluation which prints different strings based on whether a
 variable has value 1 or value 0 (NOT whether it is non-%{nil}!) :

$ rpm --eval '%define aVar 1
%define isEN()  %["%1==1"]
%define EnStr() %{?%{isEN:%1}:%1 is Enabled}%{!?%{isEN:%1}:%1 is not Enabled}
%{warn: %{EnStr:aVar}}'
warning:  aVar}:aVar is not Enabled

 If someone could please point out where I am going wrong, or where
 I might find a more comprehensive / the best Spec File Macro Langurage
 Reference document, I'd be much obliged.

Thanks & Best Regards,
Jason