Tutorial tour

Welcome to the guided tour of the tutorial!

All the classes in the tutorial are provided with your LibertyEiffel installation, in the tutorial directory.

Easy starting: Hello World!

To compile the program, go to the LibertyEiffel/tutorial directory and execute the command:

se c HELLO_WORLD make -o hello

The meaning of the command is

se	the front-end tool for the LibertyEiffel compiler
c	the tool invoked by se for compile into an executable
HELLO_WORLD	the class of which an object is created (you may also write it in lower-case, or use its filename with the .e extension) we call it root class, as this is the root of the programs object tree
make	the creation procedure of the HELLO_WORLD class to call
-o hello	generates an executable with the name hello (linux) or hello.exe (windows)

The command produces an executable, usually hello or hello.exe depending on the system. After compiling is finished, you can run the executable.

This unavoidable program is in the file hello_world.e and lets you grasp the basic concepts of Eiffel. Those concepts are:

• Everything is a class. In Eiffel, outside classes there is no salvation.
• The program starts by creating an object (of the root class) and initializing it by execution of the given root creation procedure. Here, the make feature in the class HELLO_WORLD.
• Each file is named after the name of the class it contains, in lower-case, with the .e extension.
• Each class comes with a set of features, all its attributes and methods which come in form of functions (if they return a result) or procedures (in case they just 'do' something)
• Note the special object io that allows you to write text on the standard output. We will see that it also lets you read data.
• For the Eiffel syntax, look here.

Please take a look at the following examples in the tutorial folder to see some classical example programs (some of them are in organized in folders for better overview)

• fibonacci.e
• knight.e
• pyramide.e and pyramide2.e
• gcd
• hanoi
• parking
• triangle

To compile the other samples you must obviously modify the compiler command to give another root class .

Some important concepts

Input-output

• io
• directory
• basic_directory?

Arguments

print_arguments.e

Collections

including iterator and sorting

Manifest notations

manifest_notation.e

Downcasting

downcasting.e

To go further

Agents

... and tuples

Memory management

memory

Extension libraries

Vision

visiopn, signal