version: Pre release version bump to v0.1.0-.1

The identify is no optional with fallback to the property key or class

.github/workflows/CreateRelease.yml

@@ -4,6 +4,7 @@ on:
     push:
         branches:
             - main
+            - 'dev/*'
         paths:
             - 'package.json'
     workflow_dispatch: # Allows manual execution of the workflow.
@@ -22,20 +23,14 @@ jobs:
               with:
                   node-version: '20.8.0'
 
-            - name: Install Dependencies
+            - name: Install dependencies, run tests and build
-              run: npm install
+              run: npm run prepare:deploy
-
-            - name: Run Tests
-              run: npm run test:verbose
-
-            - name: Build the Project
-              run: npm run build:tsc
 
             - name: Get the version
               id: get_version
               run: |
                   VERSION=$(npm run version:show | tail -n 1)
-                  echo "VERSION=$VERSION" >> $GITHUB_ENV
+                  echo "VERSION=v$VERSION" >> $GITHUB_ENV
               shell: bash
 
             - name: Get previous release tag
@@ -77,8 +72,9 @@ jobs:
                   echo "Generating release notes from ${{ env.PREVIOUS_TAG }} to HEAD..."
                   repo_url=$(git config --get remote.origin.url)
                   notes=$(git log ${{ env.PREVIOUS_TAG }}..HEAD --pretty=format:"- [\`%h\`]($repo_url/commit/%H): %s%n")
-                  echo "Release notes:"
+                  echo "See [CHANGELOG.md](./CHANGELOG.md) for more details."
                   echo "$notes"
+                  echo ""
                   echo "### Changes in this release" > release_notes.md
                   echo "$notes" >> release_notes.md
               shell: bash
@@ -90,17 +86,6 @@ jobs:
                   git config --local user.email "actions@github.com"
               shell: bash
 
-            # - name: Create temporary branch
-            #   id: create_temp_branch
-            #   if: steps.check_version.outputs.skip_release == 'false'
-            #   run: |
-            #       git checkout --orphan release/v${{ env.VERSION }}
-            #       git reset
-            #       rm -f .gitignore
-            #       git add README.md package.json LICENSE dist/ src/ tsconfig.json
-            #       git commit -m "Prepare files for release ${{ env.VERSION }}"
-            #   shell: bash
-
             - name: Create and push tag
               id: create_tag
               if: steps.check_version.outputs.skip_release == 'false'
@@ -111,6 +96,15 @@ jobs:
                   GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
               shell: bash
 
+            - name: Set Release Prerelease Flag
+              id: set_prerelease_flag
+              run: |
+                  if [[ "${{ github.ref }}" == "refs/heads/main" ]]; then
+                    echo "PRE_RELEASE=false" >> $GITHUB_ENV
+                  elif [[ "${{ github.ref }}" == refs/heads/dev/* ]]; then
+                    echo "PRE_RELEASE=true" >> $GITHUB_ENV
+                  fi
+
             - name: Release
               if: steps.check_version.outputs.skip_release == 'false'
               uses: softprops/action-gh-release@v2
@@ -118,6 +112,6 @@ jobs:
                   tag_name: ${{ env.VERSION }}
                   name: Release ${{ env.VERSION }}
                   body_path: release_notes.md
-                  prerelease: true
+                  prerelease: ${{ env.PRE_RELEASE }}
               env:
                   GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/ValidateBranchName.yml

@@ -3,7 +3,7 @@ name: Validate Branch Name on Pull Request
 on:
     pull_request:
         branches:
-            - main
+            - UNDEFINED
 
 jobs:
     validate-branch-name-on-pull-request:

