From WHATSNEW.TXT:
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See below ("UPGRADING FROM 1.8.4") for important changes that may
affect you when upgrading from an earlier release - especially if
you use the c4_String class, or if you are using the MFC build.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -WHAT IS THIS RELEASE?
This new release is a minor release which offers substantial string search performance improvements, is much quicker in views with large numbers of properties, and offers a few new features, such as a new regular expression match for strings. The MFC I/O model was dropped, in favor of using stdio in all configurations (you can still get any type of I/O mechanism you like by overriding c4_Strategy, as before). Any of the 3 configurations (MFC, STL, or UNIV) can be used in any context, now that c4_String and c4_File are gone from the public API. Only two minor bug fixes: affecting c4_View's GroupBy and Project.
WHAT HAS HAPPENED RECENTLY?
There have been a few more ports, affecting the source in minor ways. The Tcl interface is now at revision 1.0.6, and is being used in a number of production-strength development projects and products. The Python interface has just been bumped to version 0.5, and though it appears quite stable, is still incomplete and a bit quirky to use.
WHAT HAS NOT HAPPENED?
The documentation has not been updated. The two undocumented changes are: all references to c4_String have been changed to "const char*", and: the c4_View::Match member does regexp matching (used like Find).
UPGRADING FROM 1.8.4:
This release makes some changes which are likely to affect your code.
For starters, the "c4_String" class is no longer available by default. If you use this class in your code, you'll need to include a header:
#include <mk4.h> #include <mk4str.h> // <-- this defines the c4_String class
Furthermore, the following example will no longer work in this release:
c4_View view = ...
c4_StringProp pName ("name");
const char* str = (c4_String) pName (view[123]);The fix is to get rid of the c4_String temporary:
const char* str = pName (view[123]);
Explanation: the API of Metakit has been changed to avoid *all* uses of c4_String (and CString in MFC). Instead, a small amount of internal buffering is used to be able to always return a "const char*" instead. (This change accounts for a whopping 2..3-fold performance increase!) The problem with the above code is the lifetime of c4_String objects.
Unfortunately, the above example is likely to not work either, because "str" now occasionaly points to a temporary buffer inside Metakit (the actual buffer depends on alignment - most of the time, str will just point directly into the memory mapped file). The "correct" solution is to allocate your own temporary buffer, as follows:
c4_String temp = pName (view[123]); const char* str = temp;
Now, "str" will be correct as long as temp is valid / in scope.
******************************************************************** ** STRINGS RETURNED BY METAKIT ARE NOW ONLY GUARANTEED TO REMAIN ** ** VALID UNTIL THE NEXT CALL OF *ANY* FUNCTION IN THE METAKIT API ** ********************************************************************
Another major change, is that the MFC configuration now uses stdio for datafile I/O, instead of MFC's CFile class. Since stdio does not offer a portable way to implement access control, nor system-level flushing, nor file truncation, this has a number of consequences:
- Opening a datafile for writing will no longer prevent other readers/writers from opening the file as well. If you used to rely on this, you will need to make sure shared access does not happen (any open for write of the file makes all other accesses illegal, and can lead to file corruption. - Flushing used to call the Windows system flush as part of the c4_Strategy::DataCommit call, to make sure data was really on disk before a commit returns. The effect of this is that true "stable storage" is achieved, which is able to recover, even from power failure at any point in the commit sequence. Without such flushing, there are a few seconds during which the state on disk does not exactly reflect the commited state. Chances of problems are still minute (only an immediately following commit could get into trouble), but no longer impossible. - Files do not shrink, as they used to (but not predictably) in some cases with MFC. You can use the MKOPTIM example to copy a file to a new one without gaps, to shrink it back.
If any of these issues matter to you, you will need to derive your own custom c4_Strategy class which implements to old behavior, using code present in src\mfc.cpp (see 1.8.4 - this file is no longer in 1.8.5).
Note that all the above changes *can* be implemented, even with stdio as I/O system, but they will need platform-dependent modifications.
From README.TXT:
The Metakit release is split up into a number of different packages, each of which can be downloaded as a separate archive.
ESSENTIAL INFORMATION
Not every file mentioned here is included in each package:
These notes should be part of each archive - README
For installation/build notes, see the file - INSTALL
All the latest changes are summarized here - WHATSNEW
Most documentation is in HTML, starting at - README.htmlEach of archives below unpacks in a directory with the same name as the archive, there's no risk of overwriting when you unpack more than one.
FREELY DOWNLOADABLE RELEASES
The download URL for these files is: https://www.equi4.com/metakit/pub/
mk4-1.8.5.tar.gz 0.3 Mb
mk4-1.8.5.zip 0.3 Mb
The main evaluation package. Sample code, HTML docs,
headers, also the DLL (and import library) needed to
use Metakit with the Microsoft Visual C++ 6.0 compiler.
mk4*-1.8.5-tar.gz (sizes vary)
There are many platform-specific builds. They only
contain the main include files and one or more library
builds for a specific platform (often "libmk4.a").DEVELOPER RELEASES
These are available to registered users only. The registration fee of $25 entitles you to one year of updates, see the website for details.
mk-dev-1.8.5.tar.gz 0.6 Mb
mk-dev-1.8.5.zip 0.7 Mb
Contains all include files (also inlined functions),
sample programs, an extensive test suite with about
a hundred small independent tests (lots of examples),
the complete documentation, and a few binaries for
Windows (compiled samples, as well as Mk4tcl + Mk4py).
This is a convenient way to get it all in one archive.
mk-dev-mfc-1.8.5.zip 1.9 Mb
Compiled builds of Metakit, for use with MSVC and MFC.
Configurations: Win 16/32, release/debug, static/dll.
mk-dev-msvc-1.8.5.zip 2.7 Mb
Compiled builds, again MSVC 6.0, but STL and Universal.
Configurations: Win 16/32, release/debug, static/dll.SOURCE CODE RELEASES
These are available to licensed users of Metakit only. The license fee is $165 for one year of updates ($90 for renewals), see the website.
mk-src-1.8.5.tar.gz 0.7 Mb
mk-src-1.8.5.zip 0.9 Mb
Contains full docs, sources, and all make/project files.
Everything except binaries in a single archive.