Development guidelines

File hierarchy

The following describes how libraries and tools should be organised in a file hierarchy.


Organisation of libraries:

  • A library named foo is located in the directory libraries/foo.

  • Each library directory has the following directory structure:




    Sample program files


    Header files


    Source files which must be compiled to build the library


    Regression or other test programs or scripts

  • Include files belonging to library foo must be placed in the directory include/mcrl2/foo.

  • Library code is put in the namespace mcrl2::foo,


Organisation of tools:

  • A tool named foo is located in the directory tools/foo.

  • Each tool directory has the following directory structure:




    Regression or other test programs or scripts

  • Build files, source files and include files are located in the tool directory itself.

  • Reusable code must be put in a library, not in a tool!


Some of these guidelines were taken from


Except for third party software, every header and source file should adhere to the following guidelines.


Every file should start with a preamble containing author names and links to copying and license information. The preamble should be formatted as follows, where AUTHORS stands for the names of the authors:

// Author(s): AUTHORS
// Copyright: see the accompanying file COPYING or copy at
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at

Naming conventions

The following naming conventions regarding filenames should be used:

  • Filenames should be all lowercase.

  • The following file extensions should be used: * .cpp for source files; * .h for header files.

The following naming conventions regarding file contents should be used:

  • Names (except as noted below) should be all lowercase, with words separated by underscores.

  • Template parameter names begin with an uppercase letter.

  • Macro names all uppercase and begin with MCRL2_.

  • Choose meaningful names - explicit is better than implicit, and readability counts. There is a strong preference for clear and descriptive names, even if lengthy.

Header policy

The following guidelines are specific to header files (based on

  • Unless multiple inclusion is intended, wrap the header in #ifndef guards with The name MCRL2_LIBRARY_PATH_TO_INCLUDE.

  • Wrap the header contents in a namespace to prevent global namespace pollution. mCRL2 libraries should be placed in the namespace mcrl2.

  • Make sure that a translation unit consisting of just the contents of the header file will compile successfully. In other words, a source file with content #include “foo.h” should compile for every header file foo.h.

  • Place the header file in a sub-directory to prevent conflict with identically named header files in other libraries.

  • To avoid namespace pollution, the use of the using and using namespace directives is not allowed at the global parts of the header.

The following is a sample header:

// Author(s): AUTHORS
// Copyright: see the accompanying file COPYING or copy at
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
/// \file FILE_NAME

#ifndef MCRL2_MY_CLASS_H
#define MCRL2_MY_CLASS_H

namespace mcrl2 {

  class my_class
      void f();
      int x;

} // namespace

#endif  // MCRL2_MY_CLASS_H

Exception handling

Use exceptions to report errors where appropriate, and write code that is safe in the face of exceptions.

Standards compliance

Aim for ISO Standard C++. That means making effective use of the standard features of the language, and avoiding non-standard compiler extensions. It also means using the C++ Standard Library where applicable.

Regression tests

Provide a regression test program or programs.


Provide sample programs or confidence tests so potential users can see how to use your library.

Platform independence

The source code must compile on the actively supported platforms and supported build tools on those platforms.

Committing changes

When committing changes, the following guidelines should be adhered to:

  • Make sure the updated code successfully compiles, installs, and passes all tests.

  • Enter a clear commit message.

  • Whenever a commit solves a Trac ticket, the commit message must refer to the ticket by its number, formatted as fixes #n, where n represents the ticket number. This automatically closes the ticket with a reference to the commit number and message.

Documentation guidelines

This page describes the documentation guidelines for tools and libraries.


Tool documentation should consists of help information and a user manual. The help information is described in the tool interface guidelines, the user manual is described here.

User manual

The tool use manual is automatically generated from the help description of the tool, provided that the tool uses the Tool classes. We therefore require that all tools use the tool classes.


Library documentation should consist of a user manual and reference manual. Both should be available on the library documentation page.

