Create extension point example

packages/core/PluginManager.ts

@@ -195,6 +195,8 @@ export default class PluginManager {
 
   rootModel?: AbstractRootModel
 
+  extensionPoints: Map<string, Function[]> = new Map()
+
   constructor(initialPlugins: (Plugin | PluginLoadRecord)[] = []) {
     // add the core plugin
     this.addPlugin({ plugin: new CorePlugin(), metadata: { isCore: true } })
@@ -551,4 +553,27 @@ export default class PluginManager {
   ): this {
     return this.addElementType('rpc method', creationCallback)
   }
+  addToExtensionPoint(
+    extensionPointName: string,
+    callback: (arg: unknown) => unknown,
+  ) {
+    if (!this.extensionPoints.has(extensionPointName)) {
+      this.extensionPoints.set(extensionPointName, [])
+    }
+    const ep = this.extensionPoints.get(extensionPointName)
+    if (ep) {
+      // always true
+      ep.push(callback)
+    }
+  }
+  evaluateExtensionPoint(extensionPointName: string, startingArgs?: unknown) {
+    const ep = this.extensionPoints.get(extensionPointName)
+    let accumulator = startingArgs
+    if (ep) {
+      for (const callback of ep) {
+        accumulator = callback(accumulator)
+      }
+    }
+    return accumulator
+  }
 }

plugins/linear-genome-view/src/index.ts

@@ -32,6 +32,7 @@ import {
   configSchema as linearBasicDisplayConfigSchemaFactory,
   modelFactory as linearBasicDisplayModelFactory,
 } from './LinearBasicDisplay'
+import { IAnyModelType, types } from 'mobx-state-tree'
 
 export default class LinearGenomeViewPlugin extends Plugin {
   name = 'LinearGenomeViewPlugin'
@@ -117,6 +118,19 @@ export default class LinearGenomeViewPlugin extends Plugin {
           ),
         }),
     )
+
+    pluginManager.addToExtensionPoint(
+      'Core-extendSessionModel',
+      sessionModel => {
+        console.log('foopy')
+        return types.compose(
+          sessionModel as IAnyModelType,
+          types.model('HelloWorld', {
+            foopy: types.optional(types.string, 'lol'),
+          }),
+        )
+      },
+    )
   }
 
   configure(pluginManager: PluginManager) {

products/jbrowse-cli/README.md

@@ -31,15 +31,16 @@ It is likely preferable in most cases to install the tools first however
 ## Commands
 
 <!-- commands -->
-* [`jbrowse add-assembly SEQUENCE`](#jbrowse-add-assembly-sequence)
-* [`jbrowse add-connection CONNECTIONURLORPATH`](#jbrowse-add-connection-connectionurlorpath)
-* [`jbrowse add-track TRACK`](#jbrowse-add-track-track)
-* [`jbrowse add-track-json TRACK`](#jbrowse-add-track-json-track)
-* [`jbrowse admin-server`](#jbrowse-admin-server)
-* [`jbrowse create LOCALPATH`](#jbrowse-create-localpath)
-* [`jbrowse help [COMMAND]`](#jbrowse-help-command)
-* [`jbrowse set-default-session`](#jbrowse-set-default-session)
-* [`jbrowse upgrade [LOCALPATH]`](#jbrowse-upgrade-localpath)
+
+- [`jbrowse add-assembly SEQUENCE`](#jbrowse-add-assembly-sequence)
+- [`jbrowse add-connection CONNECTIONURLORPATH`](#jbrowse-add-connection-connectionurlorpath)
+- [`jbrowse add-track TRACK`](#jbrowse-add-track-track)
+- [`jbrowse add-track-json TRACK`](#jbrowse-add-track-json-track)
+- [`jbrowse admin-server`](#jbrowse-admin-server)
+- [`jbrowse create LOCALPATH`](#jbrowse-create-localpath)
+- [`jbrowse help [COMMAND]`](#jbrowse-help-command)
+- [`jbrowse set-default-session`](#jbrowse-set-default-session)
+- [`jbrowse upgrade [LOCALPATH]`](#jbrowse-upgrade-localpath)
 
