Metapost variable problem

[Michal Kvasnicka <quasar@econ.muni.cz>]

Good afternoon.

I am sorry that I bother you with this offtopic but I don't know where 
else I can ask.

I want to prepare a better interface for my metapost macros. I want to 
use the record-like variables to store "object" information. But I don't 
know how to copy such records. More precisely, let's suppose I have

    string a.type; a.type:="ecicsqrt";
    string a.name; a.name:="indifference curve number 1";
    string a.A; a.A:="1";
    string a.B; a.B:="1";
    ...

And I want to copy it to a record b. But
    b:=a;
doesn't work (now b is equal to some unknown token a).

Is there some simple way to do it, or have I to copy it manually like this:
    string b.type; b.type:=a.type;
    ...

Many thanks for your help. With wishes of nice summer
Michal Kvasnicka