Find attribute attrStr with value valStr, searching in the subhierarchy of concept parentConcept.
returnedBoolean = attrexists(parentConcept, attrStr, valStr)
returnedBoolean - type: bool
parentConcept - type: con
attrStr - type: str
valStr - type: str
1 if any concept below parentConcept has the attribute-value pair, 0 otherwise. Passed a bad concept, the function writes an error to the output log.
The search starts at the named concept, and continues down its entire subhierarchy. Contrast this with attrwithval, which is limited to only the argument concept.
# if you find apples in the concept hierarchy
if (findconcept(findroot(),"apple"))
# kill them (to start fresh)
rmconcept(findconcept(findroot(),"apple"));
# Create the apple concept
G("apple") = makeconcept(findroot(),"apple");
# Apple's color's red
addstrval(G("apple"),"color","red");
# MacIntosh apples are also red
addstrval(makeconcept(G("apple"),"MacIntosh"),"color","red");
# Print out apple's attribute and value
if(attrname(findattrs(G("apple")))){
"output.txt" << "1) apples " << attrname(findattrs(G("apple")));
"output.txt" << " "
<< getstrval(attrvals(findattrs(G("apple")))) << "\n";
}
# Test for a given attribute and value
"output.txt" << "2) are apples red? " <<
attrwithval(G("apple"), "color", "red") << "\n";
"output.txt" << "3) are apples blue? " <<
attrwithval(G("apple"), "color", "blue") << "\n";
# Change a value of a given attribute to another value.
attrchange(findroot(), "color", "red", "blue");
"output.txt" << "4) are apples blue now? " <<
attrwithval(G("apple"), "color", "blue") << "\n";
"output.txt" << "5) " << attrexists(findroot(), "color", "blue");
The code above writes the following to output.txt:
1) apples color red
2) are apples red? 1
3) are apples blue? 0
4) are apples blue now? 1
5) 1