Use a symbol for the 'scoping' parameter group

common/reviews/api/ts-command-line.api.md

@@ -113,9 +113,9 @@ export abstract class CommandLineParameter {
     readonly environmentVariable: string | undefined;
     // @internal
     _getSupplementaryNotes(supplementaryNotes: string[]): void;
-    readonly groupName: string | undefined;
     abstract get kind(): CommandLineParameterKind;
     readonly longName: string;
+    readonly parameterGroup: string | typeof SCOPING_PARAMETER_GROUP | undefined;
     // @internal
     _parserKey: string | undefined;
     protected reportInvalidData(data: any): never;
@@ -253,7 +253,7 @@ export class DynamicCommandLineParser extends CommandLineParser {
 export interface IBaseCommandLineDefinition {
     description: string;
     environmentVariable?: string;
-    parameterGroupName?: string;
+    parameterGroup?: string | typeof SCOPING_PARAMETER_GROUP;
     parameterLongName: string;
     parameterShortName?: string;
     required?: boolean;
@@ -345,7 +345,7 @@ export abstract class ScopedCommandLineAction extends CommandLineAction {
     get parameters(): ReadonlyArray<CommandLineParameter>;
     // @internal
     _processParsedData(parserOptions: ICommandLineParserOptions, data: _ICommandLineParserData): void;
-    static ScopingParameterGroupName: 'scoping';
+    static readonly ScopingParameterGroup: typeof SCOPING_PARAMETER_GROUP;
 }
 
 ```

libraries/ts-command-line/src/parameters/BaseClasses.ts

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation. All rights reserved. Licensed under the MIT license.
 // See LICENSE in the project root for license information.
 
+import { SCOPING_PARAMETER_GROUP } from '../providers/ScopedCommandLineAction';
 import { IBaseCommandLineDefinition, IBaseCommandLineDefinitionWithArgument } from './CommandLineDefinition';
 
 /**
@@ -53,8 +54,8 @@ export abstract class CommandLineParameter {
   /** {@inheritDoc IBaseCommandLineDefinition.parameterShortName} */
   public readonly shortName: string | undefined;
 
-  /** {@inheritDoc IBaseCommandLineDefinition.parameterGroupName} */
-  public readonly groupName: string | undefined;
+  /** {@inheritDoc IBaseCommandLineDefinition.parameterGroup} */
+  public readonly parameterGroup: string | typeof SCOPING_PARAMETER_GROUP | undefined;
 
   /** {@inheritDoc IBaseCommandLineDefinition.description} */
   public readonly description: string;
@@ -72,7 +73,7 @@ export abstract class CommandLineParameter {
   public constructor(definition: IBaseCommandLineDefinition) {
     this.longName = definition.parameterLongName;
     this.shortName = definition.parameterShortName;
-    this.groupName = definition.parameterGroupName;
+    this.parameterGroup = definition.parameterGroup;
     this.description = definition.description;
     this.required = !!definition.required;
     this.environmentVariable = definition.environmentVariable;

libraries/ts-command-line/src/parameters/CommandLineDefinition.ts

@@ -1,6 +1,8 @@
 // Copyright (c) Microsoft Corporation. All rights reserved. Licensed under the MIT license.
 // See LICENSE in the project root for license information.
