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578bfd0a AL |
1 | // -*- mode: cpp; mode: fold -*- |
2 | // Description /*{{{*/ | |
233b185f | 3 | // $Id: error.h,v 1.8 2001/05/07 05:06:52 jgg Exp $ |
578bfd0a AL |
4 | /* ###################################################################### |
5 | ||
6 | Global Erorr Class - Global error mechanism | |
7 | ||
8 | This class has a single global instance. When a function needs to | |
9 | generate an error condition, such as a read error, it calls a member | |
10 | in this class to add the error to a stack of errors. | |
11 | ||
12 | By using a stack the problem with a scheme like errno is removed and | |
13 | it allows a very detailed account of what went wrong to be transmitted | |
14 | to the UI for display. (Errno has problems because each function sets | |
15 | errno to 0 if it didn't have an error thus eraseing erno in the process | |
16 | of cleanup) | |
17 | ||
18 | Several predefined error generators are provided to handle common | |
19 | things like errno. The general idea is that all methods return a bool. | |
20 | If the bool is true then things are OK, if it is false then things | |
21 | should start being undone and the stack should unwind under program | |
22 | control. | |
23 | ||
24 | A Warning should not force the return of false. Things did not fail, but | |
25 | they might have had unexpected problems. Errors are stored in a FIFO | |
26 | so Pop will return the first item.. | |
27 | ||
28 | I have some thoughts about extending this into a more general UI<-> | |
29 | Engine interface, ie allowing the Engine to say 'The disk is full' in | |
30 | a dialog that says 'Panic' and 'Retry'.. The error generator functions | |
31 | like errno, Warning and Error return false always so this is normal: | |
32 | if (open(..)) | |
33 | return _error->Errno(..); | |
34 | ||
35 | This source is placed in the Public Domain, do with it what you will | |
36 | It was originally written by Jason Gunthorpe. | |
37 | ||
38 | ##################################################################### */ | |
39 | /*}}}*/ | |
578bfd0a AL |
40 | #ifndef PKGLIB_ERROR_H |
41 | #define PKGLIB_ERROR_H | |
42 | ||
2893f7b5 | 43 | #include <apt-pkg/macros.h> |
13500573 | 44 | |
578bfd0a | 45 | #include <string> |
578bfd0a AL |
46 | |
47 | class GlobalError | |
48 | { | |
49 | struct Item | |
50 | { | |
2893f7b5 | 51 | std::string Text; |
578bfd0a | 52 | bool Error; |
6c139d6e | 53 | Item *Next; |
578bfd0a AL |
54 | }; |
55 | ||
6c139d6e | 56 | Item *List; |
578bfd0a | 57 | bool PendingFlag; |
6c139d6e | 58 | void Insert(Item *I); |
578bfd0a AL |
59 | |
60 | public: | |
61 | ||
62 | // Call to generate an error from a library call. | |
6dc60370 DK |
63 | bool Errno(const char *Function,const char *Description,...) __like_printf(3) __cold; |
64 | bool WarningE(const char *Function,const char *Description,...) __like_printf(3) __cold; | |
578bfd0a AL |
65 | |
66 | /* A warning should be considered less severe than an error, and may be | |
67 | ignored by the client. */ | |
6dc60370 DK |
68 | bool Error(const char *Description,...) __like_printf(2) __cold; |
69 | bool Warning(const char *Description,...) __like_printf(2) __cold; | |
578bfd0a AL |
70 | |
71 | // Simple accessors | |
72 | inline bool PendingError() {return PendingFlag;}; | |
6c139d6e | 73 | inline bool empty() {return List == 0;}; |
2893f7b5 | 74 | bool PopMessage(std::string &Text); |
6c139d6e | 75 | void Discard(); |
578bfd0a AL |
76 | |
77 | // Usefull routine to dump to cerr | |
78 | void DumpErrors(); | |
79 | ||
80 | GlobalError(); | |
81 | }; | |
82 | ||
6f27a7fc AL |
83 | // The 'extra-ansi' syntax is used to help with collisions. |
84 | GlobalError *_GetErrorObj(); | |
85 | #define _error _GetErrorObj() | |
578bfd0a AL |
86 | |
87 | #endif |