Some words of explanation about the
set
/unset
/isSet
methods:
The SBML specifications define certain attributes on some classes of
objects as being optional. This requires an application to be careful
about the distinction between two cases when reading a model: (1) a given
attribute has never been set to a value, and therefore should be
assumed to have the SBML-defined default value if one exists, and (2) a
given attribute has been set to a value, but the value happens to be an
empty string. The situation can be ambiguous when reading a model from a
file or data stream and then examining the data objects that libSBML
constructs as a result. LibSBML supports these distinctions by providing
methods to set, unset, and query the status of attributes that are
optional. The methods have names of the form set
Attribute(...)
,
unset
Attribute()
, and
isSet
Attribute()
, where Attribute is the the name of the optional
attribute in question.