Class Reference
%Library.AbstractStream
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Private Storage |
Deprecated class, the base stream class is
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 Caché streams are used to create large (greater than 32K) object attributes.
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%Location | AtEnd | Attributes | Id | LastModified |
LineTerminator | Size |
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The maximum number of characters (or bytes) allowed in a stream.
Turns off property validation.
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An array of strings containing any attribute values associated with this stream.
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'.
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Returns the persistent object Id, if there is one, of this object.Returns a null string if there is no object Id.
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.
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).
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 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 callClear on the stream object.
Flush any output in the stream not already saved.
Retrieves the named attribute value
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
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 Caché ODBC server.
This is a Set accessor method for theLineTerminator property.
Move to the end of the stream so the nextWrite 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
Reads 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 andRead will return a null string ("").You must call
Rewind if you want to read a stream from the beginning again. CallingRead afterWrite implicitly ends theWrite 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.
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 ! } }
This reads from the stream until it find theLineTerminator and returns this as a stream. If the stream does not contain the line terminator this can potentially be the entire stream.
Go back to the start of the stream.
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
This is a Get accessor method for theSize property.
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.
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.