Use definite assignment for required fields in docs and examples

Author: sigmaSd

README.md

@@ -23,12 +23,12 @@ class Calculator extends Args {
   @argument({ description: "first number" })
   @type("number")
   @required()
-  a?: number;
+  a!: number;
 
   @argument({ description: "second number" })
   @type("number")
   @required()
-  b?: number;
+  b!: number;
 
   @description("operation to perform")
   operation = "add";
@@ -37,12 +37,8 @@ class Calculator extends Args {
 // Parse command line arguments
 const args = Calculator.parse(["10", "5"]);
 
-// Handle potentially undefined values
-if (args.a !== undefined && args.b !== undefined) {
-  console.log(`${args.a} ${args.operation} ${args.b} = ${args.a + args.b}`);
-} else {
-  console.error("Both numbers are required");
-}
+// Use the required values directly
+console.log(`${args.a} ${args.operation} ${args.b} = ${args.a + args.b}`);
 ```
 
 Usage:
@@ -137,7 +133,7 @@ if (args.serve) {
 ```typescript ignore
 @type("string")
 @required()
-apiKey?: string;
+apiKey!: string;
 ```
 
 **Optional properties** (with default values):
@@ -164,7 +160,7 @@ apiKey?: string;
 // ✅ Fixed - add @type decorator
 @type("string")
 @required()
-apiKey?: string;
+apiKey!: string;
 
 // ✅ Or provide a default (no @type needed)
 apiKey = "";
@@ -193,13 +189,13 @@ class DeployCommand extends Args {
   @argument({ description: "Application name to deploy" })
   @type("string")
   @required()
-  appName?: string;
+  appName!: string;
 
   @argument({ description: "Target environment" })
   @type("string")
   @addValidator(oneOf(["dev", "staging", "prod"]))
   @required()
-  environment?: string;
+  environment!: string;
 
   @argument({ description: "Version to deploy (optional)" })
   @type("string")
@@ -218,33 +214,28 @@ class DeployCommand extends Args {
   @description("API key for authentication")
   @type("string")
   @required()
-  apiKey?: string;
+  apiKey!: string;
 }
 
 // Parse arguments
 const args = DeployCommand.parse(["myapp", "prod", "--apiKey", "secret123"]);
 
-// Type-safe usage with proper undefined checking
-if (args.appName && args.environment && args.apiKey) {
-  console.log(`Deploying ${args.appName} to ${args.environment}`);
-
-  if (args.version) {
-    console.log(`Version: ${args.version}`);
-  } else {
-    console.log("Version: latest");
-  }
-
-  if (args.verbose) {
-    console.log(`Instances: ${args.instances}`);
-    console.log(`Force mode: ${args.force}`);
-    console.log(`API Key: ${args.apiKey.substring(0, 4)}...`);
-  }
+// Type-safe usage - required fields are guaranteed
+console.log(`Deploying ${args.appName} to ${args.environment}`);
 
-  // Proceed with deployment...
+if (args.version) {
+  console.log(`Version: ${args.version}`);
 } else {
-  console.error("Missing required arguments");
-  Deno.exit(1);
+  console.log("Version: latest");
+}
+
+if (args.verbose) {
+  console.log(`Instances: ${args.instances}`);
+  console.log(`Force mode: ${args.force}`);
+  console.log(`API Key: ${args.apiKey.substring(0, 4)}...`);
 }
+
+// Proceed with deployment...
 ```
 
 Usage examples:
@@ -294,16 +285,12 @@ class Server extends Args {
   @description("API key for authentication")
   @type("string")
   @required()
-  apiKey?: string;
+  apiKey!: string;
 }
 
 const config = Server.parse(["--apiKey", "secret123"]);
-if (config.apiKey) {
-  console.log(`Starting server on ${config.host}:${config.port}`);
-  console.log(`API Key: ${config.apiKey.substring(0, 4)}...`);
-} else {
-  console.error("API key is required");
-}
+console.log(`Starting server on ${config.host}:${config.port}`);
+console.log(`API Key: ${config.apiKey.substring(0, 4)}...`);
 ```
 
 ### Application with Subcommands
@@ -391,7 +378,7 @@ class FileProcessor extends Args {
   @argument({ description: "Input file to process" })
   @type("string")
   @required()
-  input?: string;
+  input!: string;
 
   @argument({ description: "Output file" })
   @type("string")
@@ -415,13 +402,11 @@ const args = FileProcessor.parse([
   "transform",
 ]);
 
-// Handle potentially undefined values
-if (args.input) {
-  console.log(`Processing ${args.input} -> ${args.output || "stdout"}`);
-  console.log(`Mode: ${args.mode}`);
-  if (args.extras && args.extras.length > 0) {
-    console.log(`Extras: ${args.extras.join(", ")}`);
-  }
+// Required field is guaranteed to be present
+console.log(`Processing ${args.input} -> ${args.output || "stdout"}`);
+console.log(`Mode: ${args.mode}`);
+if (args.extras && args.extras.length > 0) {
+  console.log(`Extras: ${args.extras.join(", ")}`);
 }
 ```
 
