Compass: Is it possible to check if a compass compile is needed to be done?

If you're not using compass that much, why not search your code for the compass mixins you are using, and then cherry-picking those sass mixins from Compass's source code to reduce your compile time?

It was an interesting exercise for my own project--how much am I really using compass? Do I even need it? In my own project, we dropped support for IE9, so we didn't need compass to generate fallback SVG for background gradients for elements with rounded corners. And at that point, I asked myself, "Do I really need the full compass library to give me a mixin for corner radius?" The answer is no ...or maybe a partial yes--for those mixins I still really liked, I was able to browse their source code and grab just the functions and mixins I needed. If the mixins you're using aren't all that complicated, removing the dependency on compass completely will prove advantageous. The process to de-compassify your project with the aim to speed your compile time are these three steps.

1. Identify usages of compass in your source code.

I came up with comically large regex searches to find usages of compass-dependant syntax in my code. I used Sublime Text's flavor of regex, so these searches are unlikely to work in VS Code or other IDEs.

Regex to search for compass mixins that accept parameters:

\@include\s(adjust\-(font\-size\-to|leading\-to)|align\-(content|items|self)|alternating\-rows\-and\-columns|appearance|apply\-(origin|side\-rhythm\-border)|backface\-visibility|bang\-hack|baseline\-grid\-background|border\-bottom\-(left\-radius|radius|right\-radius)|border\-corner\-radius|border\-image|border\-left\-radius|border\-radius|border\-right\-radius|border\-top\-left\-radius|border\-top\-radius|border\-top\-right\-radius|box\-(align|direction|flex|flex\-group|lines|ordinal\-group|orient|pack|sizing)|break\-(after|before|inside)|color\-interpolation\-filters|column\-(break\-?(before|after|inside)|count|fill|gap|grid\-background|rule|rule\-(color|style|width)|span|span|width)|columns|content|contrasted|create\-transform|debug\-vertical\-alignment|delimited\-list|display\-flex|each\-gradient\-prefix|ellipsis|establish\-baseline|filter|filter\-gradient|filter\-margin|filter\-margin\-bottom|filter\-margin\-left|filter\-margin\-right|filter\-margin\-top|flex|flex\-(basis|direction|flow|grow|shrink|wrap)|flexbox|float|flow\-(from|into)|font\-face|for\-legacy\-browse(r|rs)|grid\-background|h\-borders|has\-layout|hide\-text|horizontal\-borders|horizontal\-list|horizontal\-list\-item|hyphens|image\-property|inline\-bloc(k|k\-)(list|list\-item)|inner\-table\-borders|justify\-content|keyframes|leader|leading\-border|link\-colors|list\-style|list\-style\-image|margin\-leader|margin\-trailer|min\-(height|width)|opacity|order|outer\-table\-borders|padding\-leader|padding\-trailer|perspective|perspective\-origin|prefix\-prop|prefixed\-properties|pretty\-bullets|print\-utilities|replace\-text|replace\-text\-with\-dimensions|reset\-(baseline|display|display|float)|rhythm|rhythm\-(borders|margins|padding)|rotate|rotate(3d|X|Y|Z)|scale|scale(3d|X|Y|Z)|selection|simple\-transform|single\-box\-shadow|single\-text\-shadow|single\-transition|skew|skew(X|Y)|sprite|sprite\-(background|background\-position|background\-rectangle|column|dimensions|img|position|replace\-text|replace\-text\-with\-dimensions|row)|sprites|sticky\-footer|stretch(|\-x|\-y)|tag\-cloud|trailer|transform|transform\-origin|transform\-style|transform2d|transform3d|translate(|3d|X|Y|Z|)|underscore\-hack|user\-select|with\-browser\-ranges|with\-each\-prefix|with\-prefix|word\-break)\(

Regex search for compass mixins without parameters

\@include\s(animation\-?(delay|direction|duration|fill\-mode|iteration\-count|name|play\-state|timing\-function)|background\-?(clip|image|origin|size|with\-css2\-fallback)|box\-shadow|clearfix|comma\-delimited\-list|display\-box|float\-left|float\-right|force\-wrap|global\-reset|has\-layout\-block|has\-layout\-zoom|horizontal\-list\-container|hover\-link|hyphenation|inline\-block\-list\-container|inline\-list|input\-placeholder|legacy\-pie\-clearfix|nested\-reset|nested\-reset|no\-bullet|no\-bullets|nowrap|opaque|pie\-clearfix|reset\-(body|box\-model|box\-model|focus|focus|font|font|html5|html5|image\-anchor\-border|image\-anchor\-border|list\-style|list\-style|quotation|quotation|table|table|table\-cell|table\-cell)|squish\-text|table\-scaffolding|text\-shadow|trailing\-border|transition|transition\-(delay|duration|property|timing\-function)|transparent|unstyled\-link|with\-browser\-support\-debugging)

Regex Search for Compass functions:

\s(brightness|browser\-out\-of\-scope|build\-grid\-background|comma\-list|contrast\-color|default\-box\-shadow|display\-browser\-range|get\-baseline\-gradient|get\-column\-fluid\-grid|get\-column\-gradient|has\-browser\-subset|intersect\-browser\-ranges|is\-time|linear\-gradient|lines\-for\-font\-size|prefix\-identifier|prefixed\-for\-transition|prefixes\-for\-capability|rhythm|set\-arglist\-default|support\-legacy\-browser|transition\-map|use\-prefix)\(

RegEx to Search for Compass VariablesLeaving these in your source code would be harmless as they don't rely on a call to compass.

