Turn CLI commands into objects, self register subcommands (#935)

Usages of `RootCommand` no longer need to initialize a new instance, nor register subcommands.

pkl-cli/src/main/kotlin/org/pkl/cli/Main.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,26 +17,10 @@
 
 package org.pkl.cli
 
-import com.github.ajalt.clikt.core.subcommands
 import org.pkl.cli.commands.*
 import org.pkl.commons.cli.cliMain
-import org.pkl.core.Release
 
 /** Main method of the Pkl CLI (command-line evaluator and REPL). */
 internal fun main(args: Array<String>) {
-  cliMain {
+  cliMain { RootCommand.main(args) }
-    val version = Release.current().versionInfo()
-    val helpLink = "${Release.current().documentation().homepage()}pkl-cli/index.html#usage"
-    RootCommand("pkl", version, helpLink)
-      .subcommands(
-        EvalCommand(helpLink),
-        ReplCommand(helpLink),
-        ServerCommand(helpLink),
-        TestCommand(helpLink),
-        ProjectCommand(helpLink),
-        DownloadPackageCommand(helpLink),
-        AnalyzeCommand(helpLink),
-      )
-      .main(args)
-  }
 }

pkl-cli/src/main/kotlin/org/pkl/cli/commands/AnalyzeCommand.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,42 +25,40 @@ import org.pkl.cli.CliImportAnalyzerOptions
 import org.pkl.commons.cli.commands.ModulesCommand
 import org.pkl.commons.cli.commands.single
 
-class AnalyzeCommand(helpLink: String) :
+object AnalyzeCommand :
   NoOpCliktCommand(
     name = "analyze",
     help = "Commands related to static analysis",
-    epilog = "For more information, visit $helpLink"
+    epilog = "For more information, visit $helpLink",
   ) {
   init {
-    subcommands(AnalyzeImportsCommand(helpLink))
+    subcommands(AnalyzeImportsCommand)
-  }
+  }
-
+}
-  companion object {
+
-    class AnalyzeImportsCommand(helpLink: String) :
+object AnalyzeImportsCommand :
-      ModulesCommand(
+  ModulesCommand(
-        name = "imports",
+    name = "imports",
-        helpLink = helpLink,
+    helpLink = helpLink,
-        help = "Prints the graph of modules imported by the input module(s)."
+    help = "Prints the graph of modules imported by the input module(s).",
-      ) {
+  ) {
-
+
-      private val outputPath: Path? by
+  private val outputPath: Path? by
-        option(
+    option(
-            names = arrayOf("-o", "--output-path"),
+        names = arrayOf("-o", "--output-path"),
-            metavar = "<path>",
+        metavar = "<path>",
-            help = "File path where the output file is placed."
+        help = "File path where the output file is placed.",
-          )
+      )
-          .path()
+      .path()
-          .single()
+      .single()
-
+
-      override fun run() {
+  override fun run() {
-        val options =
+    val options =
-          CliImportAnalyzerOptions(
+      CliImportAnalyzerOptions(
-            base = baseOptions.baseOptions(modules, projectOptions),
+        base = baseOptions.baseOptions(modules, projectOptions),
-            outputFormat = baseOptions.format,
+        outputFormat = baseOptions.format,
-            outputPath = outputPath
+        outputPath = outputPath,
-          )
+      )
-        CliImportAnalyzer(options).run()
+    CliImportAnalyzer(options).run()
-      }
-    }
   }
 }

pkl-cli/src/main/kotlin/org/pkl/cli/commands/DownloadPackageCommand.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,7 +27,7 @@ import org.pkl.commons.cli.commands.ProjectOptions
 import org.pkl.commons.cli.commands.single
 import org.pkl.core.packages.PackageUri
 
-class DownloadPackageCommand(helpLink: String) :
+object DownloadPackageCommand :
   BaseCommand(
     name = "download-package",
     helpLink = helpLink,
@@ -44,7 +44,7 @@ class DownloadPackageCommand(helpLink: String) :
     $ pkl download-package package://example.com/package1@1.0.0 package://example.com/package2@1.0.0 
     ```
   """
-        .trimIndent()
+        .trimIndent(),
   ) {
   private val projectOptions by ProjectOptions()
 
