⚡ cli-fp: Native CLIs for Free Pascal

• Start smallBuild one useful root command with the class-based API.
• Grow cleanlyAdd named and nested commands when the CLI needs them.
• Stay consistentShare validation, help, completion and terminal output.
• Generate when usefulUse cli-fp-gen for larger command trees, not for your first step.

cli-fp is a small Free Pascal framework for native command-line programs. It provides command trees, validated options, generated help and shell completion, colours, spinners, and progress bars—without third-party runtime dependencies.

Prerequisites

• Install Free Pascal; FPC 3.2.2 is the tested repository version. Check it with fpc -iV.
• Put the fpc executable on your PATH so the compiler command works from a terminal.
• Lazarus is optional. It can use the supplied package at packages/lazarus/cli_fp.lpk.

If you start in an empty folder, copy the QuickStartDemo source and compile it with a unit search path pointing at the cloned library:

fpc -Fu/path/to/cli-fp/src QuickStartDemo.lpr

-Fu means “add this directory to FPC's unit search path.” If compilation reports Fatal: Can't find unit CLI.Interfaces, the path is missing or points to the wrong checkout. In Lazarus, install/open packages/lazarus/cli_fp.lpk to provide the same unit path through the IDE.

Your first CLI

This complete root-command program is also QuickStartDemo, compiled by the Windows and Linux example smoke checks.

program QuickStartDemo;

{$mode objfpc}{$H+}{$J-}

uses
  CLI.Interfaces, CLI.Application, CLI.Command;

type
  THelloCommand = class(TBaseCommand)
  public
    function Execute: Integer; override;
  end;

function THelloCommand.Execute: Integer;
var
  PersonName: string;
begin
  if not GetParameterValue('--name', PersonName) then
    PersonName := 'World';
  WriteLn('Hello, ', PersonName, '!');
  Result := 0;
end;

var
  App: ICLIApplication;
  Main: THelloCommand;
begin
  Main := THelloCommand.Create('', 'Print a greeting');
  Main.AddStringParameter('-n', '--name', 'Name to greet', False, 'World');
  App := CreateCLIApplication('hello', '1.0.0', Main);
  Halt(App.Execute);
end.

Clone the repository, enter it, then build and run (Bash):

git clone https://github.com/ikelaiah/cli-fp.git
cd cli-fp
fpc -Fu./src ./examples/QuickStartDemo/QuickStartDemo.lpr
./examples/QuickStartDemo/QuickStartDemo --name Ada

$ ./examples/QuickStartDemo/QuickStartDemo --name Ada
Hello, Ada!

PowerShell equivalent:

git clone https://github.com/ikelaiah/cli-fp.git
Set-Location cli-fp
fpc "-Fu.\src" .\examples\QuickStartDemo\QuickStartDemo.lpr
.\examples\QuickStartDemo\QuickStartDemo.exe --name Ada

The empty name in THelloCommand.Create('', ...) marks the root/default command, so no command name is needed before --name. CreateCLIApplication('hello', ...) sets display metadata; it does not rename the binary. FPC builds QuickStartDemo (Windows: QuickStartDemo.exe). The factory constructs the application; App.Execute parses and validates arguments, handles built-ins, and dispatches the selected command. Keep the command and application references and let the ICLIApplication own the registered command tree; do not manually free registered commands. Halt(App.Execute) is the beginner-recommended program tail.

Quick self-checks are:

./examples/QuickStartDemo/QuickStartDemo --help
./examples/QuickStartDemo/QuickStartDemo --version
./examples/QuickStartDemo/QuickStartDemo --name Ada

.\examples\QuickStartDemo\QuickStartDemo.exe --help
.\examples\QuickStartDemo\QuickStartDemo.exe --version
.\examples\QuickStartDemo\QuickStartDemo.exe --name Ada

These show generated usage, hello version 1.0.0, and Hello, Ada!, respectively, with exit status 0. Throughout the guides, tool and myapp stand for your compiled executable; use its actual path.

Choose a CLI shape

Documentation

• Documentation site — navigate by goal.
• Your first cli-fp program — compile and understand the example above.
• How do I...? — short recipes for options, output, completion, the generator, and debugging.
• Current limitations — find the supported boundaries.
• API reference — look up public signatures.
• Technical documentation — architecture and maintainer material.

Examples and generator

The runnable examples progress from QuickStartDemo through root, named, nested, error-handling, colour, and progress applications. They are compiled by the cross-platform cleanup smoke checks.

Use cli-fp-gen when a larger command tree benefits from a scaffolded project layout. It is optional; the program above is the shortest way to start.

Platform notes

• Windows and Linux run the repository's CI checks.
• The runtime has no third-party dependencies. The generator uses FCL JSON units.
• Pascal identifiers, including unit names, are case-insensitive. Linux paths and filenames are case-sensitive: use the files' actual paths and FPC's unit-file lookup conventions (this repository uses lowercase unit files).

Contributing

See the contribution guide. On Windows, run:

powershell -ExecutionPolicy Bypass -File tests\run_tests.ps1
powershell -ExecutionPolicy Bypass -File tests\codegen\run_all_tests.ps1
powershell -ExecutionPolicy Bypass -File tests\run_cleanup_smoke.ps1

The Bash equivalents and the full project map are in the contribution guide.

License

cli-fp is available under the MIT License.