doc/libapt-pkg2_to_3.txt

   1 libapt-pkg v2 to v3 incorperates several source-incompatible changes that
   2 people need to be aware of.. Many of this changes are done so that most old
   3 source will continue to function, but perhaps at reduced functionality.
   4
   5 * pkgDepCache is no longer self initilizing, you have to call the Init
   6   method separately after constructing it. Users of pkgCacheFile do not
   7   need to worry about this
   8 * GetCandidateVer/etc is gone from the pkgCache. It exists only in the
   9   DepCache and is just an inline around the new Policy class
  10 * TargetVer/TargetDist have been eliminated. Nothing should have been using
  11   these.
  12 * There is a policy class. The v0 policy engine which has been used since
  13   APT 0.0.0 is instantiated by the DepCache by default. However pkgCacheFile
  14   constructs and initializes the new v4 engine. People accessing GetCandidate
  15   version outside of a CacheFile/DepCache will need to instantiate and
  16   initialize a policy engine on their own.
  17 * All byte counters are now doubles to advoid 4G wraparound. The compiler
  18   should generate warnings on any incorrect use of these.
  19 * The PriorityType/CompType/DepType functions have been moved out of the
  20   iterators and into generate static functions of pkgCache - inline stubs
  21   are left in the iterators.
  22 * The deb dependency element parser has been made into a static function
  23   of the list parser and enhanced to optionally understand architecture
  24   restrictions.
  25 * TagSections no longer include the trailing \n. This means that the
  26   Offset/Length of a package record in the version structure also does not
  27   include the trailing \n.
  28 * GenCaches::SelectFile accepts a site parameter now too.
  29 * Global version compare functions are gone. If you
  30     #define APT_COMPATIBILITY 1
  31   They will come back as they were before. Code should be updated to
  32   reference the compare functions to the VersioningSystem (VS) referenced
  33   by the Cache or _system structures.
  34 * Initialization is now two stage (define APT_COMPATIBILITY..) The first
  35   stage, pkgInitConfig is called before commandline parsing, and
  36   pkgInitSystem is called after. This gives the user the oppertunity to
  37   override default settings from the config files before startup has been
  38   finalized.
  39 * pkgSourceList has been gutted. All the junk that was in there before is
  40   cleaned up and put in the pkgIndexFile class. There is very little API
  41   corrispondence here..
  42 * pkgMakeStatusCacheMem is gone, pkgMakeStatusCache does the same thing if
  43   you set the AllowMem flag. Also, you can get a copy of the map used to
  44   store the cache to advoid having to remap it in the calling code. A bunch
  45   of other cache related functions are gone, but nobody should have been using
  46   them in the first place!
  47 * Downloading the 'Package' and 'Source' index files is different, use
  48   the GetIndexes call in SourceList.
  49 * SourceRecords::Parser::Source is gone, replaced with Index which does
  50   much the same thing.
  51 * DynamicMap has changed slightly, nobody should care
  52 * pkgMakeOnlyStatusCache exists, which creates a really small cache that
  53   only contains the status file, and in memory.
  54 * The pkgRecords stuff is changed to abstract through the index file list
  55   (should be transparent largely)
  56 * Locking is handled differently, there is no dpkg lock class, the _system
  57   class provides Lock/UnLock methods
  58 * pkgDepCache is not a subclass of pkgCache, it aggregates it now. Some
  59   compatibility functions are provided that make this transition fairly
  60   easy.
  61 * The following functions have had minor argument changes:
  62    -   pkgSimulate(pkgDepCache &Cache);
  63    +   pkgSimulate(pkgDepCache *Cache);
  64
  65    -   pkgProblemResolver(pkgDepCache &Cache);
  66    +   pkgProblemResolver(pkgDepCache *Cache);
  67
  68    -   pkgDepCache(MMap &Map,Policy *Plcy = 0);
  69    +   pkgDepCache(pkgCache *Cache,Policy *Plcy = 0);
  70
  71    -   pkgOrderList(pkgDepCache &Cache);
  72    +   pkgOrderList(pkgDepCache *Cache);
  73
  74    -   pkgPackageManager(pkgDepCache &Cache);
  75    +   pkgPackageManager(pkgDepCache *Cache);
  76
  77    -   pkgCache(MMap &Map,bool DoMap = true);
  78    +   pkgCache(MMap *Map,bool DoMap = true);
  79
  80    -   pkgCacheGenerator(DynamicMMap &Map,OpProgress &Progress);
  81    +   pkgCacheGenerator(DynamicMMap *Map,OpProgress *Progress);
  82
  83    -   pkgTagFile(FileFd &F,unsigned long Size = 32*1024);
  84    +   pkgTagFile(FileFd *F,unsigned long Size = 32*1024);
  85
  86 * Configuration class is const-correct
  87 * The legacy ability to create a PkgFileIterator that started at Begin
  88   is gone, everyone should be using FileBegin().
  89 * A new dependency relation called obsoletes that is similar to conflicts.