 ## `jbrowse add-assembly SEQUENCE`
 
@@ -70,7 +71,7 @@ OPTIONS
       show CLI help
 
   -l, --load=copy|symlink|move|inPlace
-      Required flag when using a local file. Choose how to manage the data directory. Copy, symlink, or move the data 
+      Required flag when using a local file. Choose how to manage the data directory. Copy, symlink, or move the data
       directory to the JBrowse directory. Or use inPlace to modify the config without doing any file operations
 
   -n, --name=name
@@ -179,11 +180,11 @@ EXAMPLES
   $ jbrowse add-connection http://mysite.com/jbrowse/data/
   $ jbrowse add-connection http://mysite.com/jbrowse/custom_data_folder/ --type JBrowse1Connection
   $ jbrowse add-connection http://mysite.com/path/to/hub.txt --assemblyName hg19
-  $ jbrowse add-connection http://mysite.com/path/to/custom_hub_name.txt --type UCSCTrackHubConnection --assemblyName 
+  $ jbrowse add-connection http://mysite.com/path/to/custom_hub_name.txt --type UCSCTrackHubConnection --assemblyName
   hg19
-  $ jbrowse add-connection http://mysite.com/path/to/custom --type custom --config 
+  $ jbrowse add-connection http://mysite.com/path/to/custom --type custom --config
   '{"uri":{"url":"https://mysite.com/path/to/custom"}}' --assemblyName hg19
-  $ jbrowse add-connection https://mysite.com/path/to/hub.txt --connectionId newId --name newName --target 
+  $ jbrowse add-connection https://mysite.com/path/to/hub.txt --connectionId newId --name newName --target
   /path/to/jb2/installation/config.json
 ```
 
@@ -254,7 +255,7 @@ EXAMPLES
   # no --load flag to add literal URL for this track to config.json
   $ jbrowse add-track https://mywebsite.com/my.bam
 
-  # --load move to move the file 
+  # --load move to move the file
   $ jbrowse add-track /path/to/my.bam --name 'New Track' --load move
 
   # --load inPlace puts /url/relative/path.bam in the config without performing any file operations
@@ -397,7 +398,7 @@ OPTIONS
 
 EXAMPLES
   $ jbrowse set-default-session --session /path/to/default/session.json
-  $ jbrowse set-default-session --target /path/to/jb2/installation/config.json --view LinearGenomeView --tracks track1, 
+  $ jbrowse set-default-session --target /path/to/jb2/installation/config.json --view LinearGenomeView --tracks track1,
   track2, track3
   $ jbrowse set-default-session --view LinearGenomeView, --name newName --viewId view-no-tracks
   $ jbrowse set-default-session --currentSession # Prints out current default session
@@ -438,6 +439,7 @@ EXAMPLES
 ```
 
 _See code: [src/commands/upgrade.ts](https://github.com/GMOD/jbrowse-components/blob/v1.3.2/products/jbrowse-cli/src/commands/upgrade.ts)_
+
 <!-- commandsstop -->
 
 ## Debugging

products/jbrowse-web/src/sessionModelFactory.ts

@@ -30,6 +30,7 @@ import {
   types,
   walk,
   Instance,
+  IAnyModelType,
 } from 'mobx-state-tree'
 import PluginManager from '@jbrowse/core/PluginManager'
 import RpcManager from '@jbrowse/core/rpc/RpcManager'
@@ -51,7 +52,7 @@ export default function sessionModelFactory(
   assemblyConfigSchemasType = types.frozen(), // if not using sessionAssemblies
 ) {
   const minDrawerWidth = 128
-  const sessionModel = types
+  let sessionModel = types
     .model('JBrowseWebSessionModel', {
       id: types.optional(types.identifier, shortid()),
       name: types.string,
@@ -695,6 +696,11 @@ export default function sessionModelFactory(
       },
     }))
 
+  sessionModel = pluginManager.evaluateExtensionPoint(
+    'Core-extendSessionModel',
+    sessionModel,
+  ) as IAnyModelType
+
   return types.snapshotProcessor(sessionModel, {
     // @ts-ignore
     preProcessor(snapshot) {