Coerce a value in SASS

Question

I am trying to do the following statement in SASS:

($value * $ratio) + "em";

I am trying to get it to compile to a result like 16em but instead am getting "16em"

There appears to be a coercion function coerce(num_units, den_units), but I don't understand the documentation, it does not provide any examples, and when I try and compile it, it just spits the function out as a string.

Can anybody tell me how to get this function to work?

Answer 1

You've provided a link to the documentation for SASS source code, which is in Ruby.

The coerce function is an internal function and in fact is supposed to be applied as a method to a number, e. g. some_number.coerce(...).

This function is not available as SASS.

For the list of functions available in SASS, see this page: http://sass-lang.com/docs/yardoc/Sass/Script/Functions.html

There are no existing SASS functions to manipulate units, so you have to create your own:

@function strip-units($value)
  @if unitless($value)
    @return $value
  @else
    @return $value / ($value * 0 + 1)


@function add-unit($value, $new-unit)
  @return $value + 0#{$new-unit}


@function change-units($value, $new-unit)
  @return add-unit(strip-units($value), $new-unit)


$pxs-in-em: 16
@function pxtoem($px-value)
  @return change-units($px-value / $pxs-in-em, em)
@function emtopx($em-value)
  @return change-units($em-value * $pxs-in-em, px)




// Removing "px" from 1px
@warn "strip-units(1px)", strip-units(1px) // => 1

// Adding "px" to 1
@warn "add-unit(1, px)", add-unit(1, px) // => 1px

// Changing 1px to 1em
@warn "change-units(1px, em)", change-units(1px, em) // => 1em

// Converting 16px to 1em
@warn "pxtoem(16px)", pxtoem(16px) // => 1em

// Converting 1em to 16px
@warn "emtopx(1em)", emtopx(1em) // => 16px

Demo: http://sassbin.com/gist/5791446/