如何从Meteor包导出到我的应用程序命名空间？

Question

I know how to write Meteor packages but I can't seem to figure out how to have all exports land in my app's namespace, as described in this presentation .

This particular package is specific to an app I'm building, and it exports only one method that can be regarded as a decorator on the app's singleton. I tried api.export('MyApp.myMethod') but that gives an error native: Bad exported symbol: MyApp.myMethod .

If I just api.export('myMethod') , then in the app code I have to call myMethod() , and that's not namespaced.

Does Meteor have a mechanism similar to Node's var http = require('http'); ? Or how can packages export symbols into a given namespace?

Answer 1

The api.export method is only supported for top-level variables right now . It doesn't work for nested variables, because " it turned out that using deep exports was very confusing ", and what would you expect MyApp.myMethod to appear as in the global namespace if you also exported MyApp.myOtherMethod ?

You should just export MyPackage , and then call MyPackage.myMethod() . A common approach is to do something like

MyPackage = { 
    myMethod: someSecretMethodName,
    myOtherMethod: otherMethodName
}

And then call api.export("MyPackage") . This means that the exported names of variables don't necessarily have to be what you called them. This is used a lot in the core meteor packages; you can also see an example at for MongoInternals in mongo_driver.js .

Answer 2

All properties that you register in your app namespace are made available for the packages that depend on (use) your app-package. So, when you want to register a package namespace in an app-namespace, you declare the dependency on the app-package within your package and you register all of the methods/objects you want to export in the app-namespace. An example:

file: packages/myapp/namespace.js

MyApp = {};

file: packages/myapp/package.js

Package.on_use(function (api, where) {
  api.add_files([
    "namespace.js"
  ], ['client', 'server']);
  api.export("MyApp", ['client', 'server']);
});

file: packages/myapp-module1/logic.js

packageSpecificMethod = function(){}
moduleOne = {};
//you can export an module-specific namespace by registering it in the app-namespace
MyApp.module1 = moduleOne;
//or you can (if you dont want package-namespaces) register you private methods in the app-namespace directly
MyApp.exportedMethod = packageSpecificMethod;

file: packages/myapp-module1/package.js

Package.on_use(function (api, where) {
  api.use([
    'myapp'
  ], ['client', 'server']);
  api.add_files([
    "logic.js"
  ], ['client', 'server']);
});

Answer 3

In your package, you should define all methods and symbols in the namespace you want them to have, and then export that namespace. So, if in your package you've got:

MyApp = {
   myMethod: ...
};

Then you export it with api.export('MyApp') .

Unfortunately, there's no method similar to the one in Node you've mentioned, as all packages are loaded globally on startup.