Stream Classes

Class File Stream

The File Stream class provides I/O to a file system. In this documentation, the term directory is synonymous with "folder" in Windows.

All the functions provided in the Abstract Stream class can be used, and these additional functions:

Enum OpenModes Inherits Modes {
	Overwrite = 256,
	Append = 512 | Output,
};

Function Open (FileName: String @ "For" Mode: OpenModes);

This function attempts to open a file. If the open fails, an exception is thrown.

FileName --> the drive, path and filename of the file to open. If the drive is omitted on DOS/Windows systems, the current drive is assumed. If no path is provided, or if a relative path is given, the current directory for the thread is used as a base. Slashes and backslashes (/, \) are recognized as path separators on all implementations.

Mode: Mode in which to open the file. Multiple modes can be combined using the bitwise OR operator (|). The modes are as follows:

• Input: Requests read access to the file. Unless Output is also present, the file must exist to be opened.
• Output: Requests write access to the file. If the file does not exist, it is created.
• Append: This flag includes the Output flag, and means that all output will be to the end of file. A file opened in this mode cannot write anywhere but the end of the file; seek operations can apply only to the read pointer. If you want to append data to a file but allow write- seek, you must open the file for Output, then move to the end of the file with SetWritePos.
• Text: This flag enables text-file translations.
  On Windows systems, all newline characters ('\n') that are output are translated to a cr-lf combination ('\r', '\n'); on read, these two characters are translated to a single newline character.
• Overwrite: This flag takes effect only when the Output flag is specified; it means that, if the file being opened already exists, it should be truncated to zero size.  Cannot be used with WriteSeek.
• WriteSeek: This flag enables the stream's write pointer to be changed at will.  This flag is ignored if Output access is not used.
• ReadSeek: This flag enables the stream's read pointer to be changed.  This flag is ignored if Input access is not used.

Note: On some systems, the file may be opened with more capabilities than requested.

The ReadPos and WritePos flags have no effect when opening files.  Any file that is opened for Input will be able to retrieve the read pointer; and file that is opened for output will be able to retrieve the write pointer.

Function Close () Returns Boolean;

This function closes the currently opened file. True is returned on success, False on failure. The function can fail only if no file is open.

Function Destructor ();

This function closes the file if it is open.

Class Memory Stream

The Memory Stream class allows data serialization to a block of memory. Uses of this class include data transfer between processes, or through the clipboard.

Function Create (Preallocate: Integer(0); GrowBy: Integer(64));

This function creates a block of memory for reading or writing and attaches itself to it. Preallocate specifies the amount of memory to allocate initially, while GrowBy specifies the granularity by which to increase the size of the block(s) containing the memory file. If the memory allocation fails, a ??? exception will be thrown. If the object is already attached to a block of memory, ??? exception is thrown.

Function Attach (ToRead: @; Size: Integer);

Associates the Memory File object with an existing block of memory, the size of which is specified by Size (in bytes).

If the Memory File is already attached to a memory block, a ??? exception will be thrown.

The Memory File object cannot write past the end of the block because it cannot reallocate the block (since it does not own the memory or know anything about it.) Attempting to write past the end of an attached block will cause a ??? exception to be thrown.

Function Close() Returns Boolean;

This function closes the memory file. If the file was created with Create, the memory block is freed; otherwise the object just "forgets about" the memory block with which it is associated. If the file is closed already, the function returns False; otherwise it returns True.

Class Config Stream

Class Pipe Stream

Class Standard In

Class Standard Out