Hello,
You’ve hit a common challenge when embedding types in Go and wanting to maintain a fluent interface. While your code generation approach using reflect will certainly work, you’re right to pause and see if there’s a simpler, perhaps more idiomatic Go solution.
Unfortunately, without resorting to code generation, there isn’t a direct language feature in Go that automatically “lifts” and adapts the return types of embedded methods to the embedding type. The behavior you’re observing is by design: when you call Foo on a *MyType, the embedded ThirdPartyType’s Foo method is executed, and it naturally returns a *ThirdPartyType.
However, let’s explore a couple of alternative patterns that might reduce the boilerplate, though they might not be as perfectly seamless as your desired fluent chaining:
1. Providing Access to the Embedded Type:
Instead of trying to force the embedded methods to return *MyType, you could provide a way to access the underlying *ThirdPartyType if the user needs to continue chaining its methods:
type MyType struct {
*ThirdPartyType
}
func NewMyType() *MyType {
return &MyType{ThirdPartyType: NewThirdPartyType()}
}
func (mt *MyType) Bar(bar string) *MyType {
// ...
return mt
}
// Accessor for the underlying ThirdPartyType
func (mt *MyType) ThirdParty() *ThirdPartyType {
return mt.ThirdPartyType
}
// Usage:
mt := NewMyType().Bar("bar")
mt.ThirdParty().Foo("foo").// Continue chaining ThirdPartyType methods
// ...
This approach doesn’t give you the perfect NewMyType().Bar().Foo() syntax, but it avoids the need to re-implement all the methods. Users can still achieve the chaining if they explicitly access the embedded type.
Pros:
- No code generation needed.
- Relatively straightforward to implement.
- Avoids duplicating the logic of the
ThirdPartyType methods.
Cons:
- Doesn’t provide the exact fluent interface you initially wanted.
- Requires users to be aware of the embedded type and its accessor method.
2. Using Functional Options for Initialization:
While this doesn’t address the method chaining after initialization, it can help keep the initialization of MyType concise and potentially incorporate the configuration of the underlying ThirdPartyType:
type MyType struct {
*ThirdPartyType
// ... other fields
}
type MyTypeOption func(*MyType)
func NewMyType(options ...MyTypeOption) *MyType {
mt := &MyType{ThirdPartyType: NewThirdPartyType()}
for _, option := range options {
option(mt)
}
return mt
}
func WithFoo(foo string) MyTypeOption {
return func(mt *MyType) {
mt.Foo(foo) // Directly call the embedded method
}
}
func WithBar(bar string) MyTypeOption {
return func(mt *MyType) {
// Logic for setting Bar on MyType
// ...
}
}
// Usage:
mt := NewMyType(WithBar("bar"), WithFoo("foo"))
This pattern is more about the initial setup and less about subsequent method chaining of the embedded type. However, it’s a common and clean way to handle complex object initialization in Go.
Pros:
- Clean and readable initialization.
- Allows configuring both
MyType and the embedded ThirdPartyType during creation.
Cons:
- Doesn’t solve the method chaining issue after initialization.
Considering Your Situation:
Given that you have around 50 methods to potentially wrap, the manual re-implementation is indeed a significant amount of boilerplate and a maintenance burden.
While the “access the embedded type” approach is simpler, it compromises the fluent interface you desire.
Therefore, your idea of using code generation with reflect is likely the most pragmatic approach to achieve the exact fluent interface you’re aiming for without manually writing a large amount of repetitive code.
Before diving into full code generation, you might consider these aspects:
- Maintainability of the generated code: Ensure the generation process is robust and easy to rerun if the
ThirdPartyType changes.
- Readability of the generated code: While you won’t be writing it directly, consider how easy it will be to understand and debug if needed.
- Potential for a simpler generation strategy: Could you iterate through the methods of
ThirdPartyType using reflect and generate the wrapper methods dynamically within your application’s build process (though this might add complexity to your build)?
In conclusion, while Go doesn’t offer a built-in mechanism for automatically adapting embedded method return types for fluent interfaces, your code generation idea is a reasonable and likely the most effective solution for your specific needs, given the large number of methods involved. The alternative patterns offer trade-offs in terms of fluency or require explicit access to the embedded type.