BDataSet - Project Management

File: BDataSet.STX, linked to library STX.LIB

See also:

This class implements the XML Project document. The Project document is the global database available to all STx applications and scripts and contains all data and links of the current project. The programmer must not create or destroy the project object because these functions are performed by the application startup and cleanup macros.

At application startup a BDATASET instance is created and linked to the global Project document which is created and managed by the STx master shell and/or the application Project. The name of this instance is stored in the shell variable BDATASET. This object must be used to access the project document.

Never ever call the member functions CONSTRUCT, DESTRUCT or CLOSE!

If the project content is changed by a command (or during a block of commands), or if a longer operation is performed on the project, the ATTACH and DETACH functions should be called:

$bdataset ATTACH

 // ...project commands...

$bdataset DETACH

No static commands are implemented; a call to the macro BDataSet (e.g. bdataset save) will do nothing, returning an empty string.

The class BDataSet is derived from the class BXMLDoc.

Beware of using the base class functions, since they do not update the BDataSet member variables!

Attach/Detach

The function ATTACH locks the project document and returns the internal xml-file item containing the project data. Only the calling shell can now access the project content, all other shells are blocked. The project document remains locked until the next call to DETACH.

Multiple calls of ATTACH (by the same shell) are possible, but for each call of ATTACH also the function DETACHmust be called.

// example for using ATTACH / DETACH
// first attach call - lock project document and save current xml-position (pos1)
#projectFileItem := $bdataset attach
... 
//	second attach call - save xml-position (pos2)
...
// first detach call - restore xml-position pos2
...
//	second detach call - restore xml-position and unlock project document, 
//	if the project document was changed by the code between first attach and second detach,
// the message "DATASETCHANGED" is sent to all running shells