include/wverror.h

   1 /* -*- Mode: C++ -*-
   2  * Worldvisions Weaver Software:
   3  *   Copyright (C) 1997-2002 Net Integration Technologies, Inc.
   4  *
   5  * A class for managing error numbers and strings.
   6  */
   7 #ifndef __WVERROR_H
   8 #define __WVERROR_H
   9
  10 #include "wvstring.h"
  11
  12 /**
  13  * A class for managing error numbers and strings.
  14  *
  15  * It can have either a system error value, like those defined
  16  * in errno.h, or an arbitrary error string.  In either case, it
  17  * can return a string representation of the error message.
  18  *
  19  * This object is most useful for using as a base class of your own class,
  20  * for historical/backwards compatibility reasons.  Consider using a WvError
  21  * instead, and making it a member of your class instead of a parent.
  22  */
  23 class WvErrorBase
  24 {
  25 protected:
  26     int errnum;
  27     WvString errstring;
  28
  29 public:
  30     WvErrorBase()
  31         { noerr(); }
  32     virtual ~WvErrorBase();
  33
  34     /**
  35      * By default, returns true if geterr() == 0.
  36      * Might be overridden so that isok() == false even though no
  37      * error code has been specified.
  38      */
  39     virtual bool isok() const
  40         { return errnum == 0; }
  41
  42     /**
  43      * If isok() is false, return the system error number corresponding to
  44      * the error, -1 for a special error string (which you can obtain with
  45      * errstr()) or 0 on end of file.  If isok() is true, returns an
  46      * undefined number.
  47      */
  48     virtual int geterr() const
  49         { return errnum; }
  50     virtual WvString errstr() const;
  51
  52     /**
  53      * A replacement for the operating system ::strerror() function that
  54      * can map more kinds of error strings (especially in win32).
  55      */
  56     static WvString strerror(int errnum);
  57
  58     /**
  59      * Set the errnum variable -- we have an error.  If called more than
  60      * once, seterr() doesn't change the error code away from the previous
  61      * one.  That way, we remember the _original_ cause of our problems.
  62      *
  63      * Subclasses may want to override seterr(int) to shut themselves down
  64      * (eg. WvStream::close()) when an error condition is set.
  65      *
  66      * Note that seterr(WvString) will call seterr(-1).
  67      */
  68     virtual void seterr(int _errnum);
  69     void seterr(WvStringParm specialerr);
  70     void seterr(WVSTRING_FORMAT_DECL)
  71         { seterr(WvString(WVSTRING_FORMAT_CALL)); }
  72     void seterr_both(int _errnum, WvStringParm specialerr);
  73     void seterr_both(int _errnum, WVSTRING_FORMAT_DECL)
  74         { seterr_both(_errnum, WvString(WVSTRING_FORMAT_CALL)); }
  75     void seterr(const WvErrorBase &err);
  76
  77     /** Reset our error state - there's no error condition anymore. */
  78     void noerr()
  79         { errnum = 0; errstring = WvString::null; }
  80 };
  81
  82
  83 /**
  84  * A variant of WvErrorBase suitable for embedding as a member of your own
  85  * object, preferably called 'err'.  It adds some extra convenience functions
  86  * to remove function name redundancy, so you can say "obj.err.get()" instead
  87  * of "obj.err.geterr()", for example.
  88  */
  89 class WvError : public WvErrorBase
  90 {
  91 public:
  92     int get() const
  93         { return geterr(); }
  94     WvString str() const
  95         { return errstr(); }
  96
  97     void set(int _errnum)
  98         { seterr(_errnum); }
  99     void set(WvStringParm specialerr)
 100         { seterr(specialerr); }
 101     void set(WVSTRING_FORMAT_DECL)
 102         { seterr(WvString(WVSTRING_FORMAT_CALL)); }
 103     void set_both(int _errnum, WvStringParm specialerr)
 104         { seterr_both(_errnum, specialerr); }
 105     void set(const WvErrorBase &err)
 106         { seterr(err); }
 107
 108     void reset()
 109         { noerr(); }
 110 };
 111
 112
 113 #endif // __WVERROR_H