Package groovy.lang

Interface MetaObjectProtocol

All Known Subinterfaces:
AdaptingMetaClass, MetaClass, MutableMetaClass
All Known Implementing Classes:
ClosureMetaClass, DelegatingMetaClass, ExpandoMetaClass, HandleMetaClass, MetaClassImpl, MixedInMetaClass, MockProxyMetaClass, OwnedMetaClass, ProxyMetaClass
public interface MetaObjectProtocol

An interface that defines the API usable by clients of Groovy's Meta Object Protocol (MOP). These methods are implemented by the reference implementation of the MetaClass interface.

See Also:

  • Method Details

    • getProperties

      List<MetaProperty> getProperties()
      Obtain a list of all meta properties available on this meta class
      Returns:
      A list of MetaProperty instances
      See Also:

    • getMethods

      List<MetaMethod> getMethods()
      Obtain a list of all the meta methods available on this meta class
      Returns:
      A list of MetaMethod instances
      See Also:

    • respondsTo

      List<MetaMethod> respondsTo(Object obj, String name, Object[] argTypes)

      Returns an object satisfying Groovy truth if the implementing MetaClass responds to a method with the given name and arguments types.

      Note that this method's return value is based on realised methods and does not take into account objects or classes that implement invokeMethod or methodMissing

      This method is "safe" in that it will always return a value and never throw an exception

      Parameters:
      obj - The object to inspect
      name - The name of the method of interest
      argTypes - The argument types to match against
      Returns:
      A List of MetaMethods matching the argument types which will be empty if no matching methods exist

    • respondsTo

      List<MetaMethod> respondsTo(Object obj, String name)

      Returns an object satisfying Groovy truth if the implementing MetaClass responds to a method with the given name regardless of arguments. In other words this method will return for foo() and foo(String).

      Note that this method's return value is based on realised methods and does not take into account objects or classes that implement invokeMethod or methodMissing

      This method is "safe" in that it will always return a value and never throw an exception

      Parameters:
      obj - The object to inspect
      name - The name of the method of interest
      Returns:
      A List of MetaMethods which will be empty if no methods with the given name exist

    • hasProperty

      MetaProperty hasProperty(Object obj, String name)

      Returns true of the implementing MetaClass has a property of the given name

      Note that this method will only return true for realised properties and does not take into account implementation of getProperty or propertyMissing

      Parameters:
      obj - The object to inspect
      name - The name of the property
      Returns:
      The MetaProperty or null if it doesn't exist

    • getMetaProperty

      MetaProperty getMetaProperty(String name)
      Returns a MetaProperty for the given name or null if it doesn't exist
      Parameters:
      name - The name of the MetaProperty
      Returns:
      A MetaProperty or null

    • getStaticMetaMethod

      MetaMethod getStaticMetaMethod(String name, Object[] args)
      Retrieves a static MetaMethod for the given name and argument values, using the types of the arguments to establish the chosen MetaMethod
      Parameters:
      name - The name of the MetaMethod
      args - The argument types
      Returns:
      A MetaMethod or null if it doesn't exist

    • getMetaMethod

      MetaMethod getMetaMethod(String name, Object[] args)
      Retrieves an instance MetaMethod for the given name and argument values, using the types of the argument values to establish the chosen MetaMethod
      Parameters:
      name - The name of the MetaMethod
      args - Array containing - 1) the argument values (using which their types are then inferred), or 2) the corresponding argument types
      Returns:
      A MetaMethod or null if it doesn't exist

    • getTheClass

      Class getTheClass()
      Retrieves that Java Class that the attached Meta behaviours apply to
      Returns:
      The java.lang.Class instance

    • invokeConstructor

      Object invokeConstructor(Object[] arguments)
      Invokes a constructor for the given arguments. The MetaClass will attempt to pick the best argument which matches the types of the objects passed within the arguments array
      Parameters:
      arguments - The arguments to the constructor
      Returns:
      An instance of the java.lang.Class that this MetaObjectProtocol object applies to

    • invokeMethod

      Object invokeMethod(Object object, String methodName, Object[] arguments)
      Invokes a method on the given Object with the given name and arguments. The MetaClass will attempt to pick the best method for the given name and arguments. If a method cannot be invoked a MissingMethodException will be thrown.
      Parameters:
      object - The instance which the method is invoked on
      methodName - The name of the method
      arguments - The arguments to the method
      Returns:
      The return value of the method which is null if the return type is void
      See Also:

    • invokeMethod

      Object invokeMethod(Object object, String methodName, Object arguments)
      Invokes a method on the given object, with the given name and single argument.
      Parameters:
      object - The Object to invoke the method on
      methodName - The name of the method
      arguments - The argument to the method
      Returns:
      The return value of the method which is null if the return type is void
      See Also:

    • invokeStaticMethod

      Object invokeStaticMethod(Object object, String methodName, Object[] arguments)
      Invokes a static method on the given Object with the given name and arguments.

      The Object can either be an instance of the class that this MetaObjectProtocol instance applies to or the java.lang.Class instance itself. If a method cannot be invoked a MissingMethodException is will be thrown

      Parameters:
      object - An instance of the class returned by the getTheClass() method or the class itself
      methodName - The name of the method
      arguments - The arguments to the method
      Returns:
      The return value of the method which is null if the return type is void
      See Also:

    • getProperty

      Object getProperty(Object object, String property)
      Retrieves a property of an instance of the class returned by the getTheClass() method.

      What this means is largely down to the MetaClass implementation, however the default case would result in an attempt to invoke a JavaBean getter, or if no such getter exists a public field of the instance.

      Parameters:
      object - An instance of the class returned by the getTheClass() method
      property - The name of the property to retrieve the value for
      Returns:
      The properties value
      See Also:

    • setProperty

      void setProperty(Object object, String property, Object newValue)
      Sets a property of an instance of the class returned by the getTheClass() method.

      What this means is largely down to the MetaClass implementation, however the default case would result in an attempt to invoke a JavaBean setter, or if no such setter exists to set a public field of the instance.

      Parameters:
      object - An instance of the class returned by the getTheClass() method
      property - The name of the property to set
      newValue - The new value of the property
      See Also:

    • getAttribute

      Object getAttribute(Object object, String attribute)
      Retrieves an attribute of an instance of the class returned by the getTheClass() method.

      What this means is largely down to the MetaClass implementation, however the default case would result in attempt to read a field of the instance.

      Parameters:
      object - An instance of the class returned by the getTheClass() method
      attribute - The name of the attribute to retrieve the value for
      Returns:
      The attribute value
      See Also:

    • setAttribute

      void setAttribute(Object object, String attribute, Object newValue)
      Sets an attribute of an instance of the class returned by the getTheClass() method.

      What this means is largely down to the MetaClass implementation, however the default case would result in an attempt to set a field of the instance.

      Parameters:
      object - An instance of the class returned by the getTheClass() method
      attribute - The name of the attribute to set
      newValue - The new value of the attribute
      See Also: