%Library.AbstractStream
deprecated abstract stream class %Library.AbstractStream extends %Stream.Object
Deprecated class, the base stream class is %Stream.Object. This is kept for legacy reasons.A stream represents an arbitrary array of characters (or bytes) and a current position. The basic stream interface provides the ability to read data from a stream, write data to the stream, and rewind the current position to the beginning of the stream.
Within InterSystems IRIS streams are used to create large (greater than 32K) object attributes.
Property Inventory
Method Inventory
- %Id()
- %IsModified()
- %IsNull()
- %ObjectModified()
- CopyFrom()
- DeleteAttribute()
- DeleteStream()
- Flush()
- GetAttribute()
- GetAttributeList()
- GetStreamId()
- IsDefinedAttribute()
- IsNull()
- LineTerminatorSet()
- MoveToEnd()
- NextAttribute()
- OpenStream()
- Read()
- ReadLine()
- ReadLineIntoStream()
- Rewind()
- SaveStream()
- SetAttribute()
- SetAttributeList()
- SizeGet()
- Write()
- WriteLine()
Parameters
parameter MAXLEN = 2147483647;
The maximum number of characters (or bytes) allowed in a stream.
parameter MAXLOCALSIZE = 32000;
parameter PROPERTYVALIDATION = 0;
Turns off property validation.
final parameter READCHANGED = 2;
final parameter READNODATA = 0;
final parameter READNOTCHANGED = 1;
final parameter WRITE = 3;
Properties
property Attributes as %String [ MultiDimensional ];
An array of strings containing any attribute values associated with this stream.
Property methods: AttributesDisplayToLogical(), AttributesGet(), AttributesIsValid(), AttributesLogicalToDisplay(), AttributesLogicalToOdbc(), AttributesNormalize(), AttributesSet()
property LineTerminator as %String (MAXLEN = 10) [ InitialExpression = $char(13,10) ];
Type of line terminator we use for this stream, defaults to Cr/Lf. Maximum length is 10 characters.
This is stored as an attribute of the stream called 'LineTerminator'.
Property methods: LineTerminatorDisplayToLogical(), LineTerminatorGet(), LineTerminatorIsValid(), LineTerminatorLogicalToDisplay(), LineTerminatorLogicalToOdbc(), LineTerminatorNormalize()
Methods
method %Id() as %String
Returns the persistent object Id, if there is one, of this object.
Returns a null string if there is no object Id.
method %IsModified() as %Integer
Inherited description: Returns true (1) if a property of this instance has been modified, otherwise false (0).
A TRUE result does not necessarily mean that any property has actually been changed. If
%IsModified() returns false then the object has not been modified. There are some
situations where we simply cannot efficiently detect a change in value. In these cases we
will set the modified status of the property.
method %IsNull() as %Boolean
Returns true if this is a "NULL" stream; that is, a stream which has never
been written to and saved. This is used by the InterSystems IRIS ODBC server.
method %ObjectModified() as %Integer
Inherited description: This method is somewhat similar to %IsModified but it also checks to see if swizzled
references would cause the object to become modified should they be serialized. This works
on the assumption that a reference to a persistent object will never be modified if the ID has
already been assigned. For references to serial objects, a call to %ObjectModified indicates
whether or not the serialized value is different. If the reference to a swizzled object is
different from the initial object state then the $$$objModAll macro will already return true.
Reference the Set code.
Returns true (1) if this instance has been modified, otherwise false (0).
method CopyFrom(source As %Stream.Object) as %Status
Copies the contents of source into this Stream.
For example, you can copy oldstream into a new stream:
Set newstream=##class(%GlobalCharacterStream).%New() Do newstream.CopyFrom(oldstream)
Returns a %Status value indicating success or failure.
Removes this attribute variable from the collection. Returns true is it existed and false if it
did not exist.
deprecated classmethod DeleteStream(oid As %ObjectIdentity, concurrency As %Integer = 0) as %Status
Deprecated method, use %Delete() instead.
Deletes the stored stream identified by oid. This will not remove the stream attributes of any
saved streams, it will just remove the stream data. If you need to clear the attributes as well you will
have to call Clear() on the stream object.
method Flush() as %Status
Inherited description: Flush any output in the stream not already saved.
Retrieves the named attribute value
method GetAttributeList() as %String
method GetStreamId() as %String
Returns an full id value (including class name) with which the Stream implementation has stored
the stream.
