DataDescription Manual

Table of Contents

• About
• Description
• Database
• Further Reading

About

A DataDescription contains settings that describe the attributes of a data type. While a maxon::DataDescriptionDefinitionInterface contains the "raw" definition the maxon::DataDescriptionInterface includes the complete, resolved description.

Description

The data in a DataDescription is stored as a DataDictionary.

General information (maxon::DESCRIPTION::DATA::INFO) is accessed with:

• maxon::DataDescriptionInterface::GetInfo(): Returns the info dictionary.
• maxon::DataDescriptionInterface::SetInfo(): Sets the info dictionary.

The various attribute descriptions in the description are stored as DataDictionaries:

• maxon::DataDescriptionInterface::GetEntryCount(): Returns the number of stored entries.
• maxon::DataDescriptionInterface::GetEntries(): Returns all entries.
• maxon::DataDescriptionInterface::GetEntry(): Returns the entry at the given index.
• maxon::DataDescriptionInterface::SetEntry(): Adds or merges the given entry.
• maxon::DataDescriptionInterface::EraseEntry(): Deletes an attribute with the given ID from the description.
• maxon::DataDescriptionInterface::Reset(): Resets the description and clears all attributes.

  // This example loads the description of the given data type and prints the attributes to the console.
 
  // data type ID
  const maxon::Id dataType { "net.maxonexample.class.descriptionElement" };
 
  // load description data
  maxon::Id category = maxon::DATADESCRIPTION_CATEGORY_DATA;
  const maxon::DataDescription descriptionData = maxon::DataDescriptionDatabaseInterface::LoadDescription(category, maxon::LanguageRef(), dataType) iferr_return;
 
  // load description string data
  category = maxon::DATADESCRIPTION_CATEGORY_STRING;
  const maxon::LanguageRef     language = maxon::Resource::GetDefaultLanguage();
  const maxon::DataDescription descriptionStrings = maxon::DataDescriptionDatabaseInterface::LoadDescription(category, language, dataType) iferr_return;
 
  // list all attributes
 
  const auto attributes = descriptionData.GetEntries() iferr_return;
 
  for (const maxon::DataDictionary& attribute : attributes)
  {
    // get attribute settings
 
    const maxon::InternedId ID = attribute.Get(maxon::DESCRIPTION::BASE::IDENTIFIER) iferr_return;
    const maxon::Id         attributeDataType = attribute.Get(maxon::DESCRIPTION::DATA::BASE::DATATYPE) iferr_return;
    const maxon::Data       defaultData = attribute.Get(maxon::DESCRIPTION::DATA::BASE::DEFAULTVALUE) iferr_return;
 
    DiagnosticOutput("Attribute \"@\" of type @. Default value: @", ID, attributeDataType, defaultData);
 
    // get localized attribute name
 
    ifnoerr (const maxon::DataDictionary attributeString = descriptionStrings.GetEntry(ID))
    {
      const maxon::String translatedString = attributeString.Get(maxon::DESCRIPTION::STRING::BASE::TRANSLATEDSTRING) iferr_return;
      DiagnosticOutput("Name: \"@\" (@)", translatedString, language.GetName());
    }
  }

It is possible to compare two descriptions with:

• maxon::DataDescriptionInterface::IsEqual(): Returns if the description is equal to the given description.
• maxon::DataDescriptionInterface::Compare(): Compares the description and the given description and returns the result.
• maxon::DataDescriptionInterface::GetHashCode(): Returns a hash value for the description.

Database

The data descriptions are stored in the maxon::DataDescriptionDatabaseInterface database.

• maxon::DataDescriptionDatabaseInterface::LoadDescription(): Returns the description of the given data type.
• maxon::DataDescriptionDatabaseInterface::StoreDescription(): Stores the description of the given data type.
• maxon::DataDescriptionDatabaseInterface::GetEffectiveEnumList(): Returns an enumeration list prepared for display in the UI.

  // This example lists all registered data descriptions and the number of defined attributes.
 
  // get all registered descriptions
 
  const maxon::Id category = maxon::DATADESCRIPTION_CATEGORY_DATA;
  const maxon::Id descriptionID { "net.maxonexample.class.descriptionElement" };
 
  // load description
  const maxon::DataDescription description = maxon::DataDescriptionDatabaseInterface::LoadDescription(category, maxon::LanguageRef(), descriptionID) iferr_return;
 
  // get number of attributes
  const maxon::Int count = description.GetEntryCount();
 
  DiagnosticOutput("Data type @ has @ attributes.", descriptionID, count);
 

Further Reading

• Data Descriptions
• Data Description Categories and Keys
• DataDescriptionDefinition Manual
• DataDescriptionObjectInterface Manual
• DataDictionary Manual
• Resource IDs