non standard evaluation issue of qplot

[randy3k]

ggplot2's qplot uses rlang::enquos to capture the input expression. But we are passing the value instead of a promise so gplot fails to get the expression.

julia> qplot(1:10, 1:10)
ERROR: REvalError: Error: `expr` must quote a symbol, scalar, or call

[VPetukhov]

Have the same issue.

[randy3k]

Ya, it is also related to #42

Implicitly, qplot roughly equals to rcall(:qplot, 1:10, 1:10). And qplot expects an expression input rather a numeric input.