'use strict'; var Individual = require('./index.js'); module.exports = OneVersion; function OneVersion(moduleName, version, defaultValue) { var key = '__INDIVIDUAL_ONE_VERSION_' + moduleName; var enforceKey = key + '_ENFORCE_SINGLETON'; var versionValue = Individual(enforceKey, version); if (versionValue !== version) { throw new Error('Can only have one copy of ' + moduleName + '.\n' + 'You already have version ' + versionValue + ' installed.\n' + 'This means you cannot install version ' + version); } return Individual(key, defaultValue); }