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RoiArthurB edited this page Jul 30, 2026 · 3 revisions

Classes and Objects

GAML 2026 introduces the class and object keywords, bringing full object-oriented programming support beyond species. Classes allow you to define pure data/logic types that are not agents — they have no reflex, no schedule, and no population. They are simply structured values with attributes and methods.

Key concepts

  • A class is a blueprint for creating objects (instances). Declared with class ClassName { ... }.
  • An object is a value created by calling the class constructor: ClassName(attr: value, ...).
  • Classes can have attributes (like species variables) and actions (like species actions, but on objects).
  • Classes support inheritance with parent: ClassName.
  • Classes can be virtual (abstract) with virtual: true — they cannot be instantiated directly.
  • Objects can be stored in any GAML variable, passed as arguments, stored in lists, and used as map keys.

Step-by-Step overview

  • Class Definition and Instantiation — Declare a class, create objects with the constructor syntax ClassName(attr: value), store objects in variables and lists.
  • Attributes and Actions — Read and write attributes (dot notation: obj.attr <- value), call actions (obj.action()), chained calls, comparing objects, passing objects as arguments.
  • Inheritance — Extend a class with parent:, override actions, call parent implementation with super.action(), multi-level inheritance, runtime type testing with is.
  • Virtual Classes — Declare virtual (abstract) classes and virtual (abstract) actions, polymorphism, partial abstract classes, concrete implementations.
  • Advanced Features — Objects as agent attributes, passing objects between agents, objects in species, objects as map keys, object equality.

When to use Classes vs Species

Feature Class Species
Is an agent? No Yes
Has reflex/actions/behaviors? No (methods are plain actions) Yes
Has a population? No (no count or lifecycle) Yes (count, init, lifecycle)
Can be an agent attribute? Yes No (species attributes are values)
Used for? Pure data types, structures, utilities Simulated entities in the world

See also

Home

  1. What's new (Changelog)
  2. Migration Guide (2025-06 → 2026-06)

Platform

  1. Installation and Launching
    1. Installation
    2. Launching GAMA
    3. Updating GAMA
    4. Installing Plugins
  2. Workspace, Projects and Models
    1. Navigating in the Workspace
    2. Changing Workspace
    3. Importing Models
  3. Editing Models
    1. GAML Editor (Generalities)
    2. GAML Editor Tools
    3. Validation of Models
  4. Running Experiments
    1. Launching Experiments
    2. Experiments User interface
    3. Controls of experiments
    4. Parameters view
    5. Inspectors and monitors
    6. Displays
    7. Batch Specific UI
    8. Errors View
  5. Running Headless
    1. Getting Started
    2. Headless Legacy
    3. Headless Batch
  6. Preferences
  7. Troubleshooting

Learn GAML step by step

  1. Introduction
    1. Start with GAML
    2. Organization of a Model
    3. Basic programming concepts in GAML
  2. Manipulate basic Species
  3. Global Species
    1. Regular Species
    2. Defining Actions and Behaviors
    3. Interaction between Agents
    4. Attaching Skills
    5. Inheritance
  4. Defining Advanced Species
    1. Grid Species
    2. Graph Species
    3. Mirror Species
    4. Multi-Level Architecture
  5. Defining GUI Experiment
    1. Defining Parameters
    2. Defining Displays Generalities
    3. Defining 3D Displays
    4. Defining Charts
    5. Defining Monitors and Inspectors
    6. Defining Export files
    7. Defining User Interaction
  6. Classes and Objects
    1. Class Definition and Instantiation
    2. Attributes and Actions
    3. Inheritance
    4. Virtual Classes
    5. Advanced Features
  7. Exploring Models
    1. Run Several Simulations
    2. Batch Experiments
    3. Exploration Methods
  8. Optimizing Models
    1. Runtime Concepts
    2. Analyzing code performance
    3. Optimizing Models
  9. Multi-Paradigm Modeling
    1. Control Architecture
    2. Defining Differential Equations

Recipes

  1. Manipulate OSM Data
  2. Cleaning OSM Data
  3. Diffusion
  4. Using Database
  5. Using Dataframes
  6. Using FIPA ACL
  7. Using BDI with BEN
  8. Using Driving Skill
  9. Manipulate dates
  10. Manipulate lights
  11. Using comodel
  12. Save and restore Simulations
  13. Using network
  14. Writing Unit Tests
  15. Ensure model's reproducibility
  16. Going further with extensions
    1. Calling R
    2. Using Graphical Editor
    3. Using Git from GAMA

GAML References

  1. Built-in Species
  2. Built-in Skills
  3. Built-in Architecture
  4. Statements
  5. Data Type
  6. File Type
  7. Stats Extension
  8. Sound Extension
  9. BDI Extension
  10. FIPA Skill
  11. Expressions
    1. Literals
    2. Units and Constants
    3. Pseudo Variables
    4. Variables And Attributes
    5. Operators (Definition)
    6. Operators [A-A]
    7. Operators [B-C]
    8. Operators [D-H]
    9. Operators [I-M]
    10. Operators [N-R]
    11. Operators [S-Z]
  12. Exhaustive list of GAMA Keywords

Developing GAMA

  1. Installing the development version
    1. Install GAMA source code with Eclipse plugin
  2. Developing Extensions
    1. Developing Plugins
    2. Developing Skills
    3. Developing Statements
    4. Developing Operators
    5. Developing Types
    6. Developing Species
    7. Developing Control Architectures
    8. Index of annotations
  3. Introduction to GAMA Java API
    1. Architecture of GAMA
    2. IScope
  4. Using GAMA flags
  5. Creating a release of GAMA
  6. Documentation generation

Tutorials

  1. Predator Prey
  2. Road Traffic
  3. Incremental Model
  4. Luneray's flu
  5. BDI Agents
  6. Forager RL
  7. SIR Analysis
  8. 3D Model

Community

  1. Team
  2. Projects using GAMA
  3. Scientific References
  4. Training Sessions

Versions of GAMA

Resources

  1. Videos
  2. Conferences
  3. Pedagogical materials

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