CHANGELOG.md

@@ -0,0 +1,62 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+### Added
+
+- feat: Add new `IdentifierRequiredError` class for missing identifiers.
+- feat: Add the option to use the decorators without passing the identifier: In this case, the identifier will be the class name (register) or the property name (inject).
+- Add pre release building to release workflow on dev/* branches an version changes.
+
+### Deprecated
+
+
+### Removed
+
+- feat!: Disable `experimentalDecorators` and `emitDecoratorMetadata` in the `tsconfig.json` file to reflect the change to the stable decorators api.
+
+### Fixed
+
+- feat!: Update `Register`, `RegisterInstance` and `Inject` decorators to reflect the change to the stable decorators api.
+- feat!: Update `Inject` Decorator typing to reflect the correct property type.
+
+### Security
+
+
+## [0.0.14]
+
+### Added
+
+- Added **ChangeLog** file and format it according to [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
+- Added reference to **Semantic Versioning** in the changelog file. (History will be updated on time).
+- Version format is now `v0.0.0` instead of `0.0.0`. Changes to this are also reflected in the workflos.
+- Add `Identifiers` and `Jest` Sections to the `README.md` file.
+- feat: Add new Error `InitializationError` to reflect errors during initialization of a dependency.
+- feat: Add initialization error handling and refactor Inject.
+- feat: After injecting a dependency, the lazzy loading getter will be replaced with the dependency itself.
+- feat: remove the use of a private property to store the injected dependencies. Now the dependencies are stored in the property itself.
+- test: Add tests for the new features.
+
+
+### Deprecated
+
+- Deprecated the old version format `0.0.0`.
+
+### Removed
+
+
+### Fixed
+
+
+### Security
+
+
+---
+
+[unreleased]: https://github.com/PxaMMaxP/TSinjex/compare/0.0.14...HEAD
+[0.0.14]: https://github.com/PxaMMaxP/TSinjex/compare/0.0.13...v0.0.14

README.md

@@ -6,8 +6,14 @@
 
 ## Configuration
 
+### Identifiers
+
+Strings and symbols are possible for the **identifiers**.
+
 ### Jest
 