User manual

The library user manual provides an informal explanation of the library and its use. It should consist of the following sections (in that order):

  • Introduction

  • Concepts

  • Structure

  • Tutorial

  • References (if any)

  • Acknowledgements (if needed)

  • Authors: the line Written by AUTHORS. where AUTHORS stands for the names of the authors.

  • Reporting bugs: Report bugs at our issue tracking system <>.

Reference manual

The library reference manual provides a technical specification of the library. It should consist of an explanation of all used elements in the public interface. This manual should be automatically generated from the library code using Doxygen comments. The current convention is that only documented code will be displayed, unless the internal command is included in the Doxygen comment. Library code located in a detail sub-directory is considered to be no part of the public interface, and no documentation is generated for this code.

Doxygen documentation should specified as follows:

  • For each directory and file in the public interface, structural commands \dir and \file should be used.

  • For each file member in the public interface, a special documentation block should be put directly above the file member. File members include, but are not limited to, namespaces, classes, structs, unions, enums, functions, variables, defines and typedefs.

In the above specified documentation, the following Doxygen special commands should be used:

  • \brief: a one-line description for each directory, file, and file member in the public interface.

  • \param: a parameter description for each parameter of a public function.

  • \return: a return value description for each non-void public function.


The following documentation guidelines apply to both tools and libraries.


All tools and libraries should acknowledge authors of used or “inspirational” code. This does include but is certainly not limited to fulfilling license requirements. Acknowledgements are required in the following cases:

  • The use of code - altered or not - of third parties.

  • The use of algorithms, data structures, architectures etc. designed by third parties.

  • The use of third-party code, tools, algorithms etc. as an inspirational basis.

However, things regarded as common knowledge are excluded from the latter two requirements.

Besides these requirements, authors of the mCRL2 toolset are highly encouraged to add references to related work (similar to adding related work in a paper).

Some examples to illustrate:

  • Copying a snippet of code ad verbatim from outside the mCRL2 toolset requires acknowledgements.

  • Modifying such a piece of code does not change this.

  • Implementing quicksort <> does not require acknowledgements as it can be considered common knowledge. This does ‘’not’’ include using a third-party implementation of quicksort; acknowledgements to the author of that implementation are required.

  • Implementation of an algorithm found in an article should refer to that article.

  • When implementing a tool with a similar third-party tool in mind, one should refer to that third-party tool as source of inspiration.

We distinguish three types of acknowledgements:

  1. full: This means that all relevant information should be given. That is,

    authors, articles, original source location and a description of the precise use of the code etc.

  2. summary: A summary of the information of ‘’full’’. This should include the

    authors, article name and functionality description.

  3. short summary: Even shorter variant of the ‘’summary’’. This should only

    include authors or article name and the functionality.

Some examples to illustrate:

  • full: “The following function is based on the algorithm in A.U. Thor,

    “Algorithms for Dummies”, Publish Inc., 1975. I have changed the data structure a bit such that lookup is now O(log(n)) instead of O(n).”

  • summary: “Shribbing functionality based on A.U. Thor, “Algorithms for Dummies”.”

  • short summary: “Algorithms for Dummies (shribbing)”

Where to acknowledge and to what extent:

  • Within a source file full acknowledgements should be added at relevant places. The only exception is a source file that as a whole is taken ad verbatim and already includes the relevant information (such as a license).

  • Library documentation of functions should contain or refer to summary acknowledgements (but not to those within the source code itself). It is possible to group acknowledgements and put them all in one place as long as it is clear what the acknowledgements refer to.

  • A library’s user manual should contain summary acknowledgements.

  • A tool’s manual page should contain summary acknowledgements.

  • When a tool’s core functionality is part of a library and this part has acknowledgements, the tool itself should also acknowledge. This may be in a short form with a reference to the full(er) acknowledgement in the library. (For instance, when library X has function F with certain acknowledgements and one of the main tasks of a tool is to read a file apply F and return the result, then the tool should include the acknowledgements for F.)