simple function to export a plot to EPS, with possible options

export_eps.R

## updated with input from @richfitz and @hadley - Thanks, guys!!
export_eps <- function(filename, expression, ...){
  old <- setEPS()
  on.exit(do.call(ps.options, old), add = TRUE)

  postscript(filename, ...)
  on.exit(dev.off(), add = TRUE)

  expression
}

Consider

export_eps <- function(filename, expression, ...){
  setEPS()
  postscript(filename, ...)
  on.exit(dev.off())
  eval(expression)
}

which will always close the device, even if expression fails.

Thanks @richfitz. I like this suggestion and have updated the gist.

FWIW eval() isn't necessary here. This would be sufficient:

export_eps <- function(filename, expression, ...){
  setEPS()
  postscript(filename, ...)
  on.exit(dev.off())
  expression
}

You should also consider resetting the ps options:

export_eps <- function(filename, expression, ...){
  old <- setEPS()
  on.exit(do.call(ps.options, old), add = TRUE)

  postscript(filename, ...)
  on.exit(dev.off(), add = TRUE)

  expression
}

@hadley I don't understand why I don't need to eval() the expression. I guess I need to go read that section in Advanced R (more closely).

Function arguments are lazily evaluated. So the plot expression won't actually be executed until it is called inside the function.