Honestly, I would like to see habitual public drug users who get convicted of that sentenced into a red light district of some sort as punishment. The conviction allows the "system" to sentence them against their free will. They are going to do drugs regardless of the threat of jail, but at the same time, the rest of society shouldn't be subjected to their behavior. If nothing else, ignoring it is pretty unsanitary and can lead to disease, etc. Based on this article, it's fairly unsafe as well.
The "old" method of jail doesn't work and drug waring has stripped us of so many freedoms, people that came before it probably wouldn't recognize the country. On the other hand, just allowing it to happen isn't a solution either.
The only good thing jail does for an addict is forces them to be clean and clear headed for a little while, assuming they aren't smuggled in.