Read and Write the same file

[Grant Edwards]

On 2007-05-01, Gabriel Genellina <gagsl-py2 at yahoo.com.ar> wrote:
> En Tue, 01 May 2007 20:03:28 -0300, JonathanB <doulos05 at gmail.com>  
> escribió:
>
>> Ok, so this is the scenario. I need to create a simple, no-frills XML
>> editor for non-technical users. It doesn't have to do anything fancy,
>> what I want is a series of text boxes with the text contents of the
>> elements pre-printed. Then the users can type their changes into the
>> text boxes and click submit and it will load the changes in. So here
>> is the problem, this means I need to open the same file as both read
>> and write. How do I do this? I'm slowly learning the DOM stuff that I
>> need to know to do this, but this file thing I haven't been able to
>> find anywhere.
>
> Open the file for reading; read and parse the document; close the file.
> Build form and show to the user.
> Get data after user clicks OK.
> Build document, open file for writing, write document, close file.
>
> Reading and writing happen on two separate stages, and you dont have to  
> keep the file open all the time.

A safer way to do this is to write the new version to a
temporary file, close the temporary file, then rename it.
There's much less chance of losing data that way -- no matter
when the program or computer crashes, you've got a complete
copy one version or the other.

-- 
Grant Edwards                   grante             Yow!  I am having FUN... I
                                  at               wonder if it's NET FUN or
                               visi.com            GROSS FUN?