AssociativeArray

AssociativeArray Class

Objects of class AssociativeArray contain members that are stored and retrieved using Key objects. See Key.

AssociativeArray objects use the atPut and at methods in Collection class to store and retrieve objects. See Collection.

The keyAt method returns the key/value pair of the array element named as its argument.

The map method maps over each object stored in an AssociativeArray, and provides that element as the receiver to the method or code block given as the argument.

If you want to work with the object stored in the array and the key it is stored with, the mapKeys method iterates over each key/value pair of the AssociativeArray

The following example shows how to retreive the keys and values stored in an AssociativeArray. Each value that is stored in the array is a String object, so the program does not need to check for different classes of objects that are stored in the array.

AssociativeArray instanceMethod printValue (void) {

  printf ("%s\t", self name);
  printf ("%s\n", self value);
  return NULL;
}

AssociativeArray instanceMethod printKeyValue (void) {

  String new valueObject;
  printf ("%s =>\t", self name);
  valueObject = self getValue;
  printf ("%s\n", valueObject);
  return NULL;
}

int main () {
  AssociativeArray new assocArray;
  String new s1;
  String new s2;
  String new s3;

  WriteFileStream classInit;
  
  s1 = "string1 value";
  s2 = "string2 value";
  s3 = "string3 value";

  assocArray atPut "string1", s1;
  assocArray atPut "string2", s2;
  assocArray atPut "string3", s3;

  stdoutStream printOn ("%s\n%s\n%s\n\n", (assocArray at "string1"),
			(assocArray at "string2"),
			(assocArray at "string3"));
  stdoutStream printOn "%s\n%s\n%s\n\n", (assocArray at "string1"),
    (assocArray at "string2"),
    (assocArray at "string3");
  stdoutStream printOn "%s\n%s\n%s\n\n", assocArray at "string1",
    assocArray at "string2",
    assocArray at "string3";

  assocArray map printValue;

  assocArray mapKeys printKeyValue;

  return 0;
}

Instance Methods

at (char *key)

Retrieve the element of the receiver array stored at key.

init (...)

= (...)

Append the arguments to the receiver AssociativeArray. The argument list may be any number of key,value pairs. Here is an example.

myAssocArray init "key1", "first", "key2", "second", "key3", "third", 
  "key4", "fourth";
myAssocArray append "key5", "fifth", "key6", "sixth", "key7", "seventh", 
  "key8", "eigth";

... or ... 

myAssocArray = "key1", "first", "key2", "second", "key3", "third", 
  "key4", "fourth";
myAssocArray += "key5", "fifth", "key6", "sixth", "key7", "seventh", 
  "key8", "eigth";

atPut (char *key, OBJECT *item)

Add item to the receiver at key.

init (...)

= (...)

Initializes the receiver AssociativeArray to the values given as the arguments, which may be composed of any number of key,value pairs. Here is an example.

myAssocArray init "key1", "value1", key2", "value2", "key3", "value3";

... or ... 

myAssocArray = "key1", "value1", key2", "value2", "key3", "value3";

keyAt (String keyName)

Returns the Key object named by keyName.

map (OBJECT *(*method)())

Execute method, an instance method of class AssociativeArray, for each member of the receiver array. Each time method is executed, self refers to the object stored in the associativeArray. This method returns NULL.

setValue (void)

A wrapper method for getValue in class Key. If received by an instance of Collection or its subclasses instead of a Key object, this method generates an exception.