On 30/10/2012 08:48 AM, scott wrote:
>> A lot of developers write magic numbers to the registry so that when
>> your trial period ends, uninstalling and reinstalling the application
>> will not reset your trial period.
>
> Is this method really used? There are programs to record all
> reads/writes to the registry, so you really can delete all the keys
> created. Or you just restore a backup of the registry to start the trial
> again. I suspect they are a bit more cunning than this.

We used an expensive commercial web application which only works 
properly if you use Internet Explorer and only if you disable all web 
caching between you and the server. Because, obviously, the developers 
were too stupid to know how to set pages to expire. Some developers are 
very stupid.

Most users don't know what the "registry" is. I'm sure the above method 
works just fine in the majority of cases. Also, lots of programs require 
you to get a temporary "activation code", which won't work the second 
time around...

>> Okay, but why compile them?
>
> Speed?

I concur.

>> That's mostly the uninstaller's fault. I suppose there's a utility that
>> allows you to record the registry changes made by an installer, so that
>> when the utility is uninstalled you can follow up and scrub the registry
>> completely.
>
> That's dangerous though, because another program might have been
> installed since that changes or uses one of the settings the original
> program created/changed. If you go down this route (as some large
> companies do for custom automatic installer/uninstallers) then you need
> to do a lot of checking and testing for each program.

I've seen Linux try to do this with text files. Like, when you install 
an application, it renames the old config file, and when you uninstall 
it, it renames the old one back. Find if you uninstall stuff in LIFO 
order. Not so fine otherwise...

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