From: Li Chen <chen_li3@...>
Date: 2008-09-21T07:47:27+09:00
Subject: Re: update a field in CSV file using fastercsv

Gregory Brown wrote:
> On Sat, Sep 20, 2008 at 5:19 PM, Li Chen <chen_li3@yahoo.com> wrote:
>>> 1.  Open the existing data for reading
>> Thank you very much.
>>
>> One more question: Is this the same idea behind what we do with 'save'
>> or 'save as' in microsofte WORD or EXCEL?
> 
> An atomic save, as James suggested by the 4 steps above, is
> essentially the same as a "Save" in Word or Excel.
> 
> A Save is just two "Save As" calls.
> 
> I've got a file called "A"
> I make some changes to it, then
> I save it as "B"
> Once I am sure that my changes to "B" are okay, I save it as "A", to
> replace the original file.
> 
> The reason we need to do things this way is that (at least in Ruby,
> but in most languages I'd imagine), there isn't really a way to make a
> change to a file while you're reading it.
> 
> So we read in the file, writing another file with our changes.
> Then when we're done reading and writing, we replace the old file with
> our new one.  Conceptually, this ends up accomplishing the same thing,
> it lets us make changes to a single file.  The second file is just a
> temporary file for doing work on.
> 
> Make sense?
> 
> -greg


They really make sense.

Thank you very much,

Li
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