@@ -56,7 +56,7 @@ class DownloadPackageCommand(helpLink: String) :
   private val noTransitive: Boolean by
     option(
         names = arrayOf("--no-transitive"),
-        help = "Skip downloading transitive dependencies of a package"
+        help = "Skip downloading transitive dependencies of a package",
       )
       .single()
       .flag()
@@ -65,7 +65,7 @@ class DownloadPackageCommand(helpLink: String) :
     CliPackageDownloader(
         baseOptions.baseOptions(emptyList(), projectOptions),
         packageUris,
-        noTransitive
+        noTransitive,
       )
       .run()
   }

pkl-cli/src/main/kotlin/org/pkl/cli/commands/EvalCommand.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,17 +24,13 @@ import org.pkl.cli.CliEvaluatorOptions
 import org.pkl.commons.cli.commands.ModulesCommand
 import org.pkl.commons.cli.commands.single
 
-class EvalCommand(helpLink: String) :
+object EvalCommand :
-  ModulesCommand(
+  ModulesCommand(name = "eval", help = "Render pkl module(s)", helpLink = helpLink) {
-    name = "eval",
-    help = "Render pkl module(s)",
-    helpLink = helpLink,
-  ) {
   private val outputPath: String? by
     option(
         names = arrayOf("-o", "--output-path"),
         metavar = "<path>",
-        help = "File path where the output file is placed."
+        help = "File path where the output file is placed.",
       )
       .single()
 
@@ -43,7 +39,7 @@ class EvalCommand(helpLink: String) :
         names = arrayOf("--module-output-separator"),
         metavar = "<string>",
         help =
-          "Separator to use when multiple module outputs are written to the same file. (default: ---)"
+          "Separator to use when multiple module outputs are written to the same file. (default: ---)",
       )
       .single()
       .default("---")
@@ -52,7 +48,7 @@ class EvalCommand(helpLink: String) :
     option(
         names = arrayOf("-x", "--expression"),
         metavar = "<expression>",
-        help = "Expression to be evaluated within the module."
+        help = "Expression to be evaluated within the module.",
       )
       .single()
 
@@ -60,7 +56,7 @@ class EvalCommand(helpLink: String) :
     option(
         names = arrayOf("-m", "--multiple-file-output-path"),
         metavar = "<path>",
-        help = "Directory where a module's multiple file output is placed."
+        help = "Directory where a module's multiple file output is placed.",
       )
       .single()
       .validate {
@@ -81,7 +77,7 @@ class EvalCommand(helpLink: String) :
         outputFormat = baseOptions.format,
         moduleOutputSeparator = moduleOutputSeparator,
         multipleFileOutputPath = multipleFileOutputPath,
-        expression = expression ?: CliEvaluatorOptions.defaults.expression
+        expression = expression ?: CliEvaluatorOptions.defaults.expression,
       )
     CliEvaluator(options).run()
   }

pkl-cli/src/main/kotlin/org/pkl/cli/commands/ProjectCommand.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -31,119 +31,117 @@ import org.pkl.commons.cli.commands.BaseCommand
 import org.pkl.commons.cli.commands.TestOptions
 import org.pkl.commons.cli.commands.single
 
