181 lines
6.4 KiB
Groff
181 lines
6.4 KiB
Groff
.\" $NetBSD: prop_ingest.3,v 1.6 2010/02/18 14:00:39 wiz Exp $
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.\"
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.\" Copyright (c) 2006 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Jason R. Thorpe.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd January 21, 2008
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.Dt PROP_INGEST 3
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.Os
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.Sh NAME
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.Nm prop_ingest_context_alloc ,
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.Nm prop_ingest_context_free ,
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.Nm prop_ingest_context_error ,
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.Nm prop_ingest_context_type ,
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.Nm prop_ingest_context_key ,
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.Nm prop_ingest_context_private ,
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.Nm prop_dictionary_ingest
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.Nd Ingest a dictionary into an arbitrary binary format
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.Sh SYNOPSIS
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.In prop/proplib.h
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.Ft prop_ingest_context_t
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.Fn prop_ingest_context_alloc "void *private"
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.Ft void
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.Fn prop_ingest_context_free "prop_ingest_context_t ctx"
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.Ft prop_ingest_error_t
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.Fn prop_ingest_context_error "prop_ingest_context_t ctx"
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.Ft prop_type_t
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.Fn prop_ingest_context_type "prop_ingest_context_t ctx"
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.Ft const char *
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.Fn prop_ingest_context_key "prop_ingest_context_t ctx"
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.Ft void *
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.Fn prop_ingest_context_private "prop_ingest_context_t ctx"
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.Ft bool
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.Fn prop_dictionary_ingest "prop_dictionary_t dict" \
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"const prop_ingest_table_entry rules[]" \
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"prop_ingest_context_t ctx"
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.Pp
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.Ft typedef bool
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.Fn (*prop_ingest_handler_t) "prop_ingest_context_t" "prop_object_t"
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.Sh DESCRIPTION
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The
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.Nm prop_dictionary_ingest
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function provides a convenient way to convert a property list into
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an arbitrary binary format or to extract values from dictionaries in a
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way that is convenient to an application
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.Pq for configuration files, for example .
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.Pp
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.Nm prop_dictionary_ingest
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is driven by a table of rules provided by the application.
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Each rule consists of three items:
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.Bl -bullet
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.It
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A C string containing a key to be looked up in the dictionary.
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.It
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The expected property type of the object associated with the key
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(or
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.Dv PROP_TYPE_UNKNOWN
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to specify that any type is allowed).
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.It
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A callback function of type
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.Dv prop_ingest_handler_t
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that will perform the translation for the application.
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.El
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.Pp
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The table is constructed using a series of macros as follows:
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.Bd -literal
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static const prop_ingest_table_entry ingest_rules[] = {
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PROP_INGEST("file-name", PROP_TYPE_STRING, ingest_filename),
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PROP_INGEST("count", PROP_TYPE_NUMBER, ingest_count),
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PROP_INGEST_OPTIONAL("required", PROP_TYPE_BOOL, ingest_required),
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PROP_INGEST_OPTIONAL("extra", PROP_TYPE_UNKNOWN, ingest_extra),
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PROP_INGEST_END
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};
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.Ed
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.Pp
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The
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.Dv PROP_INGEST
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macro specifies that the key is required to be present in the dictionary.
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The
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.Dv PROP_INGEST_OPTIONAL
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macro specifies that the presence of the key in the dictionary is optional.
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The
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.Dv PROP_INGEST_END
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macro marks the end of the rules table.
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.Pp
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In each case,
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.Nm prop_dictionary_ingest
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looks up the rule's key in the dictionary.
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If an object is present in the dictionary at that key, its type is checked
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against the type specified in the rule.
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A type specification of
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.Dv PROP_TYPE_UNKNOWN
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allows the object to be of any type.
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If the object does not exist and the rule is not marked as optional, then
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an error is returned.
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Otherwise, the handler specified in the rule is invoked with the ingest
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context and the object
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(or
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.Dv NULL
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if the key does not exist in the dictionary).
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The handler should return
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.Dv false
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if the value of the object is invalid to indicate failure and
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.Dv true
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otherwise.
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.Pp
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The ingest context contains several pieces of information that are
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useful during the ingest process.
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The context also provides specific error information should the ingest
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fail.
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.Bl -tag -width "xxxxx"
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.It Fn prop_ingest_context_alloc "void *private"
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Allocate an ingest context.
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The argument
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.Fa private
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may be used to pass application-specific context to the ingest handlers.
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Note that an ingest context can be re-used to perform multiple ingests.
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Returns
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.Dv NULL
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on failure.
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.It Fn prop_ingest_context_free "prop_ingest_context_t ctx"
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Free an ingest context.
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.It Fn prop_ingest_context_error "prop_ingest_context_t ctx"
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Returns the code indicating the error encountered during ingest.
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The following error codes are defined:
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.Pp
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.Bl -tag -width "PROP_INGEST_ERROR_HANDLER_FAILED" -compact
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.It Dv PROP_INGEST_ERROR_NO_ERROR
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No error was encountered during ingest.
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.It Dv PROP_INGEST_ERROR_NO_KEY
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A non-optional key was not found in the dictionary.
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.It Dv PROP_INGEST_ERROR_WRONG_TYPE
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An object in the dictionary was not the same type specified in the rules.
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.It Dv PROP_INGEST_ERROR_HANDLER_FAILED
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An object's handler returned
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.Dv false .
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.El
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.Pp
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.It Fn prop_ingest_context_type "prop_ingest_context_t ctx"
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Returns the type of the last object visited during an ingest.
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When called by an ingest handler, it returns the type of the object
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currently being processed.
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.It Fn prop_ingest_context_key "prop_ingest_context_t ctx"
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Returns the last dictionary key looked up during an ingest.
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When called by an ingest handler, it returns the dictionary key corresponding
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to the object currently being processed.
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.It Fn prop_ingest_context_private "prop_ingest_context_t ctx"
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Returns the private data set when the context was allocated with
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.Fn prop_ingest_context_alloc .
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.El
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.Sh SEE ALSO
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.Xr prop_dictionary 3 ,
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.Xr proplib 3
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.Sh HISTORY
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The
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.Nm proplib
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property container object library first appeared in
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.Nx 4.0 .
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