better non-virtual metaIndex.LocalFileName() implementation

We can't add a new virtual method without breaking the ABI, but we can
freely add new methods, so for older ABIs we just implement this method
with a dynamic_cast, so that clients can be more ignorant about the API
here and especially don't need to pull a very dirty trick by assuming
internal knowledge (like apt-get did here).

apt-pkg/deb/debmetaindex.cc

@@ -78,7 +78,6 @@ string debReleaseIndex::MetaIndexURI(const char *Type) const
    return Res;
 }
 
-#if APT_PKG_ABI >= 0x0413
 std::string debReleaseIndex::LocalFileName() const
 {
    // see if we have a InRelease file
@@ -92,7 +91,6 @@ std::string debReleaseIndex::LocalFileName() const
 
    return "";
 }
-#endif
 
 string debReleaseIndex::IndexURISuffix(const char *Type, string const &Section, string const &Arch) const
 {

apt-pkg/deb/debmetaindex.h

@@ -54,8 +54,9 @@ class debReleaseIndex : public metaIndex {
    std::string MetaIndexURI(const char *Type) const;
 
 #if APT_PKG_ABI >= 413
-   virtual std::string LocalFileName() const;
+   virtual
 #endif
+   std::string LocalFileName() const;
 
    std::string IndexURI(const char *Type, std::string const &Section, std::string const &Arch="native") const;
    std::string IndexURISuffix(const char *Type, std::string const &Section, std::string const &Arch="native") const;

apt-pkg/metaindex.cc

@@ -0,0 +1,40 @@
+// Include Files                                                       /*{{{*/
+#include <apt-pkg/indexfile.h>
+#include <apt-pkg/metaindex.h>
+
+#include <stddef.h>
+
+#include <string>
+#include <vector>
+                                                                       /*}}}*/
+
+#if (APT_PKG_MAJOR >= 4 && APT_PKG_MINOR >= 13)
+std::string metaIndex::LocalFileName() const { return ""; }
+#else
+#include <apt-pkg/debmetaindex.h>
+std::string metaIndex::LocalFileName() const
+{
+   debReleaseIndex const * deb = dynamic_cast<debReleaseIndex const*>(this);
+   if (deb != NULL)
+      return deb->LocalFileName();
+
+   return "";
+}
+#endif
+
+metaIndex::metaIndex(std::string const &URI, std::string const &Dist,
+      char const * const Type)
+: Indexes(NULL), Type(Type), URI(URI), Dist(Dist), Trusted(false)
+{
+   /* nothing */
+}
+
+metaIndex::~metaIndex()
+{
+   if (Indexes == 0)
+      return;
+   for (std::vector<pkgIndexFile *>::iterator I = (*Indexes).begin();
+        I != (*Indexes).end(); ++I)
+      delete *I;
+   delete Indexes;
+}

apt-pkg/metaindex.h

@@ -41,8 +41,8 @@ class metaIndex
 
    // interface to to query it
 #if APT_PKG_ABI >= 413
-   // returns the path of the local file (or "" if its not available)
-   virtual std::string LocalFileName() const {return "";};
+   /** \return the path of the local file (or "" if its not available) */
+   virtual std::string LocalFileName() const;
 #else
    std::string LocalFileName() const;
 #endif
@@ -50,25 +50,12 @@ class metaIndex
    // Interface for acquire
    virtual std::string ArchiveURI(std::string const& File) const = 0;
    virtual bool GetIndexes(pkgAcquire *Owner, bool const &GetAll=false) const = 0;
-   virtual std::vector<pkgIndexFile *> *GetIndexFiles() = 0; 
+   virtual std::vector<pkgIndexFile *> *GetIndexFiles() = 0;
    virtual bool IsTrusted() const = 0;
 
-   metaIndex(std::string const &URI, std::string const &Dist, 
-             char const * const Type) 
-      : Indexes(NULL), Type(Type), URI(URI), Dist(Dist), Trusted(false)
-   {
-      /* nothing */
-   }
-
-   virtual ~metaIndex() 
-   {
-      if (Indexes == 0)
-	 return;
-      for (std::vector<pkgIndexFile *>::iterator I = (*Indexes).begin();
-           I != (*Indexes).end(); ++I)
-	 delete *I;
-      delete Indexes;
-   }
+   metaIndex(std::string const &URI, std::string const &Dist,
+             char const * const Type);
+   virtual ~metaIndex();
 };
 
 #endif

cmdline/apt-get.cc

@@ -136,28 +136,6 @@ static bool TryToInstallBuildDep(pkgCache::PkgIterator Pkg,pkgCacheFile &Cache,
    return true;
 }
 									/*}}}*/
-
-
-// helper that can go wit hthe next ABI break
-#if (APT_PKG_MAJOR >= 4 && APT_PKG_MINOR < 13)
-static std::string MetaIndexFileNameOnDisk(metaIndex *metaindex)
-{
-   // FIXME: this cast is the horror, the horror
-   debReleaseIndex *r = (debReleaseIndex*)metaindex;
-
-   // see if we have a InRelease file
-   std::string PathInRelease =  r->MetaIndexFile("InRelease");
-   if (FileExists(PathInRelease))
-      return PathInRelease;
-
-   // and if not return the normal one
-   if (FileExists(PathInRelease))
-      return r->MetaIndexFile("Release");
-
-   return "";
-}
-#endif
-
 // GetReleaseForSourceRecord - Return Suite for the given srcrecord	/*{{{*/
 // ---------------------------------------------------------------------
 /* */
@@ -176,12 +154,8 @@ static std::string GetReleaseForSourceRecord(pkgSourceList *SrcList,
       {
          if (&CurrentIndexFile == (*IF))
          {
-#if (APT_PKG_MAJOR >= 4 && APT_PKG_MINOR < 13)
-            std::string path = MetaIndexFileNameOnDisk(*S);
-#else
-            std::string path = (*S)->LocalFileName();
-#endif
-            if (path != "") 
+            std::string const path = (*S)->LocalFileName();
+            if (path != "")
             {
                indexRecords records;
                records.Load(path);