deepcopy-gen

Overview ¶

deepcopy-gen is a tool for auto-generating DeepCopy functions.

Given a list of input directories, it will generate DeepCopy and DeepCopyInto methods that efficiently perform a full deep-copy of each type. If these methods already exist (are predefined by the developer), they are used instead of generating new ones. Generated code will use standard value assignment whenever possible. If that is not possible it will try to call its own generated copy function for the type. Failing that, it will fall back on `conversion.Cloner.DeepCopy(val)` to make the copy. The resulting file will be stored in the same directory as the processed source package.

If interfaces are referenced in types, it is expected that corresponding DeepCopyInterfaceName methods exist, e.g. DeepCopyObject for runtime.Object. These can be predefined by the developer or generated through tags, see below. They must be added to the interfaces themselves manually, e.g.

type Object interface {
  ...
  DeepCopyObject() Object
}

Generation is governed by comment tags in the source. Any package may request DeepCopy generation by including a comment in the file-comments of one file, of the form:

// +k8s:deepcopy-gen=package

DeepCopy functions can be generated for individual types, rather than the entire package by specifying a comment on the type definition of the form:

// +k8s:deepcopy-gen=true

When generating for a whole package, individual types may opt out of DeepCopy generation by specifying a comment on the type definition of the form:

// +k8s:deepcopy-gen=false

Additional DeepCopyInterfaceName methods can be generated by specifying a comment on the type definition of the form:

// +k8s:deepcopy-gen:interfaces=k8s.io/kubernetes/runtime.Object,k8s.io/kubernetes/runtime.List

This leads to the generation of DeepCopyObject and DeepCopyList with the given interfaces as return types. We say that the tagged type implements deepcopy for the interfaces.

The deepcopy funcs for interfaces using "+k8s:deepcopy-gen:interfaces" use the pointer of the type as receiver. For those special cases where the non-pointer object should implement the interface, this can be done with:

// +k8s:deepcopy-gen:nonpointer-interfaces=true