Lazarus (IDE)

Lazarus is a cross-platform, integrated development environment (IDE) for rapid application development (RAD) using the Free Pascal compiler. Its goal is to provide an easy-to-use development environment for developing with the Object Pascal language, which is as close as possible to Delphi. It is free and open-source software with different parts released under different software licenses.

Lazarus is often used to create native-code console and graphical user interface (GUI) applications for desktop computers, mobile devices, web applications, web services, visual components, and function libraries for several different operating system platforms, including macOS, Linux, and Windows.

A project created by using Lazarus on one platform can be compiled on any other one which Free Pascal compiler supports. For desktop applications, one source code can target macOS, Linux, and Windows, with little or no modification. For example, the Lazarus IDE is created from one code base and available on all major platforms including Raspberry Pi.

Features

Lazarus provides a ''What You See Is What You Get'' (WYSIWYG) development environment for creating rich user interfaces, application logic, and other supporting code artifacts, similar to Delphi. Along with project management features, the Lazarus IDE also provides:

* A visual windows layout designer
* GUI widgets or visual components such as edit boxes, buttons, dialogs, menus, etc.
* Non-visual components for common behaviors such as persistence of application settings
* Data-connectivity components for MySQL, PostgreSQL, FireBird, Oracle, SQLite, Sybase, and others
* Data-aware widget set that allows the developer to see data in visual components in the designer to assist with development
* Interactive debugger
* Code completion
* Code templates
* Syntax highlighting
* Context-sensitive help
* Text resource manager for internationalization
* Automatic code formatting
* Extensibility via custom components

Cross-platform development

Lazarus uses Free Pascal as its back-end compiler. As Free Pascal supports cross-compiling, Lazarus applications can be cross-compiled from Windows, Linux, or macOS to any of the supported Free Pascal compilation targets. Applications for embedded devices (smartphones, PDAs, routers, game consoles) can be cross-compiled from any desktop platform.

Lazarus provides a cross-platform application framework called the Lazarus Component Library (LCL), which provides a single, unified interface for programmers, with different platform-specific implementations. Using LCL, it is possible to create applications in a ''write once, compile anywhere'' manner, unless system-dependent features are used explicitly. LCL was originally modeled after the Visual Component Library (VCL) in Delphi 6, but is not restricted to Windows. This is done by separating the definition of common widget classes and their widgetset-specific implementation. Each widget set is supported by providing an ''interface'' which interacts directly with the set.

Database development

Developers can install packages that allow Lazarus to support several database management systems (DBMSes). Programs can interact with a DBMS through code or by components dropped on a form.

The following DBMSes are supported out of the box:

* dBase and FoxPro,
* InterBase and Firebird
* Microsoft SQL Server and Sybase ASE
* MySQL and MariaDB
* Open Database Connectivity (ODBC) databases
* Oracle Database
* PostgreSQL
* SQLite

Differences from Delphi

Lazarus resembles Delphi in many ways. It supports Component Object Model (COM) since version 2.2.0, and offers most of Delphi's networking functions. However, there are limits to the performance and feature set.

Lazarus does not support the following, which Delphi does:

* Datasnap (uses Embarcadero proprietary enterprise functions, not a publicly documented system)
* Dynamically loadable packages
* .NET libraries (.NET code, however, can invoke Object Pascal code or anything other machine-native library via Platform Invocation Services.)
* Extensive Microsoft Office connectivity (Lazarus can only open Microsoft Excel with a simple table filled out.)

LCL is not fully compatible with VCL. This makes the extensive repository of available VCL widgets inaccessible without conversion. The conversion effort mostly involves some editing, although there are a few fundamental differences. When porting, missing units in the libraries are a considerably bigger problem than incompatibilities between LCL and VCL. Components for Delphi can be converted to work in Lazarus. This can be complex, though less so than for Lazarus versions older than 0.9.30, based on FP 2.4.x.

On Windows, the default size of an executable file is larger than the Delphi 6 or 7 equivalent, as Lazarus stores debug information within the executable, rather than as separate files. Starting with version 0.9.30, Lazarus supports external debug symbols via compiler options. Thus, program file sizes can be significantly reduced. Alternatively, debug info can be stripped from EXEs (e.g. using a port of the UNIX strip command).

Distribution and licensing

Like Free Pascal, Lazarus is free software. Different portions are distributed under different free software licenses, including GPL, LGPL, MPL, and a modified version of LGPL. LCL, which is statically built into the produced executables, is licensed under a modified version of the LGPL, granting extra permissions to allow it to be statically built into the produced software, including proprietary

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