Easy as df

as.df.R

dots <- function(...) {
    as.character(eval(substitute(alist(...))))
}
unL <- function(x) unlist(x, use.names = FALSE)

## easy as df
as.df <- function(x, ...) {
    vars <- dots(...)
    if (identical(vars, "FALSE")) {
        as.data.frame(x, stringsAsFactors = FALSE)
    } else if (identical(length(vars), 0L)) {
        if (is.matrix(x)) {
            x <- lapply(seq_len(ncol(x)), function(i) x[,i])
        }
        vars <- unL(lapply(x, function(x) class(x)[[1]]))
        vars <- abbreviate(vars, 3)
        vars <- mapply(paste0, vars,
                       rep(".", length(vars)),
                       seq_along(vars))
        structure(as.data.frame(
            x, stringsAsFactors = FALSE), names = vars)
    } else {
        if (any(grepl("^c\\(", vars),
                identical("varnames", vars))) vars <- unL(list(...))
        structure(as.data.frame(
            x, stringsAsFactors = FALSE), names = vars)
    }
}