Closure (Groovy 1.7.10)

java.lang.Object
- groovy.lang.GroovyObjectSupport
- - groovy.lang.Closure

All Implemented Interfaces:

GroovyObject, Serializable, Cloneable, Runnable

Direct Known Subclasses:

CurriedClosure, IteratorClosureAdapter, MethodClosure
```
public abstract class Closure
extends GroovyObjectSupport
implements Cloneable, Runnable, Serializable
```
Represents any closure object in Groovy.
Groovy allows instances of Closures to be called in a short form. For example:
```
   def a = 1
   def c = {a}
   assert c() == 1
 
```
To be able to use a Closure in this way with your own subclass, you need to provide a doCall method with any signature you want to. This ensures that getMaximumNumberOfParameters() and getParameterTypes() will work too without any additional code. If no doCall method is provided a closure must be used in its long form like
```
   def a = 1
   def c = {a}
   assert c.call() == 1
 
```
Version:

$Revision: 21242 $

Author:

James Strachan, John Wilson, Jochen Theodorou, Graeme Rocher

See Also:
Serialized Form

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`DELEGATE_FIRST` With this resolveStrategy set the closure will attempt to resolve property references to the delegate first
`static int`	`DELEGATE_ONLY` With this resolveStrategy set the closure will resolve property references to the delegate only and entirely bypass the owner
`static int`	`DONE`
`protected int`	`maximumNumberOfParameters`
`static int`	`OWNER_FIRST` With this resolveStrategy set the closure will attempt to resolve property references to the owner first
`static int`	`OWNER_ONLY` With this resolveStrategy set the closure will resolve property references to the owner only and not call the delegate at all
`protected Class[]`	`parameterTypes`
`static int`	`SKIP`
`static int`	`TO_SELF` With this resolveStrategy set the closure will resolve property references to itself and go through the usual MetaClass look-up process.

Constructor Summary

Constructors
Constructor and Description

Closure(Object owner)
Constructor used when the "this" object for the Closure is null.

Closure(Object owner, Object thisObject)

Constructors
Constructor and Description
`Closure(Object owner)` Constructor used when the "this" object for the Closure is null.
`Closure(Object owner, Object thisObject)`

Method Summary

Methods
Modifier and Type	Method and Description
`Closure`	`asWritable()`
`Object`	`call()` Invokes the closure without any parameters, returning any value if applicable.
`Object`	`call(Object arguments)` Invokes the closure, returning any value if applicable.
`Object`	`call(Object[] args)`
`Object`	`clone()`
`Closure`	`curry(Object[] arguments)` Support for Closure currying.
`Object`	`getDelegate()`
`int`	`getDirective()`
`int`	`getMaximumNumberOfParameters()`
`Object`	`getOwner()`
`Class[]`	`getParameterTypes()`
`Object`	`getProperty(String property)` Retrieves a property value.
`int`	`getResolveStrategy()` Gets the strategy which the closure users to resolve methods and properties
`Object`	`getThisObject()`
`boolean`	`isCase(Object candidate)`
`Closure`	`ncurry(int n, Object[] arguments)` Support for Closure currying at a given index.
`Closure`	`rcurry(Object[] arguments)` Support for Closure "right" currying.
`void`	`run()`
`void`	`setDelegate(Object delegate)` Allows the delegate to be changed such as when performing markup building
`void`	`setDirective(int directive)`
`void`	`setProperty(String property, Object newValue)` Sets the given property to the new value.
`void`	`setResolveStrategy(int resolveStrategy)` Sets the strategy which the closure uses to resolve property references.
`protected static Object`	`throwRuntimeException(Throwable throwable)`

Methods inherited from class groovy.lang.GroovyObjectSupport
getMetaClass, invokeMethod, setMetaClass

Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - OWNER_FIRST
```
public static final int OWNER_FIRST
```
    With this resolveStrategy set the closure will attempt to resolve property references to the owner first
    
    See Also:
    Constant Field Values
  - DELEGATE_FIRST
```
public static final int DELEGATE_FIRST
```
    With this resolveStrategy set the closure will attempt to resolve property references to the delegate first
    
    See Also:
    Constant Field Values
  - OWNER_ONLY
```
public static final int OWNER_ONLY
```
    With this resolveStrategy set the closure will resolve property references to the owner only and not call the delegate at all
    
