edu.vub.at.objects.natives
Class NATNamespace

java.lang.Object
  edu.vub.at.objects.natives.NATNil
      edu.vub.at.objects.natives.NATByRef
          edu.vub.at.objects.natives.NATCallframe
              edu.vub.at.objects.natives.NATObject
                  edu.vub.at.objects.natives.NATNamespace

All Implemented Interfaces:

ATAbstractGrammar, ATConversions, ATExpression, ATNil, ATObject, ATStatement, java.io.Serializable

public final class NATNamespace

extends NATObject

Instances of the class NATNamespace represent namespace objects. Namespace objects act as regular AmbientTalk objects with the following differences and conventions: - Behaviourally, a namespace object is mirrored by a mirror whose doesNotUnderstand method reacts differently from the standard semantics of raising a 'selector not found' exception. - Structurally, a namespace has the lexical root as its lexical parent and the dynamic root as its dynamic parent. Furthermore, a namespace object encapsulates an absolute file system path and a relative 'path name'. The name should correspond to a portion of the tail of the absolute path. These variables are not visible to AmbientTalk code. When a slot is looked up in a namespace NS for a path P (via meta_select) and not found, the namespace object queries the local file system to see whether the selector corresponds to a directory or file in the directory P. Either the selector: - corresponds to a directory, in which case the missing slot is bound to a new namespace object corresponding to the path P/selector - corresponds to a file named selector.at, in which case: 1) the slot is temporarily bound to nil (this is to prevent loops when the code to be evaluated would refer to itself; it also means there can be no circular dependencies, because referring to a slot still under construction yields nil) 2) a new object FS (the 'file scope') is created. This object acts as the local scope for the file and has access to its 'enclosing' namespace via the '~' slot. Hence, it can refer to other files in the 'current directory' using ~.filename 3) the code in the file is loaded and evaluated in the context (current=FS, self=FS, super=FS.parent=dynroot) 4) the result of the evaluated code is bound to the missing slot. The next time the slot is queried for in the namespace, the value is immediately returned. This prevents files from being loaded twice. - does not correspond to any file or directory, resulting in a selector not found exception as usual.

Author:

tvcutsem, smostinc

See Also:

Serialized Form

Field Summary

private static java.lang.String	_AT_EXT_
private java.lang.String	name_
private java.io.File	path_

Fields inherited from class edu.vub.at.objects.natives.NATObject

_EQL_NAME_, _INI_NAME_, _IS_A_, _NEW_NAME_, _NO_STRIPES_, _SHARES_A_, _SUPER_NAME_, stripes_

Fields inherited from class edu.vub.at.objects.natives.NATCallframe

customFields_, lexicalParent_, stateVector_, variableMap_

Fields inherited from class edu.vub.at.objects.natives.NATNil

_INSTANCE_

Constructor Summary

private	NATNamespace(FieldMap map, java.util.Vector state, java.util.LinkedList customFields, MethodDictionary methodDict, ATObject dynamicParent, ATObject lexicalParent, byte flags, ATStripe[] stripes, java.io.File path, java.lang.String name) Private constructor used only for cloning
	NATNamespace(java.lang.String name, java.io.File path) A namespace object encapsulates a given absolute path and represents the given relative path.

Method Summary

protected NATObject	createClone(FieldMap map, java.util.Vector state, java.util.LinkedList customFields, MethodDictionary methodDict, ATObject dynamicParent, ATObject lexicalParent, byte flags, ATStripe[] stripes)
static NATObject	createFileScopeFor(NATNamespace ns)
ATObject	meta_doesNotUnderstand(ATSymbol selector) For a namespace object, doesNotUnderstand triggers the querying of the local file system to load files corresponding to the missing selector.
NATText	meta_print() Prints out the object in a human-readable way.