 
+import { SCOPING_PARAMETER_GROUP } from '../providers/ScopedCommandLineAction';
+
 /**
  * For use with CommandLineParser, this interface represents a generic command-line parameter
  *
@@ -20,7 +22,7 @@ export interface IBaseCommandLineDefinition {
   /**
    * An optional parameter group name, shown when invoking the tool with "--help"
    */
-  parameterGroupName?: string;
+  parameterGroup?: string | typeof SCOPING_PARAMETER_GROUP;
 
   /**
    * Documentation for the parameter that will be shown when invoking the tool with "--help"

libraries/ts-command-line/src/providers/CommandLineParameterProvider.ts

@@ -27,6 +27,7 @@ import { CommandLineFlagParameter } from '../parameters/CommandLineFlagParameter
 import { CommandLineStringParameter } from '../parameters/CommandLineStringParameter';
 import { CommandLineStringListParameter } from '../parameters/CommandLineStringListParameter';
 import { CommandLineRemainder } from '../parameters/CommandLineRemainder';
+import { SCOPING_PARAMETER_GROUP } from './ScopedCommandLineAction';
 
 /**
  * This is the argparse result data object
@@ -48,16 +49,16 @@ export abstract class CommandLineParameterProvider {
 
   private _parameters: CommandLineParameter[];
   private _parametersByLongName: Map<string, CommandLineParameter>;
-  private _parameterGroupsByName: Map<string, argparse.ArgumentGroup>;
+  private _parameterGroupsByName: Map<string | typeof SCOPING_PARAMETER_GROUP, argparse.ArgumentGroup>;
   private _parametersProcessed: boolean;
   private _remainder: CommandLineRemainder | undefined;
 
   /** @internal */
   // Third party code should not inherit subclasses or call this constructor
   public constructor() {
     this._parameters = [];
-    this._parametersByLongName = new Map<string, CommandLineParameter>();
-    this._parameterGroupsByName = new Map<string, argparse.ArgumentGroup>();
+    this._parametersByLongName = new Map();
+    this._parameterGroupsByName = new Map();
     this._parametersProcessed = false;
   }
 
@@ -448,13 +449,22 @@ export abstract class CommandLineParameterProvider {
     }
 
     let argumentGroup: argparse.ArgumentGroup | undefined;
-    if (parameter.groupName) {
-      argumentGroup = this._parameterGroupsByName.get(parameter.groupName);
+    if (parameter.parameterGroup) {
+      argumentGroup = this._parameterGroupsByName.get(parameter.parameterGroup);
       if (!argumentGroup) {
+        let parameterGroupName: string;
+        if (typeof parameter.parameterGroup === 'string') {
+          parameterGroupName = parameter.parameterGroup;
+        } else if (parameter.parameterGroup === SCOPING_PARAMETER_GROUP) {
+          parameterGroupName = 'scoping';
+        } else {
+          throw new Error('Unexpected parameter group: ' + parameter.parameterGroup);
+        }
+
         argumentGroup = this._getArgumentParser().addArgumentGroup({
-          title: `Optional ${parameter.groupName} arguments`
+          title: `Optional ${parameterGroupName} arguments`
         });
-        this._parameterGroupsByName.set(parameter.groupName, argumentGroup);
+        this._parameterGroupsByName.set(parameter.parameterGroup, argumentGroup);
       }
     } else {
       argumentGroup = this._getArgumentParser();

libraries/ts-command-line/src/providers/ScopedCommandLineAction.ts

@@ -48,6 +48,8 @@ class InternalScopedCommandLineParser extends CommandLineParser {
   }
 }
 
+export const SCOPING_PARAMETER_GROUP: unique symbol = Symbol('scoping');
+
 /**
  * Represents a sub-command that is part of the CommandLineParser command-line.
  * Applications should create subclasses of ScopedCommandLineAction corresponding to
@@ -79,7 +81,7 @@ export abstract class ScopedCommandLineAction extends CommandLineAction {
    * The required group name to apply to all scoping parameters. At least one parameter
    * must be defined with this group name.
    */
-  public static ScopingParameterGroupName: 'scoping' = 'scoping';
+  public static readonly ScopingParameterGroup: typeof SCOPING_PARAMETER_GROUP = SCOPING_PARAMETER_GROUP;
 
   public constructor(options: ICommandLineActionOptions) {
     super(options);
@@ -200,7 +202,7 @@ export abstract class ScopedCommandLineAction extends CommandLineAction {
   /** @internal */
   protected _defineParameter(parameter: CommandLineParameter): void {
     super._defineParameter(parameter);
-    if (parameter.groupName === ScopedCommandLineAction.ScopingParameterGroupName) {
+    if (parameter.parameterGroup === ScopedCommandLineAction.ScopingParameterGroup) {
       this._scopingParameters.push(parameter);
     }
   }

libraries/ts-command-line/src/test/ScopedCommandLineAction.test.ts

@@ -40,7 +40,7 @@ class TestScopedAction extends ScopedCommandLineAction {
 
     this._scopeArg = this.defineStringParameter({
       parameterLongName: '--scope',
-      parameterGroupName: ScopedCommandLineAction.ScopingParameterGroupName,
+      parameterGroup: ScopedCommandLineAction.ScopingParameterGroup,
       argumentName: 'SCOPE',
       description: 'The scope'
     });