I have a fairly liberal opinion on this mixed with a policy to make Shang Yang Proud.
Usually I think the public is best served by offenders being offered outpatient rehab as long as they can show family support for their housing and personal upkeep during that time. If they have the means to pay for this rehab themselves, then that's part of any restitution that should be made but if they're broke but have someone in their family letting them sleep on a couch then the state can subsidize the cost. If there isn't any family support, then an in-patient intensive rehab for first time offenders with felony convictions for all repeat offenders for periods of at least five years.
However, that's for someone caught with one drug in their possession. Anyone with two or more substances that can get you hooked for a public intoxication charge would be immediate execution. If you're the type to double your pleasure, double your fun, by mixing opiates and other sedatives, or alcohol and cocaine, or any of the other myriad combinations then we're all better off without you.
Naturally, this will lead to the knock-on benefit of executing millions of niggers, who never just do drugs but indulge in five course drug buffets before retiring to the alleyway for brandy and cigars dipped in formadelhyde while the ladies adjourn for purple drank in the OTB parking lot.