Renaming an Algorithm

Sometime developers will run into situations where the capability of the algorithm grows beyond its original designated name, therefore a renaming of the algorithm is necessary to ensure the name of the algorithm faithfully represent the functionality of given algorithm. This document provides a recommended process to rename the algorithm while avoiding introducing breaking changes for the general users.

Rename C++ Algorithm

Renaming a C++ algorithm can be achieved via the following steps:

• Do a grep search (or use Github search) to locate files that call this algorithms.

• Rename the algorithm (header, source and unit test)

  • Rename the header and set the original name as alias

  #include "MantidAPI/DeprecatedAlias.h"
  ...
  class DLLExport NewAlgName : public API::Algorithm, public API::DeprecatedAlias {
      ...
      const std::string alias() const override { return "OriginalAlgName"; };
      ...
  }
  

  • Set the deprecation date (the date this algorithm name changed) in the constructor in source file

  //-----------------------------------------------------------------------------------
  /** Constructor
  */
  NewAlgName::NewAlgName(){
      setDeprecationDate("2021-09-14"); // date string formatted like the example here
  }
  

  • Update tests

    Unit test and system tests should be the place to start with the renaming update.

  • Update documentation page and corresponding examples

• Update calls within Mantid to use the new Algorithm name

• Make sure list the name change in the release notes

• [Optional] Inform the users about the name change once pull request is merged

  Note

  Script buildconfig/move_class.py can help facilitate the file renaming process of an existing c++ algorithm. More specifically, this script will rename the header, source and unit test files, as well as taking care of the renaming within the corresponding CMake file. Still, the developer needs to dive into the source files to search and replace the class name manually.

  Assumming our algorithm OldAlgName resides in the DataHandling namespace, we would write:

  python2.7 move_class.py DataHandling OldAlgName DataHandling NewAlgName
  

Rename Python Algorithm

Goal: given existing algorithm AlgOldName, we want to rename it to AlgNewName, and AlgOldName will become a deprecated alias of AlgNewName.

• Replace

Replace all occurrences of AlgOldName with AlgNewName in all files. In Linux or Mac:

grep -rl AlgOldName . | xargs sed -i 's/AlgOldName/AlgNewName/g'

The names of some files will need to be replaced. Typically these will be the algorithm file, test file, and documentation

• algOldName.py (becomes “algNewName.py”)

• algOldNameTest.py (becomes “algNewNameTest.py”)

• algOldName-v1.rst (becomes “algNewName-v1.rst”)

• Edit

Edit algNewName.py. We need to add and alias method and mark the algorithm with the alias deprecator

Below are the relevant statements to deprecate the alias on Christmas day of the year 2025

from mantid.utils.deprecator import alias_deprecated

@deprecated_alias('2025-12-25')
class AlgNewName(PythonAlgorithm):

    def alias(self):
        r"""Alternative name to this algorithm"""
        return 'algOldName'

Configuration

Upon using a deprecated alias to invoke an algorithm, a message will be printed in the log at the error level. For instance, when using deprecated alias algOldName in place of the algorithm’s name algNewName, the following error message is printed:

Algorithm alias algOldName is deprecated. Use algNewName instead

If so desired, the user can raise a RuntimeError by setting property algorithms.alias.deprecated to Raise in the user properties file $HOME/.mantid/Mantid.user.properties or in a script:

from mantid.kernel import ConfigService
config = ConfigService.Instance()
config['algorithms.alias.deprecated'] = 'Raise'

Coming to our previous example, a RuntimeError is printed:

RuntimeError: Use of algorithm alias algOldName not allowed. Use algNewName instead
File "/home/username/my_script.py", line 9, in <module>
    def alias(self):
File "/path/to/mantid/Framework/PythonInterface/mantid/simpleapi.py", line 1032, in __call__
    raise RuntimeError(f'Use of algorithm alias {self._alias.name} not allowed. Use {name} instead')

To prevent the RuntimeError and instead print a log error message, the property can be left unset or set to “Log”.