Weld

Weld is a golang package that contains directives for "state and backends" dependency injection using compile time code generation.

Weld is heavily based on github.com/google/wire, borrowing its syntax and concepts, but tailoring it for backends-based dependency injection pattern.

Unlike wire, weld:

• Supports multiple providers for the same type by selecting the first provider found in the set using depth-first search.
• Supports transitive "backends-type" cyclic dependencies by adding these interfaces to the generated implementation.
• Is much less dynamic & has fewer features: it takes a provider set as input and a backends as output and generates a Make function that returns an implementation of that backends interface.

For convenience it can also generate an aggregate Backends interface from the union of a slice of backends since golang doesn't support embedding interfaces with the same name or overlapping methods.

Relation to wire syntax:

• Supported functions and types:
  • wire.Bind
  • wire.Binding
  • wire.NewSet
  • wire.ProviderSet
• Unsupported functions and types:
  • wire.Build
  • wire.FieldsOf
  • wire.InterfaceValue
  • wire.Struct
  • wire.Value

Example

• See the internal/testdata/example project for how this is used.