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Go package: elist.
Dr. Alan U. Kennington.

The elist package implements the error-message-stack class Elist, which implements the standard Go interface error.

An Elist permits multiple errors messages to be pushed onto a single error-message-stack. Usage example:

    func function0() error {
        var E error = function1();
        if E != nil {
            return elist.Push(E, "function0: error returned by function1");
        }
        return nil;
    }

Any kind of error interface-implementation can be chained into an Elist.

The output from Elist::Error() has the error-traceback form suggested by this example.

    Error 1: "function0: error returned by function1".
    Error 2: "function1: error returned by function2".
    Error 3: "function2: [error description etc.]".

When the calling function function0() does not receive an error message from a called function function1(), a new Elist error-message-stack may be created as in the following example.

    func function0() error {
        var n int = function1();
        if n < 0 {
            return elist.Newf(
                "function0: negative value returned by function1: %d", n);
        }
        return nil;
    }

Then the caller of function0() may either print the error message which is returned, or else push a new message onto the returned message and pass that as a return value.