    See Also:
    Constant Field Values
  - DELEGATE_ONLY
```
public static final int DELEGATE_ONLY
```
    With this resolveStrategy set the closure will resolve property references to the delegate only and entirely bypass the owner
    
    See Also:
    Constant Field Values
  - TO_SELF
```
public static final int TO_SELF
```
    With this resolveStrategy set the closure will resolve property references to itself and go through the usual MetaClass look-up process. This allows the developer to override getProperty using ExpandoMetaClass of the closure itself
    
    See Also:
    Constant Field Values
  - DONE
```
public static final int DONE
```
    See Also:
    Constant Field Values
  - SKIP
```
public static final int SKIP
```
    See Also:
    Constant Field Values
  - parameterTypes
```
protected Class[] parameterTypes
```
  - maximumNumberOfParameters
```
protected int maximumNumberOfParameters
```
- Constructor Detail
  - Closure
```
public Closure(Object owner,
       Object thisObject)
```
  - Closure
```
public Closure(Object owner)
```
    Constructor used when the "this" object for the Closure is null. This is rarely the case in normal Groovy usage.
    
    Parameters:
    owner - the Closure owner
- Method Detail
  - setResolveStrategy
```
public void setResolveStrategy(int resolveStrategy)
```
    Sets the strategy which the closure uses to resolve property references. The default is Closure.OWNER_FIRST
    
    Parameters:
    resolveStrategy - The resolve strategy to set
    See Also:
    DELEGATE_FIRST, DELEGATE_ONLY, OWNER_FIRST, OWNER_ONLY, TO_SELF
  - getResolveStrategy
```
public int getResolveStrategy()
```
    Gets the strategy which the closure users to resolve methods and properties
    
    Returns:
    The resolve strategy
    See Also:
    DELEGATE_FIRST, DELEGATE_ONLY, OWNER_FIRST, OWNER_ONLY, TO_SELF
  - getThisObject
```
public Object getThisObject()
```
  - getProperty
```
public Object getProperty(String property)
```
    Description copied from interface: GroovyObject
    
    Retrieves a property value.
    
    Specified by:
    
    getProperty in interface GroovyObject
    
    Overrides:
    
    getProperty in class GroovyObjectSupport
    
    Parameters:
    property - the name of the property of interest
    
    Returns:
    the given property
  - setProperty
```
public void setProperty(String property,
               Object newValue)
```
    Description copied from interface: GroovyObject
    
    Sets the given property to the new value.
    
    Specified by:
    
    setProperty in interface GroovyObject
    
    Overrides:
    
    setProperty in class GroovyObjectSupport
    
    Parameters:
    property - the name of the property of interest
    newValue - the new value for the property
  - isCase
```
public boolean isCase(Object candidate)
```
  - call
```
public Object call()
```
    Invokes the closure without any parameters, returning any value if applicable.
    
    Returns:
    the value if applicable or null if there is no return statement in the closure
  - call
```
public Object call(Object[] args)
```
  - call
```
public Object call(Object arguments)
```
    Invokes the closure, returning any value if applicable.
    
    Parameters:
    arguments - could be a single value or a List of values
    
    Returns:
    the value if applicable or null if there is no return statement in the closure
  - throwRuntimeException
```
protected static Object throwRuntimeException(Throwable throwable)
```
  - getOwner
```
public Object getOwner()
```
    Returns:
    the owner Object to which method calls will go which is typically the outer class when the closure is constructed
  - getDelegate
```
public Object getDelegate()
```
    Returns:
    the delegate Object to which method calls will go which is typically the outer class when the closure is constructed
  - setDelegate
```
public void setDelegate(Object delegate)
```
    Allows the delegate to be changed such as when performing markup building
    
    Parameters:
    delegate - the new delegate
  - getParameterTypes
```
public Class[] getParameterTypes()
```
    Returns:
    the parameter types of the longest doCall method of this closure
  - getMaximumNumberOfParameters
```
public int getMaximumNumberOfParameters()
```
    Returns:
    the maximum number of parameters a doCall method of this closure can take
  - asWritable
```
public Closure asWritable()
```
    Returns:
    a version of this closure which implements Writable. Note that the returned Writable also overrides Object.toString() in order to allow rendering the result directly to a String.
  - run
```
public void run()
```
    Specified by:
    
    run in interface Runnable
  - curry
```
public Closure curry(Object[] arguments)
```
    Support for Closure currying.
    Typical usage:
```
 def multiply = { a, b -> a * b }
 def doubler = multiply.curry(2)
 assert doubler(4) == 8
 
