In order to improve modular namespacing, Sass 4 will only accept first-class functions as argument for call() so functions will be called in their own context. This allow developers to make their Sass packages more modular while still being able to call functions given by the user. As a first step, Sass 3.5 added get-function() to get a first-class function from its name and throw a warning if a function name string is passed to call().

We are now encouraged to use get-function(), but this would break our packages for older Sass versions. SassyFunctions is there to allow you to process first-hand functions and function name strings the same way and continue to support all Sass versions.

$ npm i -D sassy-functions

Then in Sass:

@import '/path/to/node_modules/sassy-functions/scss/sassy-functions';

Or with Eyeglass

@import 'sassy-functions';

Package maintainers, safely use any function reference or name coming from anywhere!

// Let's say you provide a "map-on-my-list" function to iterate with given function on a list...
@function map-on-my-list($list, $func) {
  $newlist: ();

  @each $v in $list {
    $newlist: append($newlist, sf-call($func, $v));
  }
  
  @return $newlist;
}

Package users, safely pass your own function names to anywhere!

// Let's say you have a "to-upper-case" function and want to map a list on it...
$my-list: ('hello', 'world');
$uppercased-list: map-on-my-list($my-list, sf-get-function(to-upper-case));

✨ There is more! See the API to discover all the functions of the SassyFunctions toolbox.

• sf-is-function($value)

  Return if a given value is a function name or reference.

  For example it returns true for:

  // A native Sass function name string
  $res: sf-is-function(rgba);
  // Your own function name string
  $res: sf-is-function('my-function');
  // An inexistant function name (any string can be a function name)
  $res: sf-is-function('xqxqqxhnxqh');
  // A first-class function (in Sass > 3.5)
  $res: sf-is-function(get-function(rgba));

  And it will returns false for:

  // Any value that is not a string or a first-class function
  $res: sf-is-function(0);
  $res: sf-is-function(());

  
  

• sf-is-callable($value)

  Return if a given value can be called.

  For example it returns true for:

  // A native Sass function name string
  $res: sf-is-function(rgba);
  // Your own function name string
  $res: sf-is-function('my-function');
  // A first-class function (in Sass > 3.5)
  $res: sf-is-function(get-function(rgba));

  And it will returns false for:

  // Any value that is not a string or a first-class function
  $res: sf-is-function(0);
  $res: sf-is-function(());
  // A function name that cannot be found
  $res: sf-is-function('xqxqqxhnxqh');

  
  

• sf-assert-function($value)

  Check if a given value is a function name or reference and throw an error otherwise. See sf-is-function for informations on the expected value.

  You can use it to check for your user arguments like:

  @function example($callback) {
    $_: sf-assert-function($callback);
  
    // ...your code with $callback secured..
  }

  
  

• sf-assert-callable($value)

  Check if a given value can be called and throw the appropriate error otherwise. See sf-is-callable for informations on the expected value.

  You can use it to check for your user arguments like:

  @function example($callback) {
    $_: sf-assert-callable($callback);
  
    // ...your code with $callback secured..
    $res: call($callback);
  }

  If $value is not a function, it will throw an error with the appropriate message according to the Sass version used, with migration guidelines if relevant.
  
  

• sf-get-function($func)

  Return a reference to the given function or a function name string so it is callable in the current Sass version. For Sass < 3.5, return the passed argument. For Sass >= 3.5, return a function reference if a function name string was passed.

  For example, use sf-get-function to get a function you can call no matter which Sass version is running.

  @function example($callback) {
    $safe-function: sf-get-function($callback);
  
    // ...your code with $safe-function secured..
  }

  
  

• sf-call($func, $args...)

  Polyfill for the call function supporting both function names and references. Calls the given function/name $func with all the following arguments $args...). If the function cannot be called, throw the appropriate error depending on the user environement.

  For example, use sf-call to call a user-provided callback no matter which Sass version is running.

  @function example($callback) {
    // ...do your stuff...
    $value: random();
  
    // ...then call the callback.
    $res: sf-call($callback, $value);
  }

  
  

  ---

  📖 See the full API documentation

  ---

You can install SassyFunctions locally and test it with:

# Clone the repo
git clone git@github.com:ncoden/sassy-functions.git
cd sassy-functions

# Install dependencies
npm install

# Run tests
npm test