{HISTORY of BTP - the Btrieve Unit for Turbo Pascal 6.0 V1.5, 11/9/91 } (* ----------------------------------------------------------------------- *) Version 1.0 4/9/91: Initial functioning unit, released 9/5/91. Version 1.1 9/8/91: Corrected a problem occuring in Btrieve files that had segmented keys with more than one segment. The stats stored by the BFile.Init constructor were not calculating the number of segments properly. The CreateFile function was also modified to deal with the same key problem. This change forces one more statement to be placed in any 'create file' routine. Any of the 24 key arrays not used in a file must have their key flags set to zero. See Create.PAS for an example. Version 1.2 9/16/91: NOT RELEASED PUBLICLY. Derived a new base object, BRecMgr, from what HAD been my base object, BFile. It made sense to me to provide access directly thru an object to the basic, non-file, non-record oriented Btrieve operations: Begin/End/Abort Transaction, Version, Stop and Reset. This BLOWS compatibility with any code you wrote under prior versions of this unit as the BT function is now virtual. You should NOT call the ancestor BT function in your override...replace it completely as shown in the example programs and in BTP.DOC. BRecMgr has a variant record field to hold info on the version of Btrieve the user is running. That data is set by BRecMgr.Init. Version 1.3 10/11/91: Unit name changed to BTP. Bug fixed that would give incorrect result in BFile.NumRecs if number of records exceeded 32,767. Made a number of "touch-up" changes to make it easier to use dynamic variables of the various data types in BTP. Note particularly that the CreateFile function now requires a second parameter, a pointer to a Btrieve file spec as defined in BTP. The constructors for BRecMgr and BFile now set up a string data field, VersionString, equal to the version number of Btrieve running in the user's computer. This is in addition to establishing the record field Version, which contains the exact bytes returned by the Btrieve version call. All example programs were modified to reflect the changes in 1.2 and 1.3. Version 1.4 10/27/91: Nomenclature of data types improved and made more consistent, both within BTP and with TP6's own internal Turbo Vision style. TRecMgr and BFile are now separate "base" objects. Added BFixed and BFileExt objects, both descendants of BFile. Together these permit handling any standard fixed-length file, and provide complete support for the get/step extended calls, including handling of all the drudgery of constructing data buffers. This was no small task! For extended calls, you need simply insert your filter and extractor specs into the provided collections in BFileExt. The rest of the setup is transparent to you, being handled by the object's internal methods and your standard override of the BTExt function. An object of type BFileExt can freely entertain both standard BT and extended BTExt calls thanks to encapsulation of the position block in the object (see EXAMPLE2.PAS). However, I recommend use of BFileExt only if you are truly going to use extended calls for a particular file. This is because there is about 32K more overhead per BFileExt object than BFile. The size of a BFile object is 698 bytes. The size of a BFileExt object is 722 bytes, plus the size of the extended data buffer, which I default to 32767 bytes, plus the size of any items inserted into the two collections. Note that the size of a BFixed object is 5043 bytes, to hold room for a buffer equal to the maximum size of a fixed length record, and the maximum length of a key. BFile and its descendants now take an Open mode parameter. The BFile.BT virtual function is now Abstract, to assure you don't call it without overriding it. The BFileExt.BTExt method must be overridden, with the override calling the ancestor; i.e. your override must be of a standard form, and must call BFileExt.BTExt. This is because BFileExt.BTExt is what sets the buffer length and constructs the buffer for extended read calls. This is in contrast to BFile.BT or BFileExt.BT, which must be overridden by REPLACING them, as shown in the example programs and in BTP.DOC. BFileExt's data fields include two collections. The FilterSpec collection need not hold any objects, but the ExtractorSpec must always hold at least one. Now, for extended calls, you handle these data fields as follows (see EXAMPLE2.PAS): 1: HEADER is handled internally. Don't mess with it. 2: FILTER's fields are assigned by your program. 3: FILTERSPEC collection may or may not hold any objects, depending on your program's needs. 4: EXTRACTOR must be initialized. 5: EXTRACTORSPEC collection must hold at least one object. 6: EXTDBUFFER is handled internally. Don't mess with it, except to use it as shown in EXAMPLE2.PAS when you override BFileExt.BTExt. BTP 1.4 IS THE FIRST *SHAREWARE* RELEASE. The BTP product is no longer FreeWare. Version 1.5 11/9/91: New in this release...complete support for alternate collating sequences. This required modifying the BFile object and its constructor, and the CreateFile function, and the addition of data structures for an alternate collating sequence file. A boolean field in BFile, HasAltCol, has been established. The CreateFile function now takes a third parameter, being the name of an alternate collating sequence file, if any. Also changed in this version: BFile has an additional field for a file's actual filespec length. This can be useful when cloning a file. A new function, CloneFile, has been added, which reduces the cloning process to a single function call, with only the names of the existing and new files passed as parameters. Miscellaneous changes in V1.5 include elimination of a redundant parameter previously required by the FilterSpec object's constructors. Added a variant to both the FileSpec and KeySpec objects to allow easier reporting of certain stats after a stat call. Some minor optimizations done here and there thruout the unit and example programs. BEST NEWS! The STATS program has been greatly enhanced. It now produces substantially the same output as 'BUTIL -STAT', but is a standalone program and can be freely distributed with your applications (unlike BUTIL) IF YOU ARE A REGISTERED USER of BTP.