Reliable software [was Re: Xah's Edu Corner: Responsible Software Licensing]

[Steven D'Aprano]

robic0 wrote about software liabilities:

> If the software opens a file and is in the middle of writing to it,
> then the user dumps the power to the machine and ends up having to
> reformat, thereby losing all his data, at what point does the 
> liability stop? And how is fault proven or dished out? Does the
> law specifically state "repeatability" in its language?

This question is hardly unique to software. All 
manufacturers and suppliers have to deal with the 
question of what is covered by warranty.

But it is possible to code defensively. For instance, 
instead of writing directly to the user's file, you 
should write to a temporary file, then when the write 
is complete, you rename the temp file to the "real" 
file. On some OSes that can be an atomic operation, but 
even if it is not, your danger zone where a power 
failure can cause the user to lose data is strongly 
reduced.

As a general rule, closed source software suppliers 
have a terrible reputation for responding to bug 
reports quickly and in good faith. It sometimes seems 
that the bigger and more successful the software 
supplier is, the more likely they are to sit on bug 
reports, doing nothing to fix them, and threaten to sue 
if you disclose -- all the more so if it is a security 
exploit.


Follow-ups to comp.lang.python please.


-- 
Steven.