EiffelBase class
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Eiffel Class
indexing
description: "Objects that may be stored and retrieved along with all their dependents. This class may be used as ancestor by classes needing its facilities.";
status: "See notice at end of class";
date: "$Date: 2007-03-30 19:10:11 +0000 (Fri, 30 Mar 2007) $";
revision: "$Revision: 95354 $"
class STORABLE
inherit
EXCEPTIONS
feature -- Access
retrieved (medium: IO_MEDIUM): ANY is
-- Retrieved object structure, from external
-- representation previously stored in medium.
-- To access resulting object under correct type,
-- use assignment attempt.
-- Will raise an exception (code Retrieve_exception)
-- if medium content is not a stored Eiffel structure.
require
medium_not_void: medium /= void;
medium_exists: medium.exists;
medium_is_open_read: medium.is_open_read;
medium_supports_storable: medium.support_storable
do
Result := medium.retrieved
ensure
result_exists: Result /= void
end;
retrieve_by_name (file_name: STRING): ANY is
-- Retrieve object structure, from external
-- representation previously stored in a file
-- called file_name.
-- To access resulting object under correct type,
-- use assignment attempt.
-- Will raise an exception (code Retrieve_exception)
-- if file content is not a stored Eiffel structure.
-- Will return Void if the file does not exist or
-- is not readable.
require
file_name_exists: file_name /= void;
file_name_meaningful: notfile_name.empty
local
file: RAW_FILE
do
create file.make (file_name);
if file.exists and then file.is_readable then
file.open_read;
Result := file.retrieved;
file.close
end
end;
feature -- Element change
basic_store (medium: IO_MEDIUM) is
-- Produce on medium an external representation of the
-- entire object structure reachable from current object.
-- Retrievable within current system only.
require
medium_not_void: medium /= void;
medium_exists: medium.exists;
medium_is_open_write: medium.is_open_write;
medium_supports_storable: medium.support_storable
do
medium.basic_store (Current)
end;
general_store (medium: IO_MEDIUM) is
-- Produce on medium an external representation of the
-- entire object structure reachable from current object.
-- Retrievable from other systems for same platform
-- (machine architecture).
require
medium_not_void: medium /= void;
medium_exists: medium.exists;
medium_is_open_write: medium.is_open_write;
medium_supports_storable: medium.support_storable
do
medium.general_store (Current)
end;
independent_store (medium: IO_MEDIUM) is
-- Produce on medium an external representation of the
-- entire object structure reachable from current object.
-- Retrievable from other systems for the same or other
-- platform (machine architecture).
require
medium_not_void: medium /= void;
medium_exists: medium.exists;
medium_is_open_write: medium.is_open_write;
medium_supports_storable: medium.support_storable
do
medium.independent_store (Current)
end;
store_by_name (file_name: STRING) is
-- Produce on file called file_name an external
-- representation of the entire object structure
-- reachable from current object.
-- Retrievable from other systems for same platform
-- (machine architecture).
require
file_name_not_void: file_name /= void;
file_name_meaningful: notfile_name.empty
local
file: RAW_FILE;
a: ANY
do
create file.make (file_name);
if (file.exists and then file.is_writable) or else (file.is_creatable) then
file.open_write;
file.general_store (Current);
file.close
else
a := ("write permission failure").to_c;
eraise ($a, io_exception)
end
end;
end -- class STORABLE
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