@@ -525,7 +510,7 @@ class User extends Args {
   @type("string")
   @required()
   @email()
-  email?: string;
+  email!: string;
 }
 ```
 

examples/cli_api_example.ts

@@ -25,12 +25,12 @@ class Calculator extends Args {
   @description("First number to operate on")
   @type("number")
   @required()
-  a?: number;
+  a!: number;
 
   @description("Second number to operate on")
   @type("number")
   @required()
-  b?: number;
+  b!: number;
 
   @description("Operation to perform")
   @addValidator(oneOf(["add", "subtract", "multiply", "divide"]))

examples/error-handling.ts

@@ -117,7 +117,7 @@ class StartCommand {
   @required()
   @type("string")
   @description("Configuration file path")
-  config: string = "";
+  config!: string;
 }
 
 @command
@@ -303,7 +303,7 @@ class ConfigManager {
         @description("Database URL")
         @required()
         @type("string")
-        dbUrl: string = "";
+        dbUrl!: string;
 
         @description("API port")
         port: number = 3000;

examples/example.ts

@@ -69,11 +69,11 @@ class ServeCommand {
 class BuildCommand {
   @description("Output directory")
   @required()
-  output: string = "";
+  output!: string;
 
   @description("Source files to build")
   @required()
-  sources: string[] = [];
+  sources!: string[];
 
   @description("Enable minification")
   minify: boolean = false;
@@ -108,7 +108,7 @@ class ProcessCommand {
   @argument({ description: "Input file to process" })
   @required()
   @type("string")
-  input: string = "";
+  input!: string;
 
   @argument({ description: "Output file path" })
   @type("string")

mod.ts

@@ -12,21 +12,19 @@
  *   @description("First number")
  *   @type("number")
  *   @required()
- *   a?: number;
+ *   a!: number;
  *
  *   @description("Second number")
  *   @type("number")
  *   @required()
- *   b?: number;
+ *   b!: number;
  *
  *   @description("Operation to perform")
  *   operation = "add";
  * }
  *
  * const args = Calculator.parse(["--a", "10", "--b", "5"]);
- * if (args.a !== undefined && args.b !== undefined) {
- *   console.log(`${args.a} ${args.operation} ${args.b} = ${args.a + args.b}`);
- * }
+ * console.log(`${args.a} ${args.operation} ${args.b} = ${args.a + args.b}`);
  * ```
  *
  * @example With subcommands

src/decorators.ts

@@ -57,7 +57,7 @@ export interface DecoratorContext {
  *   // Explicit type for property without default
  *   @type("number")
  *   @required()
- *   timeout?: number;
+ *   timeout!: number;
  *
  *   // Override default-inferred type
  *   @type("string[]")
@@ -116,7 +116,7 @@ export function type(
  *   @argument({ description: "Input file to process" })
  *   @type("string")
  *   @required()
- *   input?: string;
+ *   input!: string;
  * }
  * ```
  */
@@ -233,7 +233,7 @@ export function addValidator(validator: Validator): (
  *   // Required with explicit type
  *   @type("string")
  *   @required()
- *   apiKey?: string;
+ *   apiKey!: string;
  *
  *   // Required with default (makes the default required if not overridden)
  *   @required()
@@ -281,7 +281,7 @@ export function required(): (
  *   @validate((value: string) => value.length >= 8, "must be at least 8 characters")
  *   @type("string")
  *   @required()
- *   password?: string;
+ *   password!: string;
  * }
  * ```
  */
@@ -483,7 +483,7 @@ export function subCommand<T extends new () => unknown>(
  *   @argument({ description: "Input file to process" })
  *   @type("string")
  *   @required()
- *   input?: string;
+ *   input!: string;
  *
  *   // Optional second argument
  *   @argument({ description: "Output file" })
@@ -565,7 +565,7 @@ export function argument(
  *   @argument({ description: "Binary name to execute" })
  *   @type("string")
  *   @required()
- *   binary?: string;
+ *   binary!: string;
  *
  *   @rawRest("Arguments to pass to the binary")
  *   @type("string[]")

src/metadata.ts

@@ -76,7 +76,7 @@ function isUserDefinedProperty(descriptor: PropertyDescriptor): boolean {
  *   @argument({ description: "Input file" })
  *   @type("string")
  *   @required()
- *   input?: string;
+ *   input!: string;
  *
  *   @argument({ description: "Output file" })
  *   @type("string")
@@ -264,7 +264,7 @@ function validatePositionalArguments(
  *   // From explicit @type() decorator
  *   @type("number")
  *   @required()
- *   timeout?: number; // → "number"
+ *   timeout!: number; // → "number"
  *
  *   // From default value
  *   port = 3000; // → "number"

src/validation.ts

@@ -65,7 +65,7 @@ export function validateValue(
  *   @type("string")
  *   @addValidator(requiredValidator())
  *   @required()
- *   name?: string;
+ *   name!: string;
  * }
  * ```
  */

tests/cli_api.test.ts

@@ -94,7 +94,7 @@ Deno.test("Args API - required fields", () => {
     @description("Required API key")
     @type("string")
     @required()
-    apiKey: string = "";
+    apiKey!: string;
 
     @description("Optional debug flag")
     debug: boolean = false;