+For the use of TSinjex with Jest, the corresponding source files can be found under `./src` of the TSinjex node_module folder. To use these files, the `moduleNameMapper` must be configured in the Jest configuration file. The following example shows how to configure the Jest configuration file to use the source files of TSinjex.
+
 #### Example jest setup
 
 ```ts

package.json

@@ -1,6 +1,6 @@
 {
   "name": "ts-injex",
-  "version": "0.0.13",
+  "version": "0.1.0-.1",
   "description": "Simple boilerplate code free dependency injection system for TypeScript.",
   "type": "module",
   "main": "./dist/index.js",
@@ -22,7 +22,8 @@
     "docs:fix:coverage": "node scripts/fix-coverage-paths.cjs",
     "docs:generate:badge": "node scripts/generate-badge.cjs",
     "docs:fix:escape": "node scripts/replace-doc-escaping.cjs",
-    "version:show": "node -e \"console.log(require('./package.json').version)\""
+    "version:show": "node -e \"console.log(require('./package.json').version)\"",
+    "prepare:deploy": "npm install && npm run test:verbose && npm run build:tsc"
   },
   "repository": {
     "type": "git",

src/__tests__/Decorators.spec.ts

@@ -1,3 +1,4 @@
+/* istanbul ignore file */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 import { Inject } from 'src/decorators/Inject';
 import { DependencyResolutionError } from 'src/interfaces/Exceptions';
@@ -66,6 +67,29 @@ export function test_InjectDecorator(
             expect(instance.getDependency().value).toBe('test-value-init');
         });
 
+        it('should inject dependency and run initializer without identifier', () => {
+            container.register('MockDependencyIdentifier', {
+                value: 'test-value',
+            });
+
+            class TestClass {
+                @Inject(undefined, (x: string) => {
+                    (x as unknown as { value: string }).value =
+                        'test-value-init';
+
+                    return x;
+                })
+                MockDependencyIdentifier!: any;
+
+                public getDependency() {
+                    return this.MockDependencyIdentifier;
+                }
+            }
+
+            const instance = new TestClass();
+            expect(instance.getDependency().value).toBe('test-value-init');
+        });
+
         it('should throw an error when necessary is true and the initializer throws an error', () => {
             let _error: Error | undefined = undefined;
 
@@ -77,7 +101,7 @@ export function test_InjectDecorator(
                 class TestClass {
                     @Inject(
                         'InitThrowDependencie',
-                        () => {
+                        (): any => {
                             throw new Error('Initializer error');
                         },
                         true,
@@ -117,6 +141,130 @@ export function test_InjectDecorator(
             }
             expect(_error).toBeInstanceOf(DependencyResolutionError);
         });
+
+        it('should replace the property with the resolved dependency', () => {
+            container.register('MockDependencyIdentifier', {
+                value: 'test-value',
+            });
+
+            class TestClass {
+                @Inject('MockDependencyIdentifier')
+                private readonly _dependency!: any;
+
+                public getDependency() {
+                    return this._dependency;
+                }
+
+                public isDependencyTypeofFunction() {
+                    return typeof this._dependency === 'function';
+                }
+            }
+
+            const instance = new TestClass();
+
+            expect(instance.getDependency().value).toBe('test-value');
+
+            expect(instance.isDependencyTypeofFunction()).toBe(false);
+            expect(instance.getDependency().value).toBe('test-value');
+        });
+
+        it('should use a empty initializer when none is provided but true', () => {
+            container.register(
+                'MockDependencyIdentifier',
+                class X {
+                    public value: string = 'test-value';
+                    constructor() {}
+                },
+            );
+
+            class TestClass {
+                @Inject('MockDependencyIdentifier', true)
+                private readonly _dependency!: any;
+
+                public getDependency() {
+                    return this._dependency;
+                }
+            }
+
+            const instance = new TestClass();
+            expect(instance.getDependency().value).toBe('test-value');
+        });
+
+        it('should throw an error when the dependency has no instantiation method', () => {
+            container.register('MockDependencyIdentifier', {
+                value: 'test-value',
+            });
+
+            class TestClass {
+                @Inject('MockDependencyIdentifier', true)
+                private readonly _dependency!: any;
+
+                public getDependency() {
+                    return this._dependency;