```
    Note: special treatment is given to Closure vararg-style capability. If you curry a vararg parameter, you don't consume the entire vararg array but instead the first parameter of the vararg array as the following example shows:
```
 def a = { one, two, Object[] others -> one + two + others.sum() }
 assert a.parameterTypes.name == ['java.lang.Object', 'java.lang.Object', '[Ljava.lang.Object;']
 assert a(1,2,3,4) == 10
 def b = a.curry(1)
 assert b.parameterTypes.name == ['java.lang.Object', '[Ljava.lang.Object;']
 assert b(2,3,4) == 10
 def c = b.curry(2)
 assert c.parameterTypes.name == ['[Ljava.lang.Object;']
 assert c(3,4) == 10
 def d = c.curry(3)
 assert d.parameterTypes.name == ['[Ljava.lang.Object;']
 assert d(4) == 10
 def e = d.curry(4)
 assert e.parameterTypes.name == ['[Ljava.lang.Object;']
 assert e() == 10
 assert e(5) == 15
 
```
    Parameters:
    arguments - the arguments to bind
    
    Returns:
    the new closure with its arguments bound
  - rcurry
```
public Closure rcurry(Object[] arguments)
```
    Support for Closure "right" currying. Parameters are supplied on the right rather than left as per the normal curry() method. Typical usage:
```
 def divide = { a, b -> a / b }
 def halver = divide.rcurry(2)
 assert halver(8) == 4
 
```
    Parameters:
    arguments - the arguments to bind
    
    Returns:
    the new closure with its arguments bound
    See Also:
    curry(Object[])
  - ncurry
```
public Closure ncurry(int n,
             Object[] arguments)
```
    Support for Closure currying at a given index. Parameters are supplied from index position "n". Typical usage:
```
 def caseInsensitive = { a, b -> a.toLowerCase() <=> b.toLowerCase() } as Comparator
 def caseSensitive = { a, b -> a <=> b } as Comparator
 def animals1 = ['ant', 'dog', 'BEE']
 def animals2 = animals1 + ['Cat']
 // curry middle param of this utility method:
 // Collections#binarySearch(List list, Object key, Comparator c)
 def catSearcher = Collections.&binarySearch.ncurry(1, "cat")
 [[animals1, animals2], [caseInsensitive, caseSensitive]].combinations().each{ a, c ->
   def idx = catSearcher(a.sort(c), c)
   print a.sort(c).toString().padRight(22)
   if (idx < 0) println "Not found but would belong in position ${-idx - 1}"
   else println "Found at index $idx"
 }
 // =>
 // [ant, BEE, dog]       Not found but would belong in position 2
 // [ant, BEE, Cat, dog]  Found at index 2
 // [BEE, ant, dog]       Not found but would belong in position 2
 // [BEE, Cat, ant, dog]  Not found but would belong in position 3
 
```
    Parameters:
    n - the index from which to bind parameters (may be -ve in which case it will be normalized)
    arguments - the arguments to bind
    
    Returns:
    the new closure with its arguments bound
    See Also:
    curry(Object[])
  - clone
```
public Object clone()
```
    Overrides:
    
    clone in class Object
  - getDirective
```
public int getDirective()
```
    Returns:
    Returns the directive.
  - setDirective
```
public void setDirective(int directive)
```
    Parameters:
    directive - The directive to set.

Class Closure

Field Summary

Constructor Summary

Method Summary

Methods inherited from class groovy.lang.GroovyObjectSupport

Methods inherited from class java.lang.Object

Field Detail

OWNER_FIRST

DELEGATE_FIRST

OWNER_ONLY

DELEGATE_ONLY

TO_SELF

DONE

SKIP

parameterTypes

maximumNumberOfParameters

Constructor Detail

Closure

Closure

Method Detail

setResolveStrategy

getResolveStrategy

getThisObject

getProperty

setProperty

isCase

call

call

call

throwRuntimeException

getOwner

getDelegate

setDelegate

getParameterTypes

getMaximumNumberOfParameters

asWritable

run

curry

rcurry

ncurry

clone

getDirective

setDirective