-class ProjectCommand(helpLink: String) :
+private const val NEWLINE = '\u0085'
+
+object ProjectCommand :
   NoOpCliktCommand(
     name = "project",
     help = "Run commands related to projects",
-    epilog = "For more information, visit $helpLink"
+    epilog = "For more information, visit $helpLink",
   ) {
   init {
-    subcommands(ResolveCommand(helpLink), PackageCommand(helpLink))
+    subcommands(ResolveCommand, PackageCommand)
-  }
+  }
-
+}
-  companion object {
+
-    class ResolveCommand(helpLink: String) :
+object ResolveCommand :
-      BaseCommand(
+  BaseCommand(
-        name = "resolve",
+    name = "resolve",
-        helpLink = helpLink,
+    helpLink = helpLink,
-        help =
+    help =
-          """
+      """
-        Resolve dependencies for project(s)
+    Resolve dependencies for project(s)
-        
+    
-        This command takes the `dependencies` of `PklProject`s, and writes the
+    This command takes the `dependencies` of `PklProject`s, and writes the
-        resolved versions to `PklProject.deps.json` files.
+    resolved versions to `PklProject.deps.json` files.
-        
+    
-        Examples:
+    Examples:
-
+
-        ```
+    ```
-        # Search the current working directory for a project, and resolve its dependencies.
+    # Search the current working directory for a project, and resolve its dependencies.
-        $ pkl project resolve
+    $ pkl project resolve
-
+
-        # Resolve dependencies for all projects within the `packages/` directory.
+    # Resolve dependencies for all projects within the `packages/` directory.
-        $ pkl project resolve packages/*/
+    $ pkl project resolve packages/*/
-        ```
+    ```
-        """,
+    """,
-      ) {
+  ) {
-      private val projectDirs: List<Path> by
+  private val projectDirs: List<Path> by
-        argument("<dir>", "The project directories to resolve dependencies for").path().multiple()
+    argument("<dir>", "The project directories to resolve dependencies for").path().multiple()
-
+
-      override fun run() {
+  override fun run() {
-        CliProjectResolver(baseOptions.baseOptions(emptyList()), projectDirs).run()
+    CliProjectResolver(baseOptions.baseOptions(emptyList()), projectDirs).run()
-      }
+  }
-    }
+}
-
+
-    private const val NEWLINE = '\u0085'
+object PackageCommand :
-
+  BaseCommand(
-    class PackageCommand(helpLink: String) :
+    name = "package",
-      BaseCommand(
+    helpLink = helpLink,
-        name = "package",
+    help =
-        helpLink = helpLink,
+      """
-        help =
+      Verify package(s), and prepare package artifacts to be published.
-          """
+
-          Verify package(s), and prepare package artifacts to be published.
+      This command runs a project's api tests, as defined by `apiTests` in `PklProject`.
-  
+      Additionally, it verifies that all imports resolve to paths that are local to the project.
-          This command runs a project's api tests, as defined by `apiTests` in `PklProject`.
+
-          Additionally, it verifies that all imports resolve to paths that are local to the project.
+      Finally, this command writes the following artifacts into the output directory specified by the output path.
-  
+
-          Finally, this command writes the following artifacts into the output directory specified by the output path.
+        - `name@version` - dependency metadata$NEWLINE
-  
+        - `name@version.sha256` - dependency metadata's SHA-256 checksum$NEWLINE
-            - `name@version` - dependency metadata$NEWLINE
+        - `name@version.zip` - package archive$NEWLINE
-            - `name@version.sha256` - dependency metadata's SHA-256 checksum$NEWLINE
+        - `name@version.zip.sha256` - package archive's SHA-256 checksum
-            - `name@version.zip` - package archive$NEWLINE
+
-            - `name@version.zip.sha256` - package archive's SHA-256 checksum
+      The output path option accepts the following placeholders:
-  
+
-          The output path option accepts the following placeholders:
+        - %{name}: The display name of the package$NEWLINE
-  
+        - %{version}: The version of the package
-            - %{name}: The display name of the package$NEWLINE
+
-            - %{version}: The version of the package
+      If a project has local project dependencies, the depended upon project directories must also
-  
+      be included as arguments to this command.
-          If a project has local project dependencies, the depended upon project directories must also
+
-          be included as arguments to this command.
+      Examples:
-  
+
-          Examples:
+      ```
-  
+      # Search the current working directory for a project, and package it.
-          ```
+      $ pkl project package
-          # Search the current working directory for a project, and package it.
+
-          $ pkl project package
+      # Package all projects within the `packages/` directory.
-  
+      $ pkl project package packages/*/
-          # Package all projects within the `packages/` directory.
+      ```
-          $ pkl project package packages/*/
+      """
-          ```
+        .trimIndent(),
-          """
+  ) {
-            .trimIndent(),
+  private val testOptions by TestOptions()
-      ) {
+
-      private val testOptions by TestOptions()
+  private val projectDirs: List<Path> by
-
+    argument("<dir>", "The project directories to package").path().multiple()
-      private val projectDirs: List<Path> by
+
-        argument("<dir>", "The project directories to package").path().multiple()
+  private val outputPath: String by
-
+    option(
-      private val outputPath: String by
+        names = arrayOf("--output-path"),
-        option(
+        help = "The directory to write artifacts to",
-            names = arrayOf("--output-path"),
+        metavar = "<path>",
-            help = "The directory to write artifacts to",
+      )
-            metavar = "<path>"
+      .single()
-          )
+      .default(".out/%{name}@%{version}")
-          .single()
+
-          .default(".out/%{name}@%{version}")
+  private val skipPublishCheck: Boolean by
-
+    option(
-      private val skipPublishCheck: Boolean by
+        names = arrayOf("--skip-publish-check"),
-        option(
+        help = "Skip checking if a package has already been published with different contents",
-            names = arrayOf("--skip-publish-check"),
+      )
-            help = "Skip checking if a package has already been published with different contents",
+      .single()
-          )
+      .flag()
-          .single()
+
-          .flag()
+  override fun run() {
-
+    CliProjectPackager(
-      override fun run() {
+        baseOptions.baseOptions(emptyList()),
-        CliProjectPackager(
+        projectDirs,
-            baseOptions.baseOptions(emptyList()),
+        testOptions.cliTestOptions,
-            projectDirs,
+        outputPath,
-            testOptions.cliTestOptions,
+        skipPublishCheck,
-            outputPath,
+      )
-            skipPublishCheck
+      .run()
-          )
-          .run()
-      }
-    }
   }
 }

