ALTER-CSS preprocessor


alter-css > sample.out.css


ALTER-CSS provides compact implementation of variables and blocks to separate static part of a css from the configuration part.


Variables are defined with $ followed by varname (alphanumeric) at column 1 (currently no indentation is allowed):

$var  value
Vars can be used (interpolated) anywere in the text:

background-color: $var
Single variable can hold multiple values:

$body_colors  #FFF  #000
which can be used this way:

  color:            $body_colors.1; 
  background-color: $body_colors.2; 
Thre is and $body_color.0 but it is the same as $body_color and represents the whole value (not splitted values, though splitted values are always available).


Vars and blocks names can include letters, numbers, dash and underscore. ALTER-CSS is case insensitive and does not make difference between dashes and underscores:

"var-NAME"   is the same as   "VAR_name"
Tech note (not visible to users): ALTER-CSS converts internally all names to uppercase with underscores.


All colors can have scale bumps. Scale bump is a number, which pushes all values up or down:

#158+3   will become   #48B
#FC2-4   will become   #B80
#FFF+2   will stay     #FFF
#002-5   will become   #000
Vars, which contain colors can also be bumped, but since minus sign is valid var name (dash), bumps must be separated with slash "/":

color: $action-color/+2
border: solid 1px $action-color/-2
Multiple var values can be used as usual:

color:            $action-color.1/+2
border: solid 1px $action-color.3/-2


Blocks are multi-line variables. They cannot be interpolated in the text but can be used separately on a single line and to instruct preprocessor to replace them with the multi-line value.

When defined, block names must not be indented (at column 1, same as vars) and they must be indented to be used:

/* must start at column 1 */
        color: $1;
        background-image: none;
        background-color: #2;
        border-top:    solid 1px $4;
        border-left:   solid 1px $4;
        border-bottom: solid 1px $5;
        border-right:  solid 1px $5;
and then be used as:

        cursor:  pointer;
        padding: 0.4em;
        $$color_box_3d   #FFF   #448   #559    #66A   #226
Blocks can have arguments, which are replaced upon use. Arguments are numbered, starting from 1, and are used with "$" inside block value:

$1 -- first arg
$2 -- second arg...
As vars, blocks also can access the whole argument list at any time with "$0" (even together with the separated arguments, $0, $1, $5, etc.)


CSS files can be included with $$$ and full name of the CSS file. "full name" means the required file name with or without path to access a file. This means file can have no path if it is in the current directory.



ALTER-CSS will skip and will not produce in output file all comment lines which start with:

Those are for commenting variables, blocks, includes, which will not be in the output file and will be confusing to leave comments for those empty spaces.

PLEASE NOTE: This will work only for single line comments: /*$ ... */


There are several predefined variables:

    this has value text of 
    this has the generation date and time
The puprose of $ALTER_CSS_GEN_WARNING and $ALTER_CSS_GEN_TIME to add aditional hints in the output file that this file is generated (i.e. modifications may not have an effect), and when it is generated.

Usual use will be:

so in the output file will be a comment saying do not modify the file and time of generation.


There is an example file called "", which has detailed explanation of using vars and blocks and small but complex enough example for mixing blocks and vars.

Example file can be processed this way:

alter-css > result.css

WHY $$$$s

The reason to choose $, $$, $$$ is that $var is a common script languages sigil and is well known. $$ means "multiple lines" and $$$ is "even more lines in a separate file" :) Initially @ and # are considered but they would clash with CSS syntax, and $ is (still) free.


Vladi Belperchinov-Shabanski "Cade" 
      <[email protected]> <[email protected]> <[email protected]>


ALTER-CSS is distributed under the GPL license, see COPYING file for the 
full text.

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