MetaPost - How do I turn off 'end occured when if...' messages?

Question

Consider the following code:

beginfig(1);

i:=0;

forever: 

    if odd i:
        show(i);
        exitif true;
    fi

    i:=i+1;
endfor

endfig;

end

When I run it, I get (end occurred when if on line 13 was incomplete).

Is there is a way to turn these messages off?

Answer 1

There might be a better way, but similarly to conditionals in TeX, one way is to ensure that fi is expanded before exitif is executed. So e.g.

beginfig(1);

i:=0;

forever: 

    if odd i:
        show(i);
        expandafter exitif expandafter true expandafter;
    fi

    i:=i+1;
endfor
endfig;

end

or

beginfig(1);

i:=0;

forever: 

    if odd i:
        show(i);
        scantokens "fi"
        exitif true;
    fi

    i:=i+1;
endfor
endfig;

end

In the second version, the scantokens hides the first fi when the condition is false, while it is executed when the condition is true and the second fi is skipped.