pkl-cli/src/main/kotlin/org/pkl/cli/commands/ReplCommand.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,12 +21,8 @@ import org.pkl.cli.CliRepl
 import org.pkl.commons.cli.commands.BaseCommand
 import org.pkl.commons.cli.commands.ProjectOptions
 
-class ReplCommand(helpLink: String) :
+object ReplCommand :
-  BaseCommand(
+  BaseCommand(name = "repl", help = "Start a REPL session", helpLink = helpLink) {
-    name = "repl",
-    help = "Start a REPL session",
-    helpLink = helpLink,
-  ) {
   private val projectOptions by ProjectOptions()
 
   override fun run() {

pkl-cli/src/main/kotlin/org/pkl/cli/commands/RootCommand.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,16 +17,20 @@ package org.pkl.cli.commands
 
 import com.github.ajalt.clikt.core.NoOpCliktCommand
 import com.github.ajalt.clikt.core.context
+import com.github.ajalt.clikt.core.subcommands
 import com.github.ajalt.clikt.parameters.options.versionOption
+import org.pkl.core.Release
 
-class RootCommand(name: String, version: String, helpLink: String) :
+internal val helpLink = "${Release.current().documentation.homepage}pkl-cli/index.html#usage"
+
+object RootCommand :
   NoOpCliktCommand(
-    name = name,
+    name = "pkl",
     printHelpOnEmptyArgs = true,
     epilog = "For more information, visit $helpLink",
   ) {
   init {
-    versionOption(version, names = setOf("-v", "--version"), message = { it })
+    versionOption(Release.current().versionInfo, names = setOf("-v", "--version"), message = { it })
 
     context {
       correctionSuggestor = { given, possible ->
@@ -35,5 +39,15 @@ class RootCommand(name: String, version: String, helpLink: String) :
         } else possible
       }
     }
+
+    subcommands(
+      EvalCommand,
+      ReplCommand,
+      ServerCommand,
+      TestCommand,
+      ProjectCommand,
+      DownloadPackageCommand,
+      AnalyzeCommand,
+    )
   }
 }

pkl-cli/src/main/kotlin/org/pkl/cli/commands/ServerCommand.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,11 +19,11 @@ import com.github.ajalt.clikt.core.CliktCommand
 import org.pkl.cli.CliServer
 import org.pkl.commons.cli.CliBaseOptions
 
