How about a bounty for a new windows installer using inno setup ?

[Thomas Mader via Digitalmars-d]

On Wednesday, 7 December 2016 at 23:00:13 UTC, Jim Hewes wrote:
> On 12/6/2016 10:31 PM, Thomas Mader wrote:
>>
>> The update case could be better supported by Inno by default 
>> though I
>> don't know how to really do it transactionally/atomic. Once 
>> everything
>> is on the drive, how would you be able to switch from the old 
>> directory
>> to the new one with one atomic action under Windows?
>>
>
> I'm not sure what you mean by switch the directory. If you mean 
> that the update uses a different directory for the program than 
> the original, then you can probably just use a "major" upgrade. 
> Windows Installer has the idea of minor upgrade and major 
> upgrade. (So, it's independent of whatever tools your using.) A 
> minor upgrade just updates the files that have changed. A major 
> upgrade essentially removes the original product totally and 
> installs the new one. Some people even use a major upgrade for 
> _every_ new version just to avoid problems that might occur 
> with a minor upgrade.

The Update is triggered by the application itself. If the install 
fails or is Canceled in the middle the application can not start 
anymore and so the user needs to do something manually.
It would be possible to update everything into a new directory 
and after everything is done just exchange the stuff in the 
already installed directory with the new update directory.
But even this operation isn't atomic even though it's much better.
What might work is to make it work like the Nix package manager.
NixOS (Nix Package manager) provides atomic updates because the 
entire system environment is build by links. Replacing a version 
with another one is just a matter of changing the link to the 
proper directory.

So in Windows you could do it the same. Install versions in 
separate directories. The installation directory is linking to 
the appropriate version directory. On update just install to new 
version directory and after everything is done just update the 
installation directory link to the new update directory.
No matter what happens either the old or the new application 
version should be workable.