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core: Add godoc examples for LoadModule
Matthew Holt committed
Dec 10, 2019 at 14:06 UTC
fab5e4372a941ee4259adea9295f49dcadca26a4
2 files changed
+121
-1
context.go
+3
-1
@@ -124,7 +124,9 @@ func (ctx *Context) OnCancel(f func()) {
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// and store them on the same struct. Storing them on the same struct makes for
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// easy garbage collection when your host module is no longer needed.
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//
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-// Loaded modules have already been provisioned and validated.
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+// Loaded modules have already been provisioned and validated. Upon returning
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+// successfully, this method clears the json.RawMessage(s) in the field since
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+// the raw JSON is no longer needed, and this allows the GC to free up memory.
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func (ctx Context) LoadModule(structPointer interface{}, fieldName string) (interface{}, error) {
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val := reflect.ValueOf(structPointer).Elem().FieldByName(fieldName)
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typ := val.Type()
context_test.go
new
+118
@@ -0,0 +1,118 @@
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+// Copyright 2015 Matthew Holt and The Caddy Authors
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+//
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+// Licensed under the Apache License, Version 2.0 (the "License");
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+// you may not use this file except in compliance with the License.
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+// You may obtain a copy of the License at
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+//
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+// http://www.apache.org/licenses/LICENSE-2.0
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+//
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+// Unless required by applicable law or agreed to in writing, software
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+// distributed under the License is distributed on an "AS IS" BASIS,
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+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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+// See the License for the specific language governing permissions and
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+// limitations under the License.
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+
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+package caddy
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+
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+import (
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+ "encoding/json"
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+ "io"
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+)
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+
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+func ExampleContext_LoadModule() {
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+ // this whole first part is just setting up for the example;
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+ // note the struct tags - very important; we specify inline_key
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+ // because that is the only way to know the module name
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+ var ctx Context
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+ myStruct := &struct {
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+ // This godoc comment will appear in module documentation.
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+ GuestModuleRaw json.RawMessage `json:"guest_module,omitempty" caddy:"namespace=example inline_key=name"`
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+
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+ // this is where the decoded module will be stored; in this
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+ // example, we pretend we need an io.Writer but it can be
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+ // any interface type that is useful to you
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+ guestModule io.Writer
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+ }{
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+ GuestModuleRaw: json.RawMessage(`{"name":"module_name","foo":"bar"}`),
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+ }
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+
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+ // if a guest module is provided, we can load it easily
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+ if myStruct.GuestModuleRaw != nil {
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+ mod, err := ctx.LoadModule(myStruct, "GuestModuleRaw")
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+ if err != nil {
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+ // you'd want to actually handle the error here
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+ // return fmt.Errorf("loading guest module: %v", err)
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+ }
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+ // mod contains the loaded and provisioned module,
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+ // it is now ready for us to use
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+ myStruct.guestModule = mod.(io.Writer)
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+ }
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+
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+ // use myStruct.guestModule from now on
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+}
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+
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+func ExampleContext_LoadModule_array() {
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+ // this whole first part is just setting up for the example;
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+ // note the struct tags - very important; we specify inline_key
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+ // because that is the only way to know the module name
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+ var ctx Context
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+ myStruct := &struct {
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+ // This godoc comment will appear in module documentation.
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+ GuestModulesRaw []json.RawMessage `json:"guest_modules,omitempty" caddy:"namespace=example inline_key=name"`
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+
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+ // this is where the decoded module will be stored; in this
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+ // example, we pretend we need an io.Writer but it can be
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+ // any interface type that is useful to you
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+ guestModules []io.Writer
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+ }{
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+ GuestModulesRaw: []json.RawMessage{
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+ json.RawMessage(`{"name":"module1_name","foo":"bar1"}`),
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+ json.RawMessage(`{"name":"module2_name","foo":"bar2"}`),
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+ },
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+ }
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+
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+ // since our input is []json.RawMessage, the output will be []interface{}
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+ mods, err := ctx.LoadModule(myStruct, "GuestModulesRaw")
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+ if err != nil {
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+ // you'd want to actually handle the error here
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+ // return fmt.Errorf("loading guest modules: %v", err)
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+ }
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+ for _, mod := range mods.([]interface{}) {
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+ myStruct.guestModules = append(myStruct.guestModules, mod.(io.Writer))
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+ }
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+
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+ // use myStruct.guestModules from now on
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+}
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+
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+func ExampleContext_LoadModule_map() {
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+ // this whole first part is just setting up for the example;
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+ // note the struct tags - very important; we don't specify
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+ // inline_key because the map key is the module name
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+ var ctx Context
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+ myStruct := &struct {
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+ // This godoc comment will appear in module documentation.
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+ GuestModulesRaw ModuleMap `json:"guest_modules,omitempty" caddy:"namespace=example"`
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+
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+ // this is where the decoded module will be stored; in this
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+ // example, we pretend we need an io.Writer but it can be
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+ // any interface type that is useful to you
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+ guestModules map[string]io.Writer
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+ }{
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+ GuestModulesRaw: ModuleMap{
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+ "module1_name": json.RawMessage(`{"foo":"bar1"}`),
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+ "module2_name": json.RawMessage(`{"foo":"bar2"}`),
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+ },
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+ }
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+
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+ // since our input is map[string]json.RawMessage, the output will be map[string]interface{}
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+ mods, err := ctx.LoadModule(myStruct, "GuestModulesRaw")
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+ if err != nil {
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+ // you'd want to actually handle the error here
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+ // return fmt.Errorf("loading guest modules: %v", err)
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+ }
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+ for modName, mod := range mods.(map[string]interface{}) {
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+ myStruct.guestModules[modName] = mod.(io.Writer)
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+ }
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+
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+ // use myStruct.guestModules from now on
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+}