ServerOptions and ClientOptions use untyped dynamic options

client_options.go

@@ -15,37 +15,51 @@ package twirp
 import (
  "context"
  "net/http"
+ "reflect"
 )
 
 // ClientOption is a functional option for extending a Twirp client.
 type ClientOption func(*ClientOptions)
 
-// ClientOptions encapsulate the configurable parameters on a Twirp client.
-type ClientOptions struct {
- Interceptors []Interceptor
- Hooks *ClientHooks
- pathPrefix *string
- LiteralURLs bool
-}
-
-func (opts *ClientOptions) PathPrefix() string {
- if opts.pathPrefix == nil {
- return "/twirp" // default prefix
+// WithClientHooks defines the hooks for a Twirp client.
+func WithClientHooks(hooks *ClientHooks) ClientOption {
+ return func(opts *ClientOptions) {
+ opts.Hooks = hooks
  }
- return *opts.pathPrefix
 }
 
 // WithClientInterceptors defines the interceptors for a Twirp client.
 func WithClientInterceptors(interceptors ...Interceptor) ClientOption {
- return func(o *ClientOptions) {
- o.Interceptors = append(o.Interceptors, interceptors...)
+ return func(opts *ClientOptions) {
+ opts.Interceptors = append(opts.Interceptors, interceptors...)
  }
 }
 
-// WithClientHooks defines the hooks for a Twirp client.
-func WithClientHooks(hooks *ClientHooks) ClientOption {
- return func(o *ClientOptions) {
- o.Hooks = hooks
+// WithClientPathPrefix specifies a different prefix to use for routing.
+// If not specified, the "/twirp" prefix is used by default.
+// The service must be configured to serve on the same prefix.
+// An empty value "" can be speficied to use no prefix.
+// URL format: "<baseURL>[<prefix>]/<package>.<Service>/<Method>"
+// More info on Twirp docs: https://twitchtv.github.io/twirp/docs/routing.html
+func WithClientPathPrefix(prefix string) ClientOption {
+ return func(opts *ClientOptions) {
+ opts.setOpt("pathPrefix", prefix)
+ opts.pathPrefix = &prefix // for code generated before v8.1.0
+ }
+}
+
+// WithClientLiteralURLs configures the Twirp client to use the exact values
+// as defined in the proto file for Service and Method names,
+// fixing the issue https://github.com/twitchtv/twirp/issues/244, which is manifested
+// when working with Twirp services implemented other languages (e.g. Python) and the proto file definitions
+// are not properly following the [Protobuf Style Guide](https://developers.google.com/protocol-buffers/docs/style#services).
+// By default (false), Go clients modify the routes by CamelCasing the values. For example,
+// with Service: `haberdasher`, Method: `make_hat`, the URLs generated by Go clients are `Haberdasher/MakeHat`,
+// but with this option enabled (true) the client will properly use `haberdasher/make_hat` instead.
+func WithClientLiteralURLs(b bool) ClientOption {
+ return func(opts *ClientOptions) {
+ opts.setOpt("literalURLs", b)
+ opts.LiteralURLs = b // for code generated before v8.1.0
  }
 }
 
@@ -120,28 +134,63 @@ func ChainClientHooks(hooks ...*ClientHooks) *ClientHooks {
  }
 }
 
