[olpc-software] Package manager stuff

[Mike Hearn]

I've reverse engineered enough InstallShields in the past few years to
know that Windows has quite sophisticated DLL versioning - the fact that
older apps didn't use it says more about the poor standards of developer
education (and the lack of MSI) back then. 

Every DLL has version metadata embedded in the headers, which installers
can and do use to verify dependencies. DLLs that do the same thing but
that are incompatible are given different names, see MSVCR70.DLL,
MSVCR71.DLL, MSVCRT40.DLL and so on.

Programs like Softricity/Thinstall solve a bunch of problems, poorly
written software being one of them but other things include the fact
that Windows installers often aren't scriptable so deploying them across
a network can be a real pain. Fortunately that same mistake has not been
repeated on Linux.

> DLL hell is the windows nightmare that means that
> most people reinstall windows from scratch every 6 months to a year.

That's usually due to the system getting bogged down under the weight of
malicious software, or software that thinks it's special enough to load
a ton of stuff at startup time in my experience. 

I think we're getting distracted by Windows here - MacOS X does no
dependency checking at all yet you can have multiple versions of
Firefox, Camino, SeaMonkey, Thunderbird etc installed at once. It's
definitely possible to do this.

thanks -mike