Methods inherited from class edu.vub.at.objects.natives.NATObject

asAmbientTalkObject, base_asActorMirror, base_asAsyncMessage, base_asBegin, base_asBoolean, base_asClosure, base_asDefinition, base_asExpression, base_asField, base_asHandler, base_asMessage, base_asMessageCreation, base_asMethod, base_asMirror, base_asNumber, base_asSplice, base_asStatement, base_asStripe, base_asSymbol, base_asTable, base_asUnquoteSplice, base_isBoolean, base_isCallFrame, base_isClosure, base_isMethod, base_isMirror, base_isSplice, base_isStripe, base_isSymbol, base_isTable, base_isUnquoteSplice, createChild, createIsolate, isAmbientTalkObject, isPrimitive, listTransitiveFields, listTransitiveMethods, meta_addMethod, meta_assignField, meta_clone, meta_defineField, meta_extend, meta_getStripes, meta_grabMethod, meta_invoke, meta_isCloneOf, meta_isRelatedTo, meta_isStripedWith, meta_listMethods, meta_lookup, meta_newInstance, meta_pass, meta_resolve, meta_respondsTo, meta_select, meta_share

Methods inherited from class edu.vub.at.objects.natives.NATCallframe

getLocalCustomField, getLocalField, hasLocalCustomField, hasLocalField, hasLocalNativeField, meta_addField, meta_assignVariable, meta_getDynamicParent, meta_getLexicalParent, meta_grabField, meta_listFields, setLocalField

Methods inherited from class edu.vub.at.objects.natives.NATNil

asJavaClassUnderSymbiosis, asJavaObjectUnderSymbiosis, asNativeBoolean, asNativeException, asNativeFarReference, asNativeFraction, asNativeNumber, asNativeNumeric, asNativeTable, asNativeText, base__opeql__opeql_, base_asFarReference, base_asVariableAssignment, base_init, base_isFarReference, base_isMessageCreation, base_isVariableAssignment, base_new, equals, isJavaObjectUnderSymbiosis, isNativeBoolean, isNativeField, isNativeText, meta_eval, meta_quote, meta_receive, meta_send, readResolve, toString, writeReplace

Methods inherited from class java.lang.Object

clone, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface edu.vub.at.objects.ATObject

base__opeql__opeql_, base_init, base_new, meta_addField, meta_assignVariable, meta_eval, meta_getDynamicParent, meta_getLexicalParent, meta_grabField, meta_listFields, meta_quote, meta_receive, meta_send

Methods inherited from interface edu.vub.at.objects.coercion.ATConversions

asJavaClassUnderSymbiosis, asJavaObjectUnderSymbiosis, asNativeBoolean, asNativeException, asNativeFarReference, asNativeFraction, asNativeNumber, asNativeNumeric, asNativeTable, asNativeText, base_asFarReference, base_asVariableAssignment, base_isFarReference, base_isMessageCreation, base_isVariableAssignment, isJavaObjectUnderSymbiosis, isNativeBoolean, isNativeField, isNativeText

Field Detail

_AT_EXT_

private static final java.lang.String _AT_EXT_

See Also:

Constant Field Values

path_

private final java.io.File path_

name_

private final java.lang.String name_

Constructor Detail

NATNamespace

public NATNamespace(java.lang.String name,
                    java.io.File path)

A namespace object encapsulates a given absolute path and represents the given relative path.

Parameters:

name - the name of this namespace (corresponding to a certain depth to the tail of the absolute path)

path - an absolute path referring to a local file system directory.

NATNamespace

private NATNamespace(FieldMap map,
                     java.util.Vector state,
                     java.util.LinkedList customFields,
                     MethodDictionary methodDict,
                     ATObject dynamicParent,
                     ATObject lexicalParent,
                     byte flags,
                     ATStripe[] stripes,
                     java.io.File path,
                     java.lang.String name)
              throws InterpreterException

Private constructor used only for cloning

Method Detail

meta_doesNotUnderstand

public ATObject meta_doesNotUnderstand(ATSymbol selector)
                                throws InterpreterException

For a namespace object, doesNotUnderstand triggers the querying of the local file system to load files corresponding to the missing selector.

Specified by:

meta_doesNotUnderstand in interface ATObject

Overrides:

meta_doesNotUnderstand in class NATCallframe

Throws:

InterpreterException

meta_print

public NATText meta_print()
                   throws InterpreterException

Description copied from interface: ATObject

Prints out the object in a human-readable way.

Specified by:

meta_print in interface ATObject

Overrides:

meta_print in class NATObject

Throws:

InterpreterException

createFileScopeFor

public static NATObject createFileScopeFor(NATNamespace ns)

createClone

protected NATObject createClone(FieldMap map,
                                java.util.Vector state,
                                java.util.LinkedList customFields,
                                MethodDictionary methodDict,
                                ATObject dynamicParent,
                                ATObject lexicalParent,
                                byte flags,
                                ATStripe[] stripes)
                         throws InterpreterException

Overrides:

createClone in class NATObject

Throws:

InterpreterException