使用 Appengine 和 Go 时的子文件夹和包

Question

When deploying and/or testing a Go project for appengine, the appcfg.py and dev_appserver.py tools are used to compile the project

That works fine when all the *.go files are in one folder, but how can a project be be compiled when code is divided into subfolders- yet also need to access functions and constants from eachother?

In Go- subfolders are by definition package boundaries, and I can't see a way to allow the appengine tools to compile multiple packages before testing or deploying, from one project.

Advice on how to tackle this- other than keeping it all in one folder, is appreciated. Even if the solution is to approach it one package (folder) at a time, advice on how to structure that for quick iteration on one project that uses all those packages is appreciated. Thanks!

Answer 1

There is no magic here. Just make sure each of your go files is placed in a folder and not in the root of your appengine project.

For example:

-[Project root]
    app.yaml
    -[packagea]
        packagea.go
        -[packageab]
            packageab.go
    -[packageb]
            packageb.go

In the example above, package declarations should be as follows:

• packagea.go:

   package packagea

• packageab.go

   package packageab

• packageb.go

   package packageb

And for example if packageb uses both packagea and packageab , import them as:

• packageb.go:

   import ( "packagea" "packagea/packageab" )

Note:

Note that you cannot create an import cycle (eg packagea imports packageb , and packageb imports packagea ):

Spec: Import declarations

An import declaration declares a dependency relation between the importing and imported package. It is illegal for a package to import itself, directly or indirectly.

You have to structure your code and packages to avoid import cycles or your code will not compile.