-class ServerCommand(helpLink: String) :
+object ServerCommand :
   CliktCommand(
     name = "server",
     help = "Run as a server that communicates over standard input/output",
-    epilog = "For more information, visit $helpLink"
+    epilog = "For more information, visit $helpLink",
   ) {
 
   override fun run() {

pkl-cli/src/main/kotlin/org/pkl/cli/commands/TestCommand.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,7 +26,7 @@ import org.pkl.commons.cli.commands.BaseOptions
 import org.pkl.commons.cli.commands.ProjectOptions
 import org.pkl.commons.cli.commands.TestOptions
 
-class TestCommand(helpLink: String) :
+object TestCommand :
   BaseCommand(name = "test", help = "Run tests within the given module(s)", helpLink = helpLink) {
   val modules: List<URI> by
     argument(name = "<modules>", help = "Module paths or URIs to evaluate.")
@@ -40,7 +40,7 @@ class TestCommand(helpLink: String) :
   override fun run() {
     CliTestRunner(
         options = baseOptions.baseOptions(modules, projectOptions),
-        testOptions = testOptions.cliTestOptions
+        testOptions = testOptions.cliTestOptions,
       )
       .run()
   }

pkl-cli/src/test/kotlin/org/pkl/cli/CliMainTest.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,7 +16,6 @@
 package org.pkl.cli
 
 import com.github.ajalt.clikt.core.BadParameterValue
-import com.github.ajalt.clikt.core.subcommands
 import java.nio.file.Path
 import kotlin.io.path.createDirectory
 import kotlin.io.path.createSymbolicLinkPointingTo
@@ -27,35 +26,34 @@ import org.junit.jupiter.api.assertThrows
 import org.junit.jupiter.api.condition.DisabledOnOs
 import org.junit.jupiter.api.condition.OS
 import org.junit.jupiter.api.io.TempDir
-import org.pkl.cli.commands.AnalyzeCommand
 import org.pkl.cli.commands.EvalCommand
 import org.pkl.cli.commands.RootCommand
 import org.pkl.commons.writeString
+import org.pkl.core.Release
 
 class CliMainTest {
 
-  private val evalCmd = EvalCommand("")
-  private val analyzeCommand = AnalyzeCommand("")
-  private val cmd = RootCommand("pkl", "pkl version 1", "").subcommands(evalCmd, analyzeCommand)
-
   @Test
   fun `duplicate CLI option produces meaningful error message`(@TempDir tempDir: Path) {
     val inputFile = tempDir.resolve("test.pkl").writeString("").toString()
 
     assertThatCode {
-        cmd.parse(arrayOf("eval", "--output-path", "path1", "--output-path", "path2", inputFile))
+        RootCommand.parse(
+          arrayOf("eval", "--output-path", "path1", "--output-path", "path2", inputFile)
+        )
       }
       .hasMessage("Invalid value for \"--output-path\": Option cannot be repeated")
 
     assertThatCode {
-        cmd.parse(arrayOf("eval", "-o", "path1", "--output-path", "path2", inputFile))
+        RootCommand.parse(arrayOf("eval", "-o", "path1", "--output-path", "path2", inputFile))
       }
       .hasMessage("Invalid value for \"--output-path\": Option cannot be repeated")
   }
 
   @Test
   fun `eval requires at least one file`() {
-    assertThatCode { cmd.parse(arrayOf("eval")) }.hasMessage("""Missing argument "<modules>"""")
+    assertThatCode { RootCommand.parse(arrayOf("eval")) }
+      .hasMessage("""Missing argument "<modules>"""")
   }
 
   // Can't reliably create symlinks on Windows.
@@ -76,7 +74,7 @@ class CliMainTest {
     val inputFile = tempDir.resolve("test.pkl").writeString(code).toString()
     val outputFile = makeSymdir(tempDir, "out", "linkOut").resolve("test.pkl").toString()
 
-    assertThatCode { cmd.parse(arrayOf("eval", inputFile, "-o", outputFile)) }
+    assertThatCode { RootCommand.parse(arrayOf("eval", inputFile, "-o", outputFile)) }
       .doesNotThrowAnyException()
   }
 
@@ -87,22 +85,24 @@ class CliMainTest {
     val error =
       """Invalid value for "--multiple-file-output-path": Option is mutually exclusive with -o, --output-path and -x, --expression."""
 
