Look for the documentation in the source code lib/tech/v2.js or read an article on how to write your own techs (Russian only).
There are many ways to write a tech module.
Whatever manner you choose you can refer to the tech object from methods using this.
Any base method is available using this.__base(...) call. Tech class can be referenced
using this.__class. Thanks to inherit module
that helps us to organize inheritance here.
You only need to declare regular CommonJS module and export some of its
functions to redefine them. By default your tech will derive from base Tech class
defined in module lib/tech/v2.js.
exports.getCreateResult = function(...) {
// your code goes here
};You can also group all methods in techMixin object. This is a recommended way.
exports.techMixin = {
getCreateResult: function(...) {
// your code goes here
}
};Besides function, you can also export baseTechPath variable to define an
absolute path to a tech module you are extending. Or you can
var BEM = require('bem');
exports.baseTechPath = BEM.require.resolve('./techs/css');You can also derive from tech module by its name using baseTechName variable.
Base class will be chosen in the context of level where tech module will be used.
exports.baseTechName = 'css';In this example new tech will derive from css tech declared on level in file
.bem/level.js.
If you need a total control, you can create a module that exports
the whole Tech class.
var INHERIT = require('inherit'),
BaseTech = require('bem/lib/tech').Tech;
exports.Tech = INHERIT(BaseTech, {
create: function(prefix, vars, force) {
// do some creation work
},
build: function(prefixes, outputDir, outputName) {
// organize own build process
}
});If you need to base your tech on an existing one written in a simple way, use
getTechClass() function to get its class. We recommend to use getTechClass()
function all the time to not depend on tech implementation.
var INHERIT = require('inherit'),
BEM = require('bem'),
BaseTech = BEM.getTechClass(require.resolve('path/to/tech/module'));
exports.Tech = INHERIT(BaseTech, {
// your overrides go here
});