Feature Requests: Support for Generics

[aimuz]

I'm trying to define structures using generalizations

Here is one of my structs

// ClusterStatus defines the observed state of Cluster.
type ClusterStatus struct {
	// ObservedGeneration is the 'Generation' of the Service that
	// was last processed by the controller.
	// +optional
	ObservedGeneration int64 `json:"observedGeneration,omitempty"`

	// Conditions is an array of current cluster conditions.
	// +optional
	Conditions []util.Condition[ClusterConditionType] `json:"conditions"`
}

type ClusterConditionType string


type GameStatus struct {
	// ObservedGeneration is the 'Generation' of the Service that
	// was last processed by the controller.
	// +optional
	ObservedGeneration int64 `json:"observedGeneration,omitempty"`

	// +optional
	Conditions []util.Condition[GameConditionType] `json:"conditions"`

}

type GameConditionType string

type Condition[ConditionType comparable] struct {
	// type of condition in CamelCase or in foo.example.com/CamelCase.
	// ---
	// Many .condition.type values are consistent across resources like Available, but because arbitrary conditions can be
	// useful (see .node.status.conditions), the ability to deconflict is important.
	// The regex it matches is (dns1123SubdomainFmt/)?(qualifiedNameFmt)
	// +required
	// +kubebuilder:validation:Required
	Type ConditionType `json:"type" protobuf:"bytes,1,opt,name=type"`
	// status of the condition, one of True, False, Unknown.
	// +required
	// +kubebuilder:validation:Required
	// +kubebuilder:validation:Enum=True;False;Unknown
	Status metav1.ConditionStatus `json:"status" protobuf:"bytes,2,opt,name=status"`
	// observedGeneration represents the .metadata.generation that the condition was set based upon.
	// For instance, if .metadata.generation is currently 12, but the .status.conditions[x].observedGeneration is 9, the condition is out of date
	// with respect to the current state of the instance.
	// +optional
	// +kubebuilder:validation:Minimum=0
	ObservedGeneration int64 `json:"observedGeneration,omitempty" protobuf:"varint,3,opt,name=observedGeneration"`
	// lastTransitionTime is the last time the condition transitioned from one status to another.
	// This should be when the underlying condition changed.  If that is not known, then using the time when the API field changed is acceptable.
	// +required
	// +kubebuilder:validation:Required
	// +kubebuilder:validation:Type=string
	// +kubebuilder:validation:Format=date-time
	LastTransitionTime metav1.Time `json:"lastTransitionTime" protobuf:"bytes,4,opt,name=lastTransitionTime"`
	// reason contains a programmatic identifier indicating the reason for the condition's last transition.
	// Producers of specific condition types may define expected values and meanings for this field,
	// and whether the values are considered a guaranteed API.
	// The value should be a CamelCase string.
	// This field may not be empty.
	// +required
	// +kubebuilder:validation:Required
	// +kubebuilder:validation:MaxLength=1024
	// +kubebuilder:validation:MinLength=1
	// +kubebuilder:validation:Pattern=`^[A-Za-z]([A-Za-z0-9_,:]*[A-Za-z0-9_])?$`
	Reason string `json:"reason" protobuf:"bytes,5,opt,name=reason"`
	// message is a human readable message indicating details about the transition.
	// This may be an empty string.
	// +required
	// +kubebuilder:validation:Required
	// +kubebuilder:validation:MaxLength=32768
	Message string `json:"message" protobuf:"bytes,6,opt,name=message"`
}

In this scenario, I can quickly reuse the Condition type because they have the same fields

When I generate this type using the current latest version (v0.13.0), I get the following error

/pkg/apis/util/condition.go:28:2: invalid field type: interface{comparable}
/pkg/apis/core/v1alpha1/cluster_types.go:54:15: unsupported AST kind *ast.IndexExpr
/pkg/apis/core/v1alpha1/game_types.go:92:2: unsupported AST kind *ast.IndexExpr

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/lifecycle stale

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues.

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• After 90d of inactivity, lifecycle/stale is applied
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/lifecycle rotten

[bennesp]

This would be really useful for my use cases too

[sbueringer]

Should we deduplicate the issues?

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues and PRs.

This bot triages issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

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/close not-planned

[k8s-ci-robot]

@k8s-triage-robot: Closing this issue, marking it as "Not Planned".

In response to this:

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues and PRs.

This bot triages issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Reopen this issue with /reopen
• Mark this issue as fresh with /remove-lifecycle rotten
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Please send feedback to sig-contributor-experience at kubernetes/community.

/close not-planned

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[mdbooth]

/reopen

Very interested in this. Is this on anybody's radar right now?

[k8s-ci-robot]

@mdbooth: Reopened this issue.

In response to this:

/reopen

Very interested in this. Is this on anybody's radar right now?

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[mdbooth]

/remove-lifecycle rotten

[k8s-triage-robot]

The Kubernetes project currently lacks enough contributors to adequately respond to all issues.

This bot triages un-triaged issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Mark this issue as fresh with /remove-lifecycle stale
• Close this issue with /close
• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/lifecycle stale

[sbueringer]

Very interested in this. Is this on anybody's radar right now?

This issue exists, apart from that, I don't know :) Not seeing much demand

[JoelSpeed]

Beyond applying an enum validation to the condition type here, what is the benefit of using generics here?

If you were to use metav1.Condition instead, what would you lose?

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues.

This bot triages un-triaged issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Mark this issue as fresh with /remove-lifecycle rotten
• Close this issue with /close
• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/lifecycle rotten