Chapter 3
The Element Grouping Class Container
The Element Grouping Class Container (denoted with egC-Container) manages and loads the named element grouping classes. Each element grouping class has its own ELMD descriptor file that describes the attributes of groups, subgroups, and their elements. Here ELMD is a short acronym that stands for Element Metadata Descriptor, and it is used as the file extension in the ELMD descriptor file.The tilde-expansion command ~elmd, when issued at the ASPL prompt, prints the location of the ELMD descriptor file of the currently loaded namedspace. The tilde-expansion command ~egc prints the URL where the last word is the name of the grouping class.
The egC-Container is therefore a loading container that is responsible to load the classes describing the attributes of groups, subgrounds, and their elements. That is the egC-Container contains the classes reponsible to process the metadata characteristics of ASPL groups.
Groups are different and so are their metadata characteristics; hence, to distinguish the groups and their loadable node classes, a unique name is given for each group, and ASPL egC-Container loads each group by name: we will use namedGClass to refer to such a name. For example, the namedGClass ZEROGROUP is the element-grouping-class that is used by the namedspace TRIVIAL. We say that the namedspace TRIVIAL has its metadata defined by the namedGClass ZEROGROUP that is loaded by the egC-Container. Hence, everytime the ASPL interpreter is started by loading the namedspace TRIVIAL, it will also load its corresponding namedGClass ZEROGROUP.
ASPL users do not need to deal with the egC-Container and its specifics, as creating new metadata is left to the ASPL programmer who can use the command metagrouping to create such metadata.
See appendix about the command metagrouping to list the namedGClasses that are visible to your ASPL configuration.
At any time, there is only one element grouping class loaded by the interpreter, which is the grouping class of the currently loaded namedspace. When loading a workspace, ASPL loads the corresponding classes that describe the datasets stored in the workspace, and the user can type the command attributes at the ASPL prompt to display the description of these attributes. The user can ping the currently loaded classes in the egC-Container by typing at the ASPL prompt egCwhoami. The egC-Container is a loading container that is capable to dynamically load the element grouping classes during the runtime of the ASPL interpreter.
