Configuration (REEF Tang 0.13.0-incubating API)

All Known Implementing Classes:

ConfigurationImpl
```
public interface Configuration
```
Immutable, type-checked configuration data.
Tang Configuration objects are constructed via ConfigurationBuilders, and most applications interact with the Configuration API much more than the one described here. See the ConfigurationBuilder documentation for a discussion of the semantics of configuration options. The documentation provided here is primarily for people that wish to extend Tang or implement formats that export data from Configuration objects to other systems.
Conceptually, a configuration contains a set of key value pairs. Each pair either maps from an interface to an implementation (a class) or from a configuration option to a value (e.g., an integer or string).
Under the hood, Configuration objects carry much richer type information than this, and also refer to the ClassHierarchy object they were checked against. Configurations can be merged into each other by creating a new ConfigurationBuilder object, and passing in multiple configurations. In such situations, Tang automatically merges the reflection data from the underlying ClassHierarchy objects, and re-validates the merged configuration data against the merged classpath.
Note that the left hand side of each configuration object (the "key" in the key value pair) is unique. Although there are many APIs that take NamedParameterNode objects in this API, a given NamedParameterNode represents a unique type of binding, and is only applicable to one of the getters below. These APIs use Java generic types to make it easier to map from NamedParameterNode to the appropriate getter.

Method Summary

Methods
Modifier and Type	Method and Description
`<T> ClassNode<ExternalConstructor<T>>`	`getBoundConstructor(ClassNode<T> cn)`
`Set<ClassNode<?>>`	`getBoundConstructors()`
`<T> ClassNode<T>`	`getBoundImplementation(ClassNode<T> cn)`
`Set<ClassNode<?>>`	`getBoundImplementations()`
`List<Object>`	`getBoundList(NamedParameterNode<List<?>> np)` Get the list bound to a given NamedParameterNode.
`Set<NamedParameterNode<List<?>>>`	`getBoundLists()`
`Set<Object>`	`getBoundSet(NamedParameterNode<Set<?>> np)` Obtain the set of class hierarchy nodes or strings that were bound to a given NamedParameterNode.
`Set<NamedParameterNode<Set<?>>>`	`getBoundSets()`
`ClassHierarchy`	`getClassHierarchy()` Configuration objects are associated with the ClassHierarchy objects that were used during validation.
`<T> ConstructorDef<T>`	`getLegacyConstructor(ClassNode<T> cn)` Return the LegacyConstructor that has been bound to this Class.
`Set<ClassNode<?>>`	`getLegacyConstructors()`
`String`	`getNamedParameter(NamedParameterNode<?> np)` Return the value of the given named parameter as an unparsed string.
`Set<NamedParameterNode<?>>`	`getNamedParameters()`
`ConfigurationBuilder`	`newBuilder()` Create a new ConfigurationBuilder object based on the same classpath as this Configuration, and populate it with the configuration options of this object.

- Method Detail
  - newBuilder
```
ConfigurationBuilder newBuilder()
```
    Create a new ConfigurationBuilder object based on the same classpath as this Configuration, and populate it with the configuration options of this object.
    This API is unstable and should be considered private. Use the methods in org.apache.reef.Tang instead.
  - getNamedParameter
```
String getNamedParameter(NamedParameterNode<?> np)
```
    Return the value of the given named parameter as an unparsed string.
    If nothing was explicitly bound, this method returns null (it does not return default values).
    
    Parameters:
    np - A NamedParameter object from this Configuration's class hierarchy.
    
    Returns:
    The validated string that this parameter is bound to, or null.
    See Also:
    getClassHierarchy()
  - getBoundSet
```
Set<Object> getBoundSet(NamedParameterNode<Set<?>> np)
```
    Obtain the set of class hierarchy nodes or strings that were bound to a given NamedParameterNode. If nothing was explicitly bound, the set will be empty (it will not reflect any default values).
    
    Parameters:
    np - A NamedParameterNode from this Configuration's class hierarchy.
    
    Returns:
    A set of ClassHierarchy Node objects or a set of strings, depending on whether the NamedParameterNode refers to an interface or configuration options, respectively.
    See Also:
    getClassHierarchy()
  - getBoundList
```
List<Object> getBoundList(NamedParameterNode<List<?>> np)
```
    Get the list bound to a given NamedParameterNode. The list will be empty if nothing was bound.
    
    Parameters:
    np - Target NamedParameter
    
    Returns:
    A list bound to np
  - getBoundConstructor
```
<T> ClassNode<ExternalConstructor<T>> getBoundConstructor(ClassNode<T> cn)
```
    Returns:
    the external constructor that cn has been explicitly bound to, or null. Defaults are not returned.
  - getBoundImplementation
```
<T> ClassNode<T> getBoundImplementation(ClassNode<T> cn)
```
    Returns:
    the implementation that cn has been explicitly bound to, or null. Defaults are not returned.
  - getLegacyConstructor
```
<T> ConstructorDef<T> getLegacyConstructor(ClassNode<T> cn)
```
    Return the LegacyConstructor that has been bound to this Class. Such constructors are defined in the class, but missing their @Inject annotation.
    For now, only one legacy constructor can be bound per class.
    TODO: Should this return Set> instead?
  - getBoundImplementations
```
Set<ClassNode<?>> getBoundImplementations()
```
    Returns:
    the set of all interfaces (or super-classes) that have been explicitly bound to an implementation sub-class.
  - getBoundConstructors
```
Set<ClassNode<?>> getBoundConstructors()
```
    Returns:
    the set of all the interfaces that have had an external constructor bound to them.
  - getNamedParameters
```
Set<NamedParameterNode<?>> getNamedParameters()
```
    Returns:
    the set of all the named parameters that have been explicitly bound to something.
  - getLegacyConstructors
```
Set<ClassNode<?>> getLegacyConstructors()
```
    Returns:
    the set of all interfaces that have a legacy constructor binding.
  - getClassHierarchy
```
ClassHierarchy getClassHierarchy()
```
    Configuration objects are associated with the ClassHierarchy objects that were used during validation.
    
    Returns:
    the ClassHierarchy that backs this Configuration.
  - getBoundSets
```
Set<NamedParameterNode<Set<?>>> getBoundSets()
```
    Returns:
    the set of all NamedParameterNodes explicitly bound to sets.
  - getBoundLists
```
Set<NamedParameterNode<List<?>>> getBoundLists()
```
    Returns:
    the set of all NamedParameterNodes explicitly bound to lists.

Interface Configuration

Method Summary

Method Detail

newBuilder

getNamedParameter

getBoundSet

getBoundList

getBoundConstructor

getBoundImplementation

getLegacyConstructor

getBoundImplementations

getBoundConstructors

getNamedParameters

getLegacyConstructors

getClassHierarchy

getBoundSets

getBoundLists