-    assertThatCode { cmd.parse(arrayOf("eval", "-m", testOut, "-x", "x", testIn)) }
+    assertThatCode { RootCommand.parse(arrayOf("eval", "-m", testOut, "-x", "x", testIn)) }
       .hasMessage(error)
 
-    assertThatCode { cmd.parse(arrayOf("eval", "-m", testOut, "-o", "/tmp/test", testIn)) }
+    assertThatCode { RootCommand.parse(arrayOf("eval", "-m", testOut, "-o", "/tmp/test", testIn)) }
       .hasMessage(error)
   }
 
   @Test
   fun `showing version works`() {
-    assertThatCode { cmd.parse(arrayOf("--version")) }.hasMessage("pkl version 1")
+    assertThatCode { RootCommand.parse(arrayOf("--version")) }
+      .hasMessage(Release.current().versionInfo)
   }
 
   @Test
   fun `file paths get parsed into URIs`(@TempDir tempDir: Path) {
-    cmd.parse(arrayOf("eval", makeInput(tempDir, "my file.txt")))
+    RootCommand.parse(arrayOf("eval", makeInput(tempDir, "my file.txt")))
 
+    val evalCmd = RootCommand.registeredSubcommands().filterIsInstance<EvalCommand>().first()
     val modules = evalCmd.baseOptions.baseOptions(evalCmd.modules).normalizedSourceModules
     assertThat(modules).hasSize(1)
     assertThat(modules[0].path).endsWith("my file.txt")
@@ -110,7 +110,8 @@ class CliMainTest {
 
   @Test
   fun `invalid URIs are not accepted`() {
-    val ex = assertThrows<BadParameterValue> { cmd.parse(arrayOf("eval", "file:my file.txt")) }
+    val ex =
+      assertThrows<BadParameterValue> { RootCommand.parse(arrayOf("eval", "file:my file.txt")) }
 
     assertThat(ex.message).contains("URI `file:my file.txt` has invalid syntax")
   }

pkl-cli/src/test/kotlin/org/pkl/cli/CliTestRunnerTest.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,18 +16,16 @@
 package org.pkl.cli
 
 import com.github.ajalt.clikt.core.MissingArgument
-import com.github.ajalt.clikt.core.subcommands
 import java.io.StringWriter
 import java.io.Writer
 import java.net.URI
 import java.nio.file.Path
-import java.util.Locale
+import java.util.*
 import org.assertj.core.api.Assertions.assertThat
 import org.assertj.core.api.Assertions.assertThatCode
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.assertThrows
 import org.junit.jupiter.api.io.TempDir
-import org.pkl.cli.commands.EvalCommand
 import org.pkl.cli.commands.RootCommand
 import org.pkl.commons.cli.CliBaseOptions
 import org.pkl.commons.cli.CliException
@@ -35,7 +33,6 @@ import org.pkl.commons.cli.CliTestOptions
 import org.pkl.commons.readString
 import org.pkl.commons.toUri
 import org.pkl.commons.writeString
-import org.pkl.core.Release
 
 class CliTestRunnerTest {
   @Test
@@ -381,7 +378,7 @@ class CliTestRunnerTest {
     val opts =
       CliBaseOptions(
         sourceModules = listOf(input.toUri(), input2.toUri()),
-        settings = URI("pkl:settings")
+        settings = URI("pkl:settings"),
       )
     val testOpts = CliTestOptions(junitDir = tempDir)
     val runner = CliTestRunner(opts, testOpts, noopWriter, noopWriter)
@@ -391,12 +388,7 @@ class CliTestRunnerTest {
   @Test
   fun `no source modules specified has same message as pkl eval`() {
     val e1 = assertThrows<CliException> { CliTestRunner(CliBaseOptions(), CliTestOptions()).run() }
-    val e2 =
+    val e2 = assertThrows<MissingArgument> { RootCommand.parse(listOf("eval")) }
-      assertThrows<MissingArgument> {
-        val rootCommand =
-          RootCommand("pkl", Release.current().versionInfo(), "").subcommands(EvalCommand(""))
-        rootCommand.parse(listOf("eval"))
-      }
     assertThat(e1).hasMessageContaining("Missing argument \"<modules>\"")
     assertThat(e1.message!!.replace("test", "eval")).isEqualTo(e2.helpMessage())
   }

