Python-style decorator

Usage

decorate_function(orig, decor, ...)

lhs %D% rhs

Arguments

orig, lhs: any function
decor, rhs: decorator function that takes orig as its first argument
...: passed to decor

Examples



# Example 1: basic usage
# Decorator that prints summary of results and return results itself
verbose_summary <- function(...){
  summary_args <- list(...)
  function(f){
    function(...){
      results <- f(...)


      print(do.call(
        summary,
        c(list(results), summary_args)
      ))
      results

    }
  }

}

# runs as.list, but through verbose_summary
as_list2 <- decorate_function(as.list, verbose_summary)

# run test
res <- as_list2(1:3)  # will verbose summary
#>      Length Class  Mode   
#> [1,] 1      -none- numeric
#> [2,] 1      -none- numeric
#> [3,] 1      -none- numeric
identical(res, as.list(1:3))
#> [1] TRUE

# Example 2
x <- 1:20
y <- x + rnorm(20)

# decorator, add a line with slope 1 with given intercept
abline_xy <- function(b){
  function(f){
    function(...){
      f(...)
      intercept <- get_dots('intercept', 0, ...)
      abline(a = intercept, b = b)
    }
  }
}

# orig, plot whatever x vs jittered+intercept
plot_xy <- function(x, intercept = rnorm(1)){
  plot(x, jitter(x, amount = 3) + intercept)
}

# new function that decorate plot_xy with abline_xy, and
# returns the intercept
plot_xy2 <- decorate_function(plot_xy, abline_xy, b = 1)

# alternatively, you might also want to try
plot_xy2 <- plot_xy %D% abline_xy(b = 1)

plot_xy2(x = 1:20)