+                }
+            }
+
+            expect(() => {
+                const instance = new TestClass();
+                instance.getDependency();
+            }).toThrow(new RegExp('No instantiation method found for.*'));
+        });
+
+        it('should not throw an error when the dependency has no instantiation method if not necessary', () => {
+            container.register('MockDependencyIdentifier', {
+                value: 'test-value',
+            });
+
+            class TestClass {
+                @Inject('MockDependencyIdentifier', true, false)
+                private readonly _dependency!: any;
+
+                public getDependency() {
+                    return this._dependency;
+                }
+            }
+
+            expect(() => {
+                const instance = new TestClass();
+                instance.getDependency();
+            }).not.toThrow(new RegExp('No instantiation method found for.*'));
+        });
+
+        it('should throw an error when the dependency cannot be resolved', () => {
+            container.register('MockDependencyIdentifier', null);
+
+            class TestClass {
+                @Inject('MockDependencyIdentifier', true)
+                private readonly _dependency!: any;
+
+                public getDependency() {
+                    return this._dependency;
+                }
+            }
+
+            expect(() => {
+                const instance = new TestClass();
+                instance.getDependency();
+            }).toThrow(new RegExp('.*could not be resolved.*'));
+        });
+
+        it('should not throw an error when the dependency cannot be resolved if not necessary', () => {
+            container.register('MockDependencyIdentifier', null);
+
+            class TestClass {
+                @Inject('MockDependencyIdentifier', true, false)
+                private readonly _dependency!: any;
+
+                public getDependency() {
+                    return this._dependency;
+                }
+            }
+
+            expect(() => {
+                const instance = new TestClass();
+                instance.getDependency();
+            }).not.toThrow(new RegExp('.*could not be resolved.*'));
+        });
     });
 }
 
@@ -150,6 +298,19 @@ export function test_RegisterDecorator(
                 TestClass,
             );
         });
+
+        it('should register a dependency without an identifier', () => {
+            @register()
+            class TestClass {
+                private readonly _dependency!: any;
+
+                public getDependency() {
+                    return this._dependency;
+                }
+            }
+
+            expect(container.resolve('TestClass')).toBe(TestClass);
+        });
     });
 }
 
@@ -186,6 +347,23 @@ export function test_RegisterInstanceDecorator(
             ).toBe('instance');
         });
 
+        it('should register an instance of a dependency with an identifier', () => {
+            @registerInstance()
+            class TestClass {
+                private readonly _dependency!: any;
+
+                public getDependency() {
+                    return this._dependency;
+                }
+
+                public mark: string = 'instance';
+            }
+
+            expect(container.resolve<TestClass>('TestClass').mark).toBe(
+                'instance',
+            );
+        });
+
         it('should register an instance of a dependency an run the init function', () => {
             @registerInstance(
                 'InstanceIdentifier',

src/__tests__/Functions.spec.ts

@@ -1,3 +1,4 @@
+/* istanbul ignore file */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 import { ITSinjex, ITSinjex_ } from 'src/interfaces/ITSinjex';
 

src/__tests__/ITSinjex.spec.ts

@@ -1,3 +1,4 @@
+/* istanbul ignore file */
 import { ITSinjex_, ITSinjex } from '../interfaces/ITSinjex';
 
 /**

src/classes/TSinjex.ts

@@ -114,7 +114,7 @@ export class TSinjex implements ITSinjex {
         }
 
         if (dependency.deprecated) {
-            console.warn(`Dependency ${identifier} is deprecated`);
+            console.warn(`Dependency ${identifier.toString()} is deprecated`);
 
             // Remove the deprecation warning; it should only be logged once.
             dependency.deprecated = false;

src/decorators/Inject.ts

@@ -1,19 +1,31 @@
+import {
+    DependencyResolutionError,
+    IdentifierRequiredError,
+    InitializationError,
+    InjectorError,
+    NoInstantiationMethodError,
+} from 'src/interfaces/Exceptions';
 import { TSinjex } from '../classes/TSinjex';
 import { Identifier } from '../types/Identifier';
 import { InitDelegate } from '../types/InitDelegate';
 
 /**
  * A decorator to inject a dependency from a DI (Dependency Injection) container into a class property.
- * @template T The type of the dependency to be injected.
+ * @template TargetType The type of the class to inject the dependency into.
- * @template U The type of the property to be injected.
