aws
(aws-iotevents): golang: export _bind so that L2 constructs can be written in Go
Describe the feature
I want to write my own IAction in Go (for SNS publishing), but I cannot seem to satisfy the correct interface.
Looking at the definition:
export interface IAction {
/**
* Returns the AWS IoT Events action specification.
* @internal
*/
_bind(scope: Construct, options: ActionBindOptions): ActionConfig;
}
_bind is not exported so it is not part of the generated Go IAction.
the aws-iot Actions used to have Bind exported and I could write my own actions before CDK officially supported the DynamoDBv2 action.
Passing in a Go a struct with method:
func (action *IoTEventSNSAction) _Bind(scope constructs.Construct, options *iotevents.ActionBindOptions) *iotevents.ActionConfig {
results in panic: action._bind is not a function.
Alternatively, is there another way to achieve this?
Use Case
I have no way to extend the functionality here, except first write a Typescript class.
Proposed Solution
No response
Other Information
No response
Acknowledgements
- [ ] I may be able to implement this feature request
- [ ] This feature might incur a breaking change
CDK version used
2.73.0
Environment details (OS name and version, etc.)
macOS 13.3
I believe the Bind method is supposed to be internal and not to be exported.
What is your use case? Can you share more about your code?
@pahud I am trying to add the SNS Action (which is not currently implemented for the L2 construct) using my own Go code.
I also cannot downcast the L2 DetectorModel construct because
DetectorModel.(CfnDetectorModel).DetectorModelDefinition().(CfnDetectorModel.DetectorModelDefinitionProperty) does not work, seeing as the jsiiProxy object can't be type asserted to DetectorModelDefinitionProperty.
Any other ideas?
Issue Analysis
The Interface Implementation Problem
In TypeScript, this works:
// Interface definition
interface IAction {
_bind(): ActionConfig; // marked @internal
}
// Implementation (works even with @internal)
class MyAction implements IAction {
_bind() { return {...}; }
}
In Go, this fails:
// Generated Go interface (missing _bind due to @internal)
type IAction interface {
// _bind method is NOT generated
}
// Cannot implement - Go requires ALL interface methods
type MyAction struct{}
func (a *MyAction) _bind() ActionConfig { return ... } // Method doesn't exist in interface!
Purpose and Why
The need to create an SNS Action for IoT Events because:
- Missing Functionality: CDK doesn't provide an SNS action for IoT Events L2 constructs
- Extensibility: Rather than waiting for AWS to add it, they want to implement it themselves
- Go Preference: They're working in Go, not TypeScript
The Fundamental Issue
Without exporting _bind, Go developers have zero extensibility for IoT Events actions. They're completely locked out of creating custom actions, which defeats the purpose of having a public IAction interface.
The interface exists to enable extensibility, but the @internal annotation accidentally breaks that extensibility for non-TypeScript languages.