Hello Team, I have a suspend function named 'build' that returns Either<Model, Error> and I'm ...

# android

[Pardeep Sharma]

Hello Team, I have a suspend function named 'build' that returns Either<Model, Error> and I'm this using member reference as:

val res = builder::build

where 'res' type = KSuspendFunction0<Either<Model, ApiError>>
However, I am expecting 'res' type should be: KSuspendFunction0*<Model?,* <Either<Model, Error>>>

whereas, in a normal scenario when I am calling:
val res = builder.build()
the 'res' type is as expected as Either<Model, Error>.

Am I missing something?

[ephemient]

builder::build is bound to builder

[Pardeep Sharma]

Sorry, I did not get many hints. Could you please elaborate?

[ephemient]

https://kotlinlang.org/docs/reflection.html#bound-function-and-property-references

[Pardeep Sharma]

I'd change the return type and calling way, It did not help much.

[ephemient]

if the function call is builder.build(), then builder::build also takes no arguments. it is bound to `builder`: the receiver is already pre-set to builder, as in { builder.build() }. why would you expect the type to contain an additional argument type?

[ephemient]

on the other hand (assuming the type is named Builder), Builder::build is not bound to an instance, so it does take an argument, similar to { builder -> builder.build() }. note the difference between a type and an instance on the left-hand side of ::

[Pardeep Sharma]

I am passing builder::build call to a generic method as a param, that accepts:

modelBuilder: suspend (model: T?) -> Either<T, Error>

[ephemient]

if the function is normally called by builder.build() then where do you expect the model parameter to go?

[Pardeep Sharma]

Got it, I was missing an optional nullable param. Thanks much.