+ * @template DependencyType The type of the dependency to be injected.
- * @param identifier The identifier used to resolve the class in the DI container.
+ * @template PropertyType The type of the property to be injected.
- * @see {@link Identifier} for more information on identifiers.
+ * @param identifier The {@link Identifier|identifier} used to resolve the dependencie in the DI container or the property name if not provided.
- * @param init An optional initializer function to transform the dependency before injection.
+ * @param init An optional initializer {@link InitDelegate|function} to transform the dependency before injection
- * @see {@link InitDelegate} for more information on initializer functions.
+ * or true to instantiate the dependency if it has a constructor.
  * @param necessary If true, throws an error if the dependency is not found.
  * @returns The resolved dependency or undefined if the dependency is not necessary
  * and not found, or throws an error if the dependency is necessary and not found.
- * @throws A {@link DependencyResolutionError} if the dependency is not found and necessary.
+ * @throws **Only throws errors if the dependency is necessary.**
+ * @throws An {@link IdentifierRequiredError} if the identifier is not provided and the class name is not available.
+ * @throws A {@link DependencyResolutionError} if the dependency is not found.
+ * @throws A {@link InjectorError} if an error occurs during the injection process.
+ * @throws A {@link NoInstantiationMethodError} if the dependency does not have a constructor.
+ * @throws An {@link InitializationError} if an error occurs during the initialization process.
  * @example
  * ```ts
  * class MyClass {
@@ -29,49 +41,128 @@ import { InitDelegate } from '../types/InitDelegate';
  * }
  * ```
  */
-export function Inject<T, U>(
+export function Inject<TargetType, DependencyType, PropertyType>(
-    identifier: Identifier,
+    identifier?: Identifier,
-    init?: InitDelegate<T, U>,
+    init?: InitDelegate<DependencyType, PropertyType> | true,
     necessary = true,
 ) {
-    return function (target: unknown, propertyKey: string | symbol): void {
+    return function (
-        // Unique symbol to store the private property
+        constructor: undefined,
-        const privatePropertyKey: unique symbol = Symbol();
+        context: ClassFieldDecoratorContext<TargetType> & {
-        // Get the DI container instance
+            name: PropertyType;
-        const diContainer = TSinjex.getInstance();
+        },
+    ): void {
+        const _identifier = identifier ?? context.name;
 
-        // Function to evaluate the dependency lazily
+        if (_identifier == null && necessary === true)
-        // to avoid circular dependencies, not found dependencies, etc.
+            throw new IdentifierRequiredError();
-        const evaluate = (): T | undefined => {
+
-            return diContainer.resolve<T>(identifier, necessary);
+        /**
+         * Function to evaluate the dependency lazily
+         * to avoid circular dependencies, not found dependencies, etc.
+         * @returns The resolved dependency or undefined if the dependency is not found.
+         */
+        const resolve = (): DependencyType | undefined => {
+            return TSinjex.getInstance().resolve<DependencyType>(
+                _identifier,
+                necessary,
+            );
         };
 
-        // Define the property
+        context.addInitializer(function (this: TargetType) {
-        Object.defineProperty(target, propertyKey, {
+            Object.defineProperty(this, context.name, {
-            get() {
+                get() {
-                // If the property is not defined, evaluate the dependency
+                    let instance: DependencyType | PropertyType | undefined;
-                if (!this.hasOwnProperty(privatePropertyKey)) {
-                    if (init) {
-                        try {
-                            this[privatePropertyKey] = init(evaluate() as T);
-                        } catch (error) {
-                            if (necessary) {
-                                throw error;
-                            }
-                        }
-                    } else {
-                        this[privatePropertyKey] = evaluate();
-                    }
-                }
 
-                return this[privatePropertyKey];
+                    const dependency: DependencyType | undefined = tryAndCatch(
-            },
+                        () => resolve(),
-            // Not necessary to set the property
+                        necessary,
-            // set(value: PropertieType) {
+                        _identifier,
-            //     this[privatePropertyKey] = value;
+                        DependencyResolutionError,
-            // },
+                    );
-            enumerable: true,
+
-            configurable: false,
+                    if (dependency != null) {
