Delphi

Delphi represents one of the most significant developments in programming history - a rapid application development (RAD) environment that made Windows programming accessible to millions of developers while producing fast, native executables.

History & Origins

In the early 1990s, Windows development was painful. Microsoft’s Visual Basic offered ease of use but poor performance. C++ provided speed but was complex and error-prone. Borland’s Anders Hejlsberg (who would later create C# and TypeScript) led the development of Delphi to bridge this gap.

Released in 1995, Delphi combined:

1. The elegance of Pascal - Clean, readable syntax
2. Object-oriented programming - Full OOP with classes, inheritance, interfaces
3. Visual component framework - Drag-and-drop GUI building
4. Blazing compilation - Inherited from Turbo Pascal’s legendary speed
5. Native code generation - No runtime dependencies, fast executables

The RAD Revolution

Delphi’s visual form designer was revolutionary. Developers could:

• Drag components onto forms visually
• Set properties in an object inspector
• Double-click to generate event handler code
• Build complete applications in hours, not weeks

This approach was so successful that Microsoft hired Anders Hejlsberg and based much of C# and Visual Studio’s design on Delphi concepts.

Delphi vs Pascal

While Delphi uses Object Pascal as its language, it’s more than just Pascal with objects:

Why Delphi Still Matters

1. Rapid Development

Delphi’s component-based architecture enables extremely fast development. Complex database applications, network tools, and business software can be built in a fraction of the time required by other compiled languages.

2. Native Performance

Unlike interpreted languages or those requiring virtual machines, Delphi compiles directly to native code. Applications start instantly and run efficiently without runtime dependencies.

3. Windows Integration

No language integrates more seamlessly with Windows. Delphi provides direct access to the Windows API, COM objects, and system services while abstracting away the complexity.

4. Cross-Platform (Modern Delphi)

Modern Delphi with FireMonkey supports:

• Windows (32-bit and 64-bit)
• macOS
• iOS
• Android
• Linux

5. Maintainability

Code written in Delphi 1 (1995) can often still compile in modern Delphi with minimal changes - a testament to the language’s design stability.

Free Pascal: The Open-Source Alternative

For those who can’t or don’t want to use commercial Delphi, Free Pascal (FPC) provides an excellent alternative:

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# Run Free Pascal in Delphi mode
fpc -Mdelphi myprogram.dpr

# Or use the default Object Pascal mode
fpc myprogram.pas

Free Pascal supports:

• Delphi 7 compatibility mode
• Modern Object Pascal features
• Multiple platforms (Windows, Linux, macOS, FreeBSD, and more)
• The Lazarus IDE (Delphi-like RAD environment)

Language Features

Properties

Delphi introduced the property concept that’s now common in many languages:

type
  TPerson = class
  private
    FName: string;
    FAge: Integer;
  public
    property Name: string read FName write FName;
    property Age: Integer read FAge write SetAge;
  end;

Interfaces

Full interface support for component-based design:

type
  ILogger = interface
    procedure Log(const Message: string);
  end;

  TFileLogger = class(TInterfacedObject, ILogger)
    procedure Log(const Message: string);
  end;

Exception Handling

Structured exception handling with familiar try/except/finally:

try
  Result := StrToInt(UserInput);
except
  on E: EConvertError do
    ShowMessage('Please enter a valid number');
end;

Getting Started

Delphi code is typically organized as:

• .dpr - Project file (main program)
• .pas - Unit files (modules)
• .dfm - Form definition files (visual forms)

A simple console program:

program HelloWorld;

{$APPTYPE CONSOLE}

begin
  WriteLn('Hello, World!');
end.

Continue to the Hello World tutorial to write your first Delphi program.