Do instrument creation functions in metric API need their own options?

[MrAlias]

Currently the options for instrument creation are defined as ...

1. Ones encompassing all instruments
   

   opentelemetry-go/metric/instrument/instrument.go

   Lines 32 to 38 in 9b398a6

   	// Option applies options to all instruments.
   	type Option interface {
   	Float64ObserverOption
   	Int64ObserverOption
   	Float64Option
   	Int64Option
   	}

2. Ones for float64 Observers
   

   opentelemetry-go/metric/instrument/asyncfloat64.go

   Lines 113 to 116 in 9b398a6

   	// Float64ObserverOption applies options to float64 Observer instruments.
   	type Float64ObserverOption interface {
   	applyFloat64Observer(Float64ObserverConfig) Float64ObserverConfig
   	}

3. Ones for int64 Observers
   

   opentelemetry-go/metric/instrument/asyncint64.go

   Lines 113 to 116 in 9b398a6

   	// Int64ObserverOption applies options to int64 Observer instruments.
   	type Int64ObserverOption interface {
   	applyInt64Observer(Int64ObserverConfig) Int64ObserverConfig
   	}

4. Ones for float64 synchronous instruments
   

   opentelemetry-go/metric/instrument/syncfloat64.go

   Lines 82 to 85 in 9b398a6

   	// Float64Option applies options to synchronous float64 instruments.
   	type Float64Option interface {
   	applyFloat64(Float64Config) Float64Config
   	}

5. Ones for in64 synchronous instruments
   

   opentelemetry-go/metric/instrument/syncint64.go

   Lines 82 to 85 in 9b398a6

   	// Int64Option applies options to synchronous int64 instruments.
   	type Int64Option interface {
   	applyInt64(Int64Config) Int64Config
   	}

There is no way to specify an option for a single instrument kind. There are changes to the OTel specification that are proposing such specificity may be needed: open-telemetry/opentelemetry-specification#3216

Proposal

Add options for each instrument.

This comes with the trade-off that the package API will have 12 additional option interfaces added to it and become cluttered.

Prior art

We decided to provide a span start and end options for similar reasons in the trace API.