Rest Params

Stylus supports rest parameters in the form of name.... These params consume the remaining arguments passed to a mixin or function. This is useful when utilizing (for example) the implicit function call support to apply vendor prefixes like -webkit or -moz.

In the example below, we consume all the arguments passed, and simply apply them to multiple properties.

box-shadow(args...)
  -webkit-box-shadow args
  -moz-box-shadow args
  box-shadow args

#login
  box-shadow 1px 2px 5px #eee

box-shadow(args...)
  -webkit-box-shadow args
  -moz-box-shadow args
  box-shadow args

#login
  box-shadow 1px 2px 5px #eee

Yielding:

#login {
  -webkit-box-shadow: 1px 2px 5px #eee;
  -moz-box-shadow: 1px 2px 5px #eee;
  box-shadow: 1px 2px 5px #eee;
}

#login {
  -webkit-box-shadow: 1px 2px 5px #eee;
  -moz-box-shadow: 1px 2px 5px #eee;
  box-shadow: 1px 2px 5px #eee;
}

If we wanted to peek at a specific argument—say, x-offset—we could simply use args[0]. Or, we may wish to redefine the mixin:

box-shadow(offset-x, args...)
  got-offset-x offset-x
  -webkit-box-shadow offset-x args
  -moz-box-shadow offset-x args
  box-shadow offset-x args

#login
  box-shadow 1px 2px 5px #eee

box-shadow(offset-x, args...)
  got-offset-x offset-x
  -webkit-box-shadow offset-x args
  -moz-box-shadow offset-x args
  box-shadow offset-x args

#login
  box-shadow 1px 2px 5px #eee

Yielding:

#login {
  got-offset-x: 1px;
  -webkit-box-shadow: 1px 2px 5px #eee;
  -moz-box-shadow: 1px 2px 5px #eee;
  box-shadow: 1px 2px 5px #eee;
}

#login {
  got-offset-x: 1px;
  -webkit-box-shadow: 1px 2px 5px #eee;
  -moz-box-shadow: 1px 2px 5px #eee;
  box-shadow: 1px 2px 5px #eee;
}

arguments

The arguments variable is injected into mixin and function bodies, containing the exact expression passed. This is useful for several reasons (especially vendor support) as you get the exact expression, commas and all.

For example, if we use a rest param, the comma is consumed (since it is an expression delimiter):

box-shadow(args...)
  -webkit-box-shadow args
  -moz-box-shadow args
  box-shadow args

#login
  box-shadow #ddd 1px 1px, #eee 2px 2px

box-shadow(args...)
  -webkit-box-shadow args
  -moz-box-shadow args
  box-shadow args

#login
  box-shadow #ddd 1px 1px, #eee 2px 2px

Yielding undesired results:

#login {
  -webkit-box-shadow: #ddd 1px 1px #eee 2px 2px;
  -moz-box-shadow: #ddd 1px 1px #eee 2px 2px;
  box-shadow: #ddd 1px 1px #eee 2px 2px;
}

#login {
  -webkit-box-shadow: #ddd 1px 1px #eee 2px 2px;
  -moz-box-shadow: #ddd 1px 1px #eee 2px 2px;
  box-shadow: #ddd 1px 1px #eee 2px 2px;
}

Let's redefine the mixin using arguments:

box-shadow()
  -webkit-box-shadow arguments
  -moz-box-shadow arguments
  box-shadow arguments

body
  box-shadow #ddd 1px 1px, #eee 2px 2px

box-shadow()
  -webkit-box-shadow arguments
  -moz-box-shadow arguments
  box-shadow arguments

body
  box-shadow #ddd 1px 1px, #eee 2px 2px

Now, yielding the desired result:

body {
  -webkit-box-shadow: #ddd 1px 1px, #eee 2px 2px;
  -moz-box-shadow: #ddd 1px 1px, #eee 2px 2px;
  box-shadow: #ddd 1px 1px, #eee 2px 2px;
}

body {
  -webkit-box-shadow: #ddd 1px 1px, #eee 2px 2px;
  -moz-box-shadow: #ddd 1px 1px, #eee 2px 2px;
  box-shadow: #ddd 1px 1px, #eee 2px 2px;
}

Rest Params #

arguments #

Rest Params

arguments