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digitalmars.D.learn - Expression templates in D1

I have been trying to create some simple expression templates in D1 but I've
run into trouble. Here is a reduced test case:

class A
    void opSub_r(T:int)(T a)
    void opSub(T)(T a)

void main(char[][] args)
    A a;
    a - 1;
    a - a; // line 20
    1 - a;

The error is:

test.d(20): Error: template test.A.opSub_r(T : int) does not match any function
template declaration
test.d(20): Error: template test.A.opSub_r(T : int) cannot deduce template
function from argument types !()(A)

My goal is to adjust the code such that the three expressions in the main
function all compile. Both opSub's must be templated functions (as far as I can
tell) so that the expression templates can work properly. Here is my full code,


Any ideas of any workabouts? Has anyone done expression templates in D1 and got
them to work?

And yes... the code above works fine in D2, but I want to try to get it to work
in D1 for now.


Apr 22 2011