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1% automatically generated by HelpGen from tempfile.tex at 10/Jan/99 19:24:44
2\section{\class{wxTempFile}}\label{wxtempfile}
3
4wxTempFile provides a relatively safe way to replace the contents of the
5existing file. The name is explained by the fact that it may be also used as
6just a temporary file if you don't replace the old file contents.
7
8Usually, when a program replaces the contents of some file it first opens it for
9writing, thus losing all of the old data and then starts recreating it. This
10approach is not very safe because during the regeneration of the file bad things
11may happen: the program may find that there is an internal error preventing it
12from completing file generation, the user may interrupt it (especially if file
13generation takes long time) and, finally, any other external interrupts (power
14supply failure or a disk error) will leave you without either the original file
15or the new one.
16
17wxTempFile addresses this problem by creating a temporary file which is meant to
18replace the original file - but only after it is fully written. So, if the user
19interrupts the program during the file generation, the old file won't be lost.
20Also, if the program discovers itself that it doesn't want to replace the old
21file there is no problem - in fact, wxTempFile will {\bf not} replace the old
22file by default, you should explicitly call \helpref{Commit}{wxtempfilecommit}
23to do it. Calling \helpref{Discard}{wxtempfilediscard} explicitly discards any
24modifications: it closes and deletes the temporary file and leaves the original
25file unchanged. If you don't call neither of Commit() and Discard(), the
26destructor will call Discard() automatically.
27
28To summarize: if you want to replace another file, create an instance of
29wxTempFile passing the name of the file to be replaced to the constructor (you
30may also use default constructor and pass the file name to
31\helpref{Open}{wxtempfileopen}). Then you can \helpref{write}{wxtempfilewrite}
32to wxTempFile using \helpref{wxFile}{wxfile}-like functions and later call
33Commit() to replace the old file (and close this one) or call Discard() to cancel
34the modifications.
35
36\wxheading{Derived from}
37
38No base class
39
40\wxheading{Include files}
41
42<wx/file.h>
43
44\wxheading{See also:}
45
46\helpref{wxFile}{wxfile}
47
48\latexignore{\rtfignore{\wxheading{Members}}}
49
50\membersection{wxTempFile::wxTempFile}\label{wxtempfilewxtempfilector}
51
52\func{}{wxTempFile}{\void}
53
54Default constructor - \helpref{Open}{wxtempfileopen} must be used to open the
55file.
56
57\membersection{wxTempFile::wxTempFile}\label{wxtempfilewxtempfile}
58
59\func{}{wxTempFile}{\param{const wxString\& }{strName}}
60
61Associates wxTempFile with the file to be replaced and opens it. You should use
62\helpref{IsOpened}{wxtempfileisopened} to verify if the constructor succeeded.
63
64\membersection{wxTempFile::Open}\label{wxtempfileopen}
65
66\func{bool}{Open}{\param{const wxString\& }{strName}}
67
68Open the temporary file, returns {\tt true} on success, {\tt false} if an error
69occurred.
70
71{\it strName} is the name of file to be replaced. The temporary file is always
72created in the directory where {\it strName} is. In particular, if
73{\it strName} doesn't include the path, it is created in the current directory
74and the program should have write access to it for the function to succeed.
75
76\membersection{wxTempFile::IsOpened}\label{wxtempfileisopened}
77
78\constfunc{bool}{IsOpened}{\void}
79
80Returns {\tt true} if the file was successfully opened.
81
82\membersection{wxTempFile::Write}\label{wxtempfilewrite}
83
84\func{bool}{Write}{\param{const void }{*p}, \param{size\_t }{n}}
85
86Write to the file, return {\tt true} on success, {\tt false} on failure.
87
88\membersection{wxTempFile::Write}\label{wxtempfilewrites}
89
90\func{bool}{Write}{\param{const wxString\& }{str}, \param{wxMBConv\&}{ conv = wxConvLibc}}
91
92Write to the file, return {\tt true} on success, {\tt false} on failure.
93
94The second argument is only meaningful in Unicode build of wxWidgets when
95{\it conv} is used to convert {\it str} to multibyte representation.
96
97\membersection{wxTempFile::Commit}\label{wxtempfilecommit}
98
99\func{bool}{Commit}{\void}
100
101Validate changes: deletes the old file of name m\_strName and renames the new
102file to the old name. Returns {\tt true} if both actions succeeded. If {\tt false} is
103returned it may unfortunately mean two quite different things: either that
104either the old file couldn't be deleted or that the new file couldn't be renamed
105to the old name.
106
107\membersection{wxTempFile::Discard}\label{wxtempfilediscard}
108
109\func{void}{Discard}{\void}
110
111Discard changes: the old file contents is not changed, temporary file is
112deleted.
113
114\membersection{wxTempFile::\destruct{wxTempFile}}\label{wxtempfiledtor}
115
116\func{}{\destruct{wxTempFile}}{\void}
117
118Destructor calls \helpref{Discard()}{wxtempfilediscard} if temporary file
119is still opened.
120