Function: value_set
Function: value_setvalue_set (<ident>)
numeric
Whether or not the element of a structure has been set. If it has, the value returned by this function is 1, otherwise 0. This function applies only to elements of user-structures which can inherit class values, or to attributes of dbstructures. For other types of identifiers the result is undefined.
When the element of a structure object has not been set, any references to its value yields a class value from its parent structure. The class value itself may be null.
For dbstructures, which reflect values from an external database, the value returned by this function is a boolean indicating whether an attribute has a non-NULL value in the external database.
<ident>
An element of a
user-structure, e.g. compound, gstructure
or structure.
atable myt
structure ~myt.obj {
string s = 'default'
}
~mytab.obj myobj
tell value_set(myobj.s) ;# Yields 0.
myobj.s = 5
tell value_set(myobj.s) ;# Yields 1.
unset myobj.s
tell value_set(myobj.s) ;# Yields 0.
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