Entry point
An entry point is a designated starting location or interface through which a program, component, process, or interaction begins.
The Art of Unit Testing 3e
An externally triggerable function or interface through which execution of a unit of work begins.
- How it is used
- Frames unit tests as invoking useful work through a public doorway and checking an externally visible result.
- How deep it goes
- Defines entry points and traces them through multi-module work, then details an async extraction refactoring pattern.
- Examples
- Uses sum with running state and logging, Password Verifier logging, and extracted fetch success and error handlers.
- What you can do after
- Apply it by selecting public triggers for focused tests and extracting async result logic into directly callable functions.
Learn Go with Pocket-Sized Projects
The main function is the parameterless Go entry-point function executed when a program runs.
- How it is used
- Starts executable Go programs, including small applications, command-line tools, and HTTP servers.
- How deep it goes
- Explains the required package and function shape, then demonstrates CLI handling and HTTP server startup without deeper runtime internals.
- Examples
- Uses a Hello World program, an empty project scaffold, a money-converter CLI, and an HTTP server.
- What you can do after
- Build a runnable Go executable and organize its startup logic for a CLI or HTTP server.
Read how Learn Go with Pocket-Sized Projects explains entry point →
Modern C
An entry point is a program location at which execution of a function or other callable unit begins.
- How it is used
- Marks where program or function execution begins, especially at main’s boundary between the runtime system and application.
- How deep it goes
- Explains standard main prototypes, termination status, exit behavior, and assembler labels, but stops short of runtime startup internals.
- Examples
- Uses the two standard main prototypes, EXIT_SUCCESS and EXIT_FAILURE, exit, and the fgoto assembler label.
- What you can do after
- Evaluate/understand which C main forms are portable and how assembler labels identify function entry locations.
Go in Action, Second Edition
The main function is the specially named Go function that serves as the starting point of an executable program.
- How it is used
- Locates executable startup in main() within package main, including executables organized as separate tools or services.
- How deep it goes
- Explains compiler discovery and program lifetime, but defers robust goroutine synchronization.
- Examples
- Uses an RSS-feed fetch, a prematurely exiting goroutine, and a cmd/myapp/main.go layout.
- What you can do after
- Build it from scratch as a Go executable with package main and main(), while accounting for background work before main() returns.
Read how Go in Action, Second Edition explains entry point →
.NET MAUI in Action
An entry point is the method or platform-specific component at which an application begins execution.
- How it is used
- Starts a .NET MAUI application and leads execution to its initial page.
- How deep it goes
- Distinguishes Main from CreateMauiApp and traces host construction, application creation, and initial page assignment.
- Examples
- Uses MauiProgram.cs, App.xaml.cs, CreateMauiApp, UseMauiApp<App>(), and new MainPage() as concrete artifacts.
- What you can do after
- Build it from scratch by configuring MauiProgram and assigning an initial Page through the App class.
Clojure: The Essential Reference
A main method is a Java entry-point method that Java launchers invoke to start an application.
- How it is used
- Bootstraps and executes Clojure applications by parsing command-line parameters and selecting a program or the default REPL.
- How deep it goes
- Defines main’s startup role and briefly describes load-script and repl, without detailing launcher invocation.
- Examples
- Demonstrates script loading and customized calculator REPLs with initialization, prompts, input parsing, and evaluation.
- What you can do after
- Operate/configure Clojure startup by loading scripts or launching a customized REPL through clojure.main.
Read how Clojure: The Essential Reference explains entry point →
The Quick Python Book, Fourth Edition
A main function, or controlling function, is a conventionally designated function that coordinates a program's execution and serves as its controlling entry point.
- How it is used
- Coordinates a Python script's execution while separating scripting plumbing from reusable functions and modules.
- How deep it goes
- Explains definition, invocation, placement, and the import-safe name guard without descending into runtime implementation details.
- Examples
- Uses a minimal main script, a number-to-words command-line program, an import-safe module, and a package refactoring exercise.
- What you can do after
- Build it from scratch by defining a main function, invoking it, and guarding the call for safe importing.
Read how The Quick Python Book, Fourth Edition explains entry point →
Pro Angular 16
An entry point is the initial source module from which a build tool discovers an application's dependency graph.
- How it is used
- Starts webpack's dependency discovery and Angular's browser initialization from src/main.ts.
- How deep it goes
- Explains dependency traversal, bundle naming, and bootstrap calls, but does not detail webpack configuration internals.
- Examples
- Uses src/main.ts, AppModule, main.js, and incremental ng serve rebuilds as concrete examples.
- What you can do after
- Evaluate/understand how a source module drives Angular startup, dependency compilation, bundle creation, and incremental rebuilding.
Learn Rust in a Month of Lunches
The main function is the entry-point function that Rust starts when running an executable program.
- How it is used
- Starts an executable Rust program and provides the first code block to run.
- How deep it goes
- Defines main, empty arguments, and its code block, but stops short of runtime startup internals.
- Examples
- Uses a minimal Hello, world! program to show main executing println!.
- What you can do after
- Understand where a Rust executable begins and place its initial statements inside main.
Read how Learn Rust in a Month of Lunches explains entry point →
Get Programming with JavaScript Next: New features of ECMAScript 2015, 2016, and beyond
The initial file or module from which dependency analysis and loading begins in a module graph.
- How it is used
- Starts Browserify’s dependency analysis from the main JavaScript file.
- How deep it goes
- Defines the starting file and traces imported scripts into a dependency tree, stopping at the bundling workflow.
- Examples
- Follows a main JavaScript file and its imported scripts into a single browser-ready bundle.
- What you can do after
- Apply Browserify to bundle a main file and its required modules for a webpage.
Related concepts
- database transactionpart of · A database transaction is a logical unit of database operations whose changes are committed together or rolled back as a whole.
- functionkind of · A function is a callable program unit that performs an operation, may accept inputs, and can produce a result or side effect.
- moduleuses · A module is a distinct, bounded software unit that groups related code or functionality and provides an organizational or interaction boundary within a larger system.
- exitequivalent to · exit is a standard-library function that terminates normal program execution after performing required termination processing, without ordinarily unwinding active automatic objects.
- printfuses · printf is a formatted-output API that uses a format specification and supplied values to produce text, either returning it or writing it to an output destination.
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