BDKeyValueQualifier

Inherits from:
BDQualifier
NSObject
Conforms to:
BDQualifierEvaluation
NSCoding
Declared in:
BDControl/BDKeyValueQualifier.h

Class at a Glance

A BDKeyValueQualifier compares the value of an attribute of the object the qualifier is evaluated against with a static value. The value may be a variable.


Class Description

To compare an attribute of an object against a value, a BDKeyValueQualifier is used. Instances of BDKeyValueQualifier use the standard BDQualifier comparison selectors to perform comparisons.

The value the attribute is compared against may be another object, a null object, or a variable. If the value is a null object (either nil or an instance of NSNull), the only applicable comparison selectors are BDQualifierOperatorEqual and BDQualifierOperatorNotEqual.

If the value is a variable, the qualifier can't be evaluated directly; it must be sent -qualifierWithBindings:requiresAllVariables: to get a qualifier that can be evaluated. -qualifierWithBindings:requiresAllVariables: may throw an exception if all variables are required to be bound and a variable could not be found in the bindings dictionary passed to the method. If not all variables are required to be bound, and the binding for a variable isn't found, it may return nil to indicate that the qualifier cannot be evaluated.


Adopted Protocols

BDQualifierEvaluation
-evaluateWithObject:
NSCoding
-encodeWithCoder:
-initWithCoder:

Method Types

Initialization
-initWithKey:operatorSelector:value:
 
Accessors
-key
-operatorSelector
-value

Instance Methods

initWithKey:operatorSelector:value:

- (id)initWithKey:(NSString *)key operatorSelector:(SEL)operatorSelector value:(id)value

Initializes an instance of BDKeyValueQualifier with the key and value to compare and the comparison operation to use.

key

- (NSString *)key

Returns the key.

operatorSelector

- (SEL)operatorSelector

Returns the selector used to compare the value of the key and the specified value when the qualifier is evaluated.

value

- (id)value

Returns the value to compare against.


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