+                        const initFunction: (() => PropertyType) | undefined =
+                            typeof init === 'function' && dependency != null
+                                ? (): PropertyType => init(dependency)
+                                : init === true && hasConstructor(dependency)
+                                  ? (): PropertyType =>
+                                        new dependency() as PropertyType
+                                  : undefined;
+
+                        if (init == null) instance = dependency;
+                        else if (initFunction != null)
+                            instance = tryAndCatch(
+                                initFunction,
+                                necessary,
+                                _identifier,
+                                InitializationError,
+                            );
+                        else if (necessary)
+                            throw new NoInstantiationMethodError(_identifier);
+                    } else if (necessary)
+                        throw new DependencyResolutionError(_identifier);
+
+                    /**
+                     * Replace itself with the resolved dependency
+                     * for performance reasons.
+                     */
+                    Object.defineProperty(this, context.name, {
+                        value: instance,
+                        writable: false,
+                        enumerable: false,
+                        configurable: false,
+                    });
+
+                    return instance;
+                },
+                /**
+                 * Make the property configurable to allow replacing it
+                 */
+                configurable: true,
+            });
         });
     };
 }
+
+/**
+ * Tries to execute a function and catches any errors that occur.
+ * If the function is necessary and an error occurs, it throws the error
+ * with the specified error class and identifier.
+ * @param fn The function to execute.
+ * @param necessary If true, throws an error if an error occurs.
+ * @param identifier The identifier of the dependency.
+ * @param errorClass The error class to throw if an error occurs.
+ * @returns The result of the function or undefined if an error occurs and the function is not necessary.
+ */
+function tryAndCatch<ReturnType, ErrorType>(
+    fn: () => ReturnType,
+    necessary: boolean,
+    identifier?: Identifier,
+    errorClass?: ErrorType,
+): ReturnType | undefined {
+    try {
+        return fn();
+    } catch (error) {
+        if (necessary)
+            throw new (errorClass != null ? errorClass : error)(
+                identifier ?? 'not specified',
+                error,
+            );
+        else return undefined;
+    }
+}
+
+/**
+ * Checks if an object has a constructor.
+ * @param obj The object to check.
+ * @returns True if the object has a constructor, false otherwise.
+ */
+function hasConstructor<T>(obj: T): obj is T & { new (): unknown } {
+    const _obj = obj as unknown as { prototype?: { constructor?: unknown } };
+
+    return (
+        _obj?.prototype != null &&
+        typeof _obj.prototype.constructor === 'function'
+    );
+}

src/decorators/Register.ts

@@ -1,14 +1,14 @@
+import { IdentifierRequiredError } from 'src/interfaces/Exceptions';
 import { TSinjex } from '../classes/TSinjex';
 import { Identifier } from '../types/Identifier';
 
 /**
  * A decorator to register a class in the **TSinjex** DI (Dependency Injection) container.
  * @template TargetType The type of the class to be registered.
- * @param identifier The identifier used to register the class in the DI container.
+ * @param identifier The {@link Identifier|identifier} used to register the class in the DI container or the class name if not provided.
- * @see {@link Identifier} for more information on identifiers.
+ * @param deprecated If true, the dependency is deprecated and a warning is logged only once upon the first resolution of the dependency.
- * @param deprecated If true, the dependency is deprecated and a warning
- * is logged only once upon the first resolution of the dependency.
  * @returns The decorator function to be applied on the class.
+ * @throws An {@link IdentifierRequiredError} if the identifier is not provided and the class name is not available.
  * @example
  * ```ts
  * \@Register('MyClassIdentifier')
@@ -19,12 +19,16 @@ import { Identifier } from '../types/Identifier';
  */
 export function Register<
     TargetType extends new (...args: unknown[]) => InstanceType<TargetType>,
->(identifier: Identifier, deprecated?: boolean) {
+>(identifier?: Identifier, deprecated?: boolean) {
-    return function (constructor: TargetType, ...args: unknown[]): void {
+    return function (
-        // Get the instance of the DI container
+        constructor: TargetType,
-        const diContainer = TSinjex.getInstance();
+        context: ClassDecoratorContext<TargetType>,
+    ) {
+        const _identifier = identifier ?? context.name;
 