pkl-codegen-java/src/main/kotlin/org/pkl/codegen/java/Main.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -28,10 +28,10 @@ import org.pkl.core.Release
 
 /** Main method for the Java code generator CLI. */
 internal fun main(args: Array<String>) {
-  cliMain { PklJavaCodegenCommand().main(args) }
+  cliMain { PklJavaCodegenCommand.main(args) }
 }
 
-class PklJavaCodegenCommand :
+object PklJavaCodegenCommand :
   ModulesCommand(
     name = "pkl-codegen-java",
     helpLink = Release.current().documentation().homepage(),
@@ -43,7 +43,7 @@ class PklJavaCodegenCommand :
     option(
         names = arrayOf("-o", "--output-dir"),
         metavar = "<path>",
-        help = "The directory where generated source code is placed."
+        help = "The directory where generated source code is placed.",
       )
       .path()
       .default(defaults.outputDir)
@@ -52,7 +52,7 @@ class PklJavaCodegenCommand :
     option(
         names = arrayOf("--indent"),
         metavar = "<chars>",
-        help = "The characters to use for indenting generated source code."
+        help = "The characters to use for indenting generated source code.",
       )
       .default(defaults.indent)
 
@@ -61,21 +61,21 @@ class PklJavaCodegenCommand :
         names = arrayOf("--generate-getters"),
         help =
           "Whether to generate public getter methods and " +
-            "private final fields instead of public final fields."
+            "private final fields instead of public final fields.",
       )
       .flag()
 
   private val generateJavadoc: Boolean by
     option(
         names = arrayOf("--generate-javadoc"),
-        help = "Whether to preserve Pkl doc comments by generating corresponding Javadoc comments."
+        help = "Whether to preserve Pkl doc comments by generating corresponding Javadoc comments.",
       )
       .flag()
 
   private val generateSpringBoot: Boolean by
     option(
         names = arrayOf("--generate-spring-boot"),
-        help = "Whether to generate config classes for use with Spring Boot."
+        help = "Whether to generate config classes for use with Spring Boot.",
       )
       .flag()
 
@@ -83,7 +83,7 @@ class PklJavaCodegenCommand :
     option(
         names = arrayOf("--params-annotation"),
         help =
-          "Fully qualified name of the annotation type to use for annotating constructor parameters with their name."
+          "Fully qualified name of the annotation type to use for annotating constructor parameters with their name.",
       )
       .defaultLazy(
         "`none` if `--generate-spring-boot` is set, `org.pkl.config.java.mapper.Named` otherwise"
@@ -100,13 +100,13 @@ class PklJavaCodegenCommand :
       The specified annotation type must be annotated with `@java.lang.annotation.Target(ElementType.TYPE_USE)`
       or the generated code may not compile.
     """
-          .trimIndent()
+          .trimIndent(),
     )
 
   private val implementSerializable: Boolean by
     option(
         names = arrayOf("--implement-serializable"),
-        help = "Whether to generate classes that implement java.io.Serializable."
+        help = "Whether to generate classes that implement java.io.Serializable.",
       )
       .flag()
 
@@ -121,7 +121,7 @@ class PklJavaCodegenCommand :
             With this option, you can override or modify the default names, renaming entire
             classes or just their packages.
           """
-            .trimIndent()
+            .trimIndent(),
       )
       .associate()
 