\$(animation\-support\-threshold|background\-(clip\-support\-threshold|origin\-threshold|size\-threshold)|base\-(font\-size|half\-leader|leader|line\-height)|border\-image\-support\-threshold|border\-radius\-threshold|box\-shadow\-support\-threshold|box\-sizing\-support\-threshold|browser\-minimum\-versions|browsers\-supporting\-old\-webkit\-gradients|browsers\-supporting\-svg\-but\-not\-gradients|compass\-extensions|contrasted\-(dark\-default|light\-default)|critical\-usage\-threshold|css\-sel2\-support\-threshold|current\-browser\-versions|current\-prefix|debug\-browser\-support|default\-(animation\-(delay|direction|duration|fill\-mode|iteration\-count|name|play\-state|timing\-function)|background\-(clip|origin|size)|border\-radius|box\-(align|direction|flex|flex\-group|lines|ordinal\-group|orient|pack|shadow\-(blur|color|box|h\-offset|inset|spread|v\-offset)|\-sizing)|has\-layout\-approach|origin\-(x|y|z)|rhythm\-border\-(style|width)|rotate|scale\-(x|y|z)|skew\-(x|y)|text\-shadow\-(blur|color|h\-offset|shadspread|v\-offset)|transition\-(delay|duration|function|property)|translate\-(x|y|z)|vector\-(x|y|z))|disable\-magic\-sprite\-selectors|filter\-support\-threshold|flexbox\-support\-threshold|graceful\-usage\-threshold|gradient\-support\-threshold|grid-background\-(baseline\-(color|height)|column\-(color|width)|force\-fluid|gutter\-(color|width)|offset|total\-columns)|has\-layout\-support\-threshold|hide\-text\-direction|hyphens\-support\-threshold|ie6\-attribute\-hack\-support\-threshold|inline\-block\-alignment|inline\-block\-support\-threshold|input\-placeholder\-support\-threshold|legacy\-float\-support\-threshold|min\-line\-padding|multi|support\-threshold|opacity\-usage\-threshold|owg\-threshold|prefix\-context|regions\-support\-threshold|rem\-with\-px\-fallback|rhythm\-unit|round\-to\-nearest\-half\-line|selection\-support\-threshold|show\-baseline\-grid\-backgrounds|show\-|grid\-backgrounds|show\-grid\-backgrounds|sprite\-(default\-margin|default\-size|image\-default\-(height|width)|selectors)|supported\-browsers|svg\-gradient\-shim\-threshold|(transform|transition)\-support\-threshold|transitionable\-prefixed\-values|use\-legacy\-gradient\-syntax|use\-mozilla\-ellipsis\-binding|userselect\-support\-threshold)

2. Import only the portions of compass you need.

Once you have found where you're using compass, do a search through compass's source code for the the mixin and functions used in your code. Some functions require heavier lifting than others, for some of these mixins, you'll find you're better off keeping the whole compass eco-system in place (like for PNG generation, etc)

https://github.com/Compass/compass/tree/stable/core/stylesheets/compass

Copy those into a new sass file ( maybe call it _compass-lite.scss?). Their license allows this, just be sure to comment a nice reference in your sass file:

// Portions of this software Copyright (c) 2009-2014 Christopher M. Eppstein// Compass https://github.com/Compass/compass// @license https://github.com/Compass/compass/blob/stable/LICENSE.markdown

3. Profit.

If, on the other hand you only want to run compass when needed as stated in your question, or if the mixins you need are too complex, the above searches will help you in this goal. When you find a mixin that needs compass you can use use the @import "compass" flag before the initialization of only those particular files.

Update: A cleaner route (maintenance-wise not processing-speed-wise) is to use the compass-mixins (If you're using npm compass-mixins is a library of just the compass sass mixins, beware he's using a modified MIT license if that is a concern).For example:

  // Compass SCSS Mixins for:   // @mixin background // @mixin background // @mixin border-image // imports  "shared",  "../utilities/general/hacks",  "../functions"; @import '../../../node_modules/compass-mixins/lib/compass/css3/images'; (...Then your first usage of the mixin)

Notes on the compass-mixins approach:

• Your compiler will need to chew on more code than your are probably using, so if speed is the concern, cherry picking what you need is still the best way to go.

Notes on cherry picking your code:

• If you're using an autoprefixer, you can dispense with much of what the compass mixins are doing, many of the lines that add the -moz, -ms, -o prefixes can be removed; your autoprefixer will handle those for you.