Base revisions

Author: jgg
Date: 1998-07-02 02:58:12 GMT
Base revisions

1 files changed, 84 insertions, 0 deletions

diff --git a/apt-pkg/contrib/error.h b/apt-pkg/contrib/error.h
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+// -*- mode: cpp; mode: fold -*-
+// Description								/*{{{*/
+// $Id: error.h,v 1.1 1998/07/02 02:58:13 jgg Exp $
+/* ######################################################################
+   
+   Global Erorr Class - Global error mechanism
+
+   This class has a single global instance. When a function needs to 
+   generate an error condition, such as a read error, it calls a member
+   in this class to add the error to a stack of errors. 
+   
+   By using a stack the problem with a scheme like errno is removed and
+   it allows a very detailed account of what went wrong to be transmitted
+   to the UI for display. (Errno has problems because each function sets
+   errno to 0 if it didn't have an error thus eraseing erno in the process
+   of cleanup)
+   
+   Several predefined error generators are provided to handle common 
+   things like errno. The general idea is that all methods return a bool.
+   If the bool is true then things are OK, if it is false then things 
+   should start being undone and the stack should unwind under program
+   control.
+   
+   A Warning should not force the return of false. Things did not fail, but
+   they might have had unexpected problems. Errors are stored in a FIFO
+   so Pop will return the first item..
+   
+   I have some thoughts about extending this into a more general UI<-> 
+   Engine interface, ie allowing the Engine to say 'The disk is full' in 
+   a dialog that says 'Panic' and 'Retry'.. The error generator functions
+   like errno, Warning and Error return false always so this is normal:
+     if (open(..))
+        return _error->Errno(..);
+   
+   This source is placed in the Public Domain, do with it what you will
+   It was originally written by Jason Gunthorpe.
+   
+   ##################################################################### */
+									/*}}}*/
+// Header section: pkglib
+#ifndef PKGLIB_ERROR_H
+#define PKGLIB_ERROR_H
+
+#include <string>
+#include <vector.h>
+
+class GlobalError
+{
+   struct Item
+   {
+      string Text;
+      bool Error;
+   };
+   
+   vector<Item> List;
+   bool PendingFlag;
+   
+   public:
+
+   // Call to generate an error from a library call.
+   bool Errno(const char *Function,const char *Description,...);
+
+   /* A warning should be considered less severe than an error, and may be
+      ignored by the client. */
+   bool Error(const char *Description,...);
+   bool Warning(const char *Description,...);
+
+   // Simple accessors
+   inline bool PendingError() {return PendingFlag;};
+   inline bool empty() {return List.empty();};
+   bool PopMessage(string &Text);
+   void Discard() {List.erase(List.begin(),List.end()); PendingFlag = false;};
+
+   // Usefull routine to dump to cerr
+   void DumpErrors();
+   
+   GlobalError();
+};
+
+/* The 'extra-ansi' syntax is used to help with collisions. This is the 
+   single global instance of this class. */
+extern GlobalError *_error;
+
+#endif