Returns true if the named attribute variable exists in the collection, false otherwise
method IsNull() as %Boolean
Returns true if this is a "NULL" stream; that is, a stream which has never
been written to and saved. This is used by the InterSystems IRIS ODBC server.
method MoveToEnd() as %Status
Inherited description: Move to the end of the stream so the next Write() will be appended to the end.
This allows you to read from a stream, then MoveToEnd() and append new data, where just calling
Write() after a read will clear the stream before writing new data.
Returns a %Status value indicating success or failure.
Retrieves the next attribute variable name in the sequence, skip any '%' names
method Read(ByRef len As %Integer = 32656, ByRef sc As %Status) as %RawString
Inherited description: Read up to len characters from the current position
in the stream. The current position is advanced by the number of
characters read. Upon exit, len is set to the actual
number of characters read. If a read occurs when the stream position
is at the end of the stream, len will be set to -1 and
Read() will return a null string (""). If no len
is passed in, ie. 'Read()' then it is up to the Read implementation as to
how much data to return. Some stream classes use this to optimize the amount of
data returned to align this with the underlying storage of the stream.
You must call Rewind() if you want to read a stream from the beginning again. Calling Read() after Write() implicitly ends the Write() operation and rewinds to the start of the stream.
Returns a string up to len characters long. The byref argument sc will return a %Status if any error occurred during the read.
method ReadLine(ByRef len As %Integer = 32000, ByRef sc As %Status, ByRef eol As %Boolean) as %RawString
Inherited description: Read a line from the stream. This will look for the line terminator in the stream and
once it finds the terminator it will return the string minus the terminator character/s. If it reaches the
end of the stream before it finds a terminator it will return the data it has so far, and if you specify a
maximum size in len it will only read up to this number of characters. On exit len
will contain the actual number of characters read. The byref argument sc will
return a %Status() if any error occured during the read and the byref argument eol
is true if it found the line terminator and false otherwise. So for example you can read in a stream
a line at a time and output the results to the current device with:
While 'stream.AtEnd { Write stream.ReadLine(,.sc,.eol) If $$$ISERR(sc) { Write "ERROR" Quit } If eol { Write ! } }
method ReadLineIntoStream(ByRef sc As %Library.Status) as %AbstractStream
This reads from the stream until it find the LineTerminator and returns
this as a stream. If the stream does not contain the line terminator this can potentially be the
entire stream.
method Rewind() as %Status
Inherited description: Go back to the start of the stream.
deprecated method SaveStream() as %Status
Deprecated method, use %Save() instead.
Saves the temporary copy of the stream data to a persistent location. Note that
any locking or transaction handling must be done by the caller.
Returns a %Status value indicating success or failure.
Inserts an attribute variable by name into the collection
method SetAttributeList(attr As %String)
method SizeGet() as %Integer
method Write(data As %RawString = "") as %Status
Inherited description: Appends the string data to the stream and advances the
current stream position by the number of characters in data.
Note that a write operation immediately following a read or rewind will clear out the existing data in the stream.
Returns a %Status value indicating success or failure.
method WriteLine(data As %RawString = "") as %Status
Appends the string data along with a line terminator to the stream and advances the
current stream position by the number of characters in data plus the line terminator.
Returns a %Status value indicating success or failure.
Inherited Members
Inherited Properties
Inherited Methods
- %AddToSaveSet()
- %CheckUnique()
- %ClassIsLatestVersion()
- %ClassName()
- %ConstructClone()
- %Delete()
- %DeleteExtent()
- %DeleteId()
- %DispatchClassMethod()
- %DispatchGetModified()
- %DispatchGetProperty()
- %DispatchMethod()
- %DispatchSetModified()
- %DispatchSetMultidimProperty()
- %DispatchSetProperty()
- %Exists()
- %ExistsId()
- %Extends()
- %GetParameter()
- %GetSwizzleObject()
- %IsA()
- %KillExtent()
- %LOBPrefetch()
- %LocationSet()
- %LockStream()
- %New()
- %NormalizeObject()
- %ObjectIsNull()
- %ObjectSize()
- %Oid()
- %Open()
- %OpenId()
- %OriginalNamespace()
- %PackageName()
- %ReleaseLock()
- %Reload()
- %RemoveFromSaveSet()
- %RollBack()
- %Save()
- %SerializeObject()
- %SetModified()
- %UnlockStream()
- %ValidateObject()
- Clear()
- CopyFromAndSave()
- FindAt()
- InputFromDevice()
- IsCharacter()
- LastModifiedGet()
- MoveTo()
- OutputToDevice()
- OutputToDeviceAt()
- ReadSQL()
- SerializeToSyncSet()
- StreamOIDIsNull()
- SyncStreamIn()