-        // Register the class in the DI container
+        if (_identifier == null) throw new IdentifierRequiredError();
-        diContainer.register(identifier, constructor, deprecated);
+
+        const diContainer = TSinjex.getInstance();
+        diContainer.register(_identifier, constructor, deprecated);
     };
 }

src/decorators/RegisterInstance.ts

@@ -1,3 +1,4 @@
+import { IdentifierRequiredError } from 'src/interfaces/Exceptions';
 import { TSinjex } from '../classes/TSinjex';
 import { Identifier } from '../types/Identifier';
 import { InitDelegate } from '../types/InitDelegate';
@@ -5,12 +6,11 @@ import { InitDelegate } from '../types/InitDelegate';
 /**
  * A decorator to register an instance of a class in the DI (Dependency Injection) container.
  * @template TargetType The type of the class whose instance is to be registered.
- * @param identifier The identifier used to register the instance in the DI container.
+ * @param identifier The {@link Identifier|identifier} used to register the class in the DI container or the class name if not provided.
- * @see {@link Identifier} for more information on identifiers.
+ * @param init An optional initializer {@link InitDelegate|function} which get the constructor of the class
- * @param init An optional initializer function which get the constructor of the class
  * as input and returns an instance of the class.
- * @see {@link InitDelegate} for more information on initializer functions.
  * @returns The decorator function to be applied on the class.
+ * @throws An {@link IdentifierRequiredError} if the identifier is not provided and the class name is not available.
  * @example
  * ```ts
  * \@RegisterInstance('MyClassInstanceIdentifier', (constructor) => new constructor())
@@ -22,43 +22,51 @@ import { InitDelegate } from '../types/InitDelegate';
 export function RegisterInstance<
     TargetType extends new (..._args: unknown[]) => InstanceType<TargetType>,
 >(
-    identifier: Identifier,
+    identifier?: Identifier,
     init?: InitDelegate<
         TargetType & { new (..._args: unknown[]): InstanceType<TargetType> },
         InstanceType<TargetType>
     >,
 ) {
-    return function (constructor: TargetType, ...args: unknown[]): void {
+    return function (
-        // Get the instance of the DI container
+        constructor: TargetType,
+        context: ClassDecoratorContext<TargetType>,
+    ): void {
+        const _identifier = identifier ?? context.name;
+
+        if (_identifier == null) throw new IdentifierRequiredError();
+
         const diContainer = TSinjex.getInstance();
         let instance: InstanceType<TargetType>;
 
+        /**
+         * Get the instance of the class
+         * and replace the lazy proxy with the instance
+         * for performance optimization.
+         */
+        const getAndRegisterInstance = (): void => {
+            if (instance == null) {
+                if (init) {
+                    instance = init(constructor);
+                } else {
+                    instance = new constructor();
+                }
+            }
+            diContainer.register(_identifier, instance);
+        };
+
         // Create a proxy to instantiate the class when needed (Lazy Initialization)
-        let lazyProxy: unknown = new Proxy(
+        const lazyProxy: unknown = new Proxy(
             {},
             {
-                get(target, prop, receiver) {
+                get(_target, prop, _receiver) {
-                    if (instance == null) {
+                    getAndRegisterInstance();
-                        if (init) {
-                            instance = init(constructor);
-                        } else {
-                            instance = new constructor(...args);
-                        }
-                    }
-                    lazyProxy = instance;
 
                     // Return the requested property of the instance
                     return instance[prop as keyof InstanceType<TargetType>];
                 },
-                set(target, prop, value, receiver) {
+                set(_target, prop, value, _receiver) {
-                    if (instance == null) {
+                    getAndRegisterInstance();
-                        if (init) {
-                            instance = init(constructor);
-                        } else {
-                            instance = new constructor(...args);
-                        }
-                    }
-                    lazyProxy = instance;
 
                     // Set the requested property of the instance
                     return (instance[prop as keyof InstanceType<TargetType>] =
@@ -67,7 +75,6 @@ export function RegisterInstance<
             },
         );
 
-        // Register the lazy proxy in the DI container
+        diContainer.register(_identifier, lazyProxy);
-        diContainer.register(identifier, lazyProxy);
     };
 }

src/interfaces/Exceptions.ts

@@ -1,3 +1,4 @@
+import { Identifier } from 'src/types/Identifier';
 import { ITSinjex } from './ITSinjex';
 
 /**
@@ -14,6 +15,19 @@ export class TSinjexError extends Error {
     }
 }
 
+/**
+ * Error class for missing identifiers in {@link ITSinjex} methods.
+ */
+export class IdentifierRequiredError extends TSinjexError {
+    /**
+     * Creates a new instance of {@link IdentifierRequiredError}
+     */
+    constructor() {
+        super('Identifier is required.');
+        this.name = 'TSinjexIdentifierRequiredError';
+    }
+}
+
 /**
  * Error class for dependency resolution errors in {@link ITSinjex}.
  * @see {@link ITSinjex.resolve}
@@ -23,8 +37,61 @@ export class DependencyResolutionError extends TSinjexError {
      * Creates a new instance of {@link DependencyResolutionError}
      * @param identifier **The identifier of the dependency**
      */
-    constructor(identifier: string) {
+    constructor(identifier: Identifier) {
-        super(`Dependency ${identifier} could not be resolved.`);
+        super(`Dependency ${identifier.toString()} could not be resolved.`);
         this.name = 'TSinjexResolutionError';
     }
 }
+
+/**
+ * Error class for Injector errors in {@link ITSinjex}.
+ * @see {@link ITSinjex.inject}
+ */
+export class InjectorError extends TSinjexError {
+    /**
+     * Creates a new instance of {@link InjectorError}
+     * @param identifier **The identifier of the dependency**
+     * @param originalError **The original error that caused the injection error**
+     */
+    constructor(identifier: Identifier, originalError?: Error) {
+        super(
+            `Error injecting dependency ${identifier.toString()} with error: "${originalError}"`,
+        );
+        this.name = 'TSinjexInjectorError';
+    }
+}
+
+/**
+ * Error class for missing instantiation methods in {@link ITSinjex}.
+ * @see {@link ITSinjex.inject}
+ */
+export class NoInstantiationMethodError extends TSinjexError {
+    /**
+     * Creates a new instance of {@link NoInstantiationMethodError}
+     * @param identifier **The identifier of the dependency**
+     */
+    constructor(identifier: Identifier) {
+        super(
+            `No instantiation method found for dependency ${identifier.toString()}.`,
+        );
+        this.name = 'TSinjexNoInstantiationMethodError';
+    }
+}
+
+/**
+ * Error class for errors during the initialization of a dependency in {@link ITSinjex}.
+ * @see {@link ITSinjex.inject}
+ */
+export class InitializationError extends TSinjexError {
+    /**
+     * Creates a new instance of {@link InitializationError}
+     * @param identifier **The identifier of the dependency**
+     * @param originalError **The original error that caused the initialization error**
+     */
+    constructor(identifier: Identifier, originalError?: Error) {
+        super(
+            `Error initializing dependency ${identifier.toString()} with error: "${originalError}"`,
+        );
+        this.name = 'TSinjexInitializationError';
+    }
+}

src/types/Identifier.ts

@@ -8,4 +8,4 @@
  * I.e. a class `ClassA` that implements the interface `IClassA` and is
  * registered as a dependent class is registered under the interface name `IClassA`.
  */
-export type Identifier = string;
+export type Identifier = string | symbol;

tsconfig.json

@@ -18,8 +18,6 @@
         "importHelpers": true,
         "isolatedModules": true,
         "resolveJsonModule": true,
-        "experimentalDecorators": true,
-        "emitDecoratorMetadata": true,
         "strictNullChecks": true,
         "strictPropertyInitialization": true,
         "lib": [