@@ -137,7 +137,7 @@ class PklJavaCodegenCommand :
         paramsAnnotation = if (paramsAnnotation == "none") null else paramsAnnotation,
         nonNullAnnotation = nonNullAnnotation,
         implementSerializable = implementSerializable,
-        renames = renames
+        renames = renames,
       )
     CliJavaCodeGenerator(options).run()
   }

pkl-codegen-kotlin/src/main/kotlin/org/pkl/codegen/kotlin/Main.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -31,10 +31,10 @@ import org.pkl.core.Release
 
 /** Main method for the Kotlin code generator CLI. */
 internal fun main(args: Array<String>) {
-  cliMain { PklKotlinCodegenCommand().main(args) }
+  cliMain { PklKotlinCodegenCommand.main(args) }
 }
 
-class PklKotlinCodegenCommand :
+object PklKotlinCodegenCommand :
   ModulesCommand(
     name = "pkl-codegen-kotlin",
     helpLink = Release.current().documentation().homepage(),
@@ -46,7 +46,7 @@ class PklKotlinCodegenCommand :
     option(
         names = arrayOf("-o", "--output-dir"),
         metavar = "<path>",
-        help = "The directory where generated source code is placed."
+        help = "The directory where generated source code is placed.",
       )
       .path()
       .default(defaults.outputDir)
@@ -55,28 +55,28 @@ class PklKotlinCodegenCommand :
     option(
         names = arrayOf("--indent"),
         metavar = "<chars>",
-        help = "The characters to use for indenting generated source code."
+        help = "The characters to use for indenting generated source code.",
       )
       .default(defaults.indent)
 
   private val generateKdoc: Boolean by
     option(
         names = arrayOf("--generate-kdoc"),
-        help = "Whether to preserve Pkl doc comments by generating corresponding KDoc comments."
+        help = "Whether to preserve Pkl doc comments by generating corresponding KDoc comments.",
       )
       .flag()
 
   private val generateSpringboot: Boolean by
     option(
         names = arrayOf("--generate-spring-boot"),
-        help = "Whether to generate config classes for use with Spring Boot."
+        help = "Whether to generate config classes for use with Spring Boot.",
       )
       .flag()
 
   private val implementSerializable: Boolean by
     option(
         names = arrayOf("--implement-serializable"),
-        help = "Whether to generate classes that implement java.io.Serializable."
+        help = "Whether to generate classes that implement java.io.Serializable.",
       )
       .flag()
 
@@ -91,7 +91,7 @@ class PklKotlinCodegenCommand :
             With this option, you can override or modify the default names, renaming entire
             classes or just their packages.
           """
-            .trimIndent()
+            .trimIndent(),
       )
       .associate()
 
@@ -104,7 +104,7 @@ class PklKotlinCodegenCommand :
         generateKdoc = generateKdoc,
         generateSpringBootConfig = generateSpringboot,
         implementSerializable = implementSerializable,
-        renames = renames
+        renames = renames,
       )
     CliKotlinCodeGenerator(options).run()
   }

pkl-doc/src/main/kotlin/org/pkl/doc/Main.kt

@@ -34,10 +34,10 @@ import org.pkl.core.Release
 
 /** Main method for the Pkldoc CLI. */
 internal fun main(args: Array<String>) {
-  cliMain { DocCommand().main(args) }
+  cliMain { DocCommand.main(args) }
 }
 
-class DocCommand :
+object DocCommand :
   BaseCommand(name = "pkldoc", helpLink = Release.current().documentation().homepage()) {
 
   private val modules: List<URI> by

pkl-doc/src/test/kotlin/org/pkl/doc/CliMainTest.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,12 +21,9 @@ import org.junit.jupiter.api.assertThrows
 import org.pkl.commons.cli.CliException
 
 class CliMainTest {
-
-  private val docCommand = DocCommand()
-
   @Test
   fun `CLI run test`() {
-    val e = assertThrows<CliException> { docCommand.parse(arrayOf("foo", "--output-dir", "/tmp")) }
+    val e = assertThrows<CliException> { DocCommand.parse(arrayOf("foo", "--output-dir", "/tmp")) }
     assertThat(e)
       .hasMessageContaining("must contain at least one module named `doc-package-info.pkl`")
   }