-// WithClientPathPrefix specifies a different prefix to use for routing.
-// If not specified, the "/twirp" prefix is used by default.
-// The service must be configured to serve on the same prefix.
-// An empty value "" can be speficied to use no prefix.
-// URL format: "<baseURL>[<prefix>]/<package>.<Service>/<Method>"
-// More info on Twirp docs: https://twitchtv.github.io/twirp/docs/routing.html
-func WithClientPathPrefix(prefix string) ClientOption {
- return func(o *ClientOptions) {
- o.pathPrefix = &prefix
+// ClientOptions encapsulate the configurable parameters on a Twirp client.
+// This type is meant to be used only by generated code.
+type ClientOptions struct {
+ // Untyped options map. The methods setOpt and ReadOpt are used to set
+ // and read options. The options are untyped so when a new option is added,
+ // newly generated code can still work with older versions of the runtime.
+ m map[string]interface{}
+
+ Hooks *ClientHooks
+ Interceptors []Interceptor
+
+ // Properties below are only used by code that was
+ // generated by older versions of Twirp (before v8.1.0).
+ // New options with standard types added in the future
+ // don't need new properties, they should use ReadOpt.
+ LiteralURLs bool
+ pathPrefix *string
+}
+
+// ReadOpt extracts an option to a pointer value,
+// returns true if the option exists and was extracted.
+// This method is meant to be used by generated code,
+// keeping the type dependency outside of the runtime.
+//
+// Usage example:
+//
+// opts.setOpt("fooOpt", 123)
+// var foo int
+// ok := opts.ReadOpt("fooOpt", &int)
+//
+func (opts *ClientOptions) ReadOpt(key string, out interface{}) bool {
+ val, ok := opts.m[key]
+ if !ok {
+ return false
+ }
+
+ rout := reflect.ValueOf(out)
+ if rout.Kind() != reflect.Ptr {
+ panic("ReadOpt(key, out); out must be a pointer but it was not")
  }
+ rout.Elem().Set(reflect.ValueOf(val))
+ return true
 }
 
-// WithClientLiteralURLs configures the Twirp client to use the exact values
-// as defined in the proto file for Service and Method names,
-// fixing the issue https://github.com/twitchtv/twirp/issues/244, which is manifested
-// when working with Twirp services implemented other languages (e.g. Python) and the proto file definitions
-// are not properly following the [Protobuf Style Guide](https://developers.google.com/protocol-buffers/docs/style#services).
-// By default (false), Go clients modify the routes by CamelCasing the values. For example,
-// with Service: `haberdasher`, Method: `make_hat`, the URLs generated by Go clients are `Haberdasher/MakeHat`,
-// but with this option enabled (true) the client will properly use `haberdasher/make_hat` instead.
-func WithClientLiteralURLs(b bool) ClientOption {
- return func(o *ClientOptions) {
- o.LiteralURLs = b
+// setOpt adds an option key/value. It is used by ServerOption helpers.
+// The value can be extracted with ReadOpt by passing a pointer to the same type.
+func (opts *ClientOptions) setOpt(key string, val interface{}) {
+ if opts.m == nil {
+ opts.m = make(map[string]interface{})
+ }
+ opts.m[key] = val
+}
+
+// PathPrefix() is used only by clients generated before v8.1.0
+func (opts *ClientOptions) PathPrefix() string {
+ if opts.pathPrefix == nil {
+ return "/twirp" // default prefix
  }
+ return *opts.pathPrefix
 }

client_options_test.go

@@ -20,6 +20,41 @@ import (
  "testing"
 )
 
+func TestClientOptionsReadOpt(t *testing.T) {
+ opts := &ClientOptions{}
+ ok := false
+
+ var fooNum int
+ ok = opts.ReadOpt("fooNum", &fooNum)
+ if ok {
+ t.Errorf("option 'fooNum' does not exist, opts.ReadOpt should have returned false")
+ }
+
+ opts.setOpt("fooNum", 455)
+ ok = opts.ReadOpt("fooNum", &fooNum)
+ if !ok || fooNum != 455 {
+ t.Errorf("option 'fooNum' expected to be 455")
+ }
+
+ var literalURLs bool
+ ok = opts.ReadOpt("literalURLs", &literalURLs)
+ if ok {
+ t.Errorf("option 'literalURLs' does not exist, opts.ReadOpt should have returned false")
+ }
+
+ WithClientLiteralURLs(true)(opts)
+ ok = opts.ReadOpt("literalURLs", &literalURLs)
+ if !ok || !literalURLs {
+ t.Errorf("option 'literalURLs' expected to be true, ok: %v, val: %v", ok, literalURLs)
+ }
+
+ WithClientLiteralURLs(false)(opts)
+ ok = opts.ReadOpt("literalURLs", &literalURLs)
+ if !ok || literalURLs {
+ t.Errorf("option 'literalURLs' expected to be false, ok: %v, val: %v", ok, literalURLs)
+ }
+}
+
 func TestChainClientHooks(t *testing.T) {
  var (
  hook1 = new(ClientHooks)