In my training, we often include drills against an opponent who is about to draw his longer weapon while drawing my own weapon. I found it to be quite easy (most of the time..) to rush the attacker and cut his arm while he was in the middle of drawing. You can also try to use your live (empty hand) to block the drawing hand and cut/stab directly (to the face, neck, shoulder, wherever). Of course you would need to follow up with something that keeps your attacker from continuing with his other hand or fighting you in some other ways. A ´cut drawing hand - cut other hand - stab thigh/cut leg tendon - backoff´ combination would be an example.
The rushing strategy works especially well against people who don´t have developed the right feeling for fighting ranges (too near while drawing) and quick-drawing.
In in a rioting mob though, most people will already have their weapons in hand, I suppose. Generally, it could be useful to get as close as possible, because a machete/long weapon is difficult to handle in very close range, while you can use your short weapon more easily. As maxegb said, try practicing an evasion move quickly followed by an attack. An untrained machete wielder will often exaggerate his movements, swing wildly at you, and when missing, will have problems with controlling/stopping the swing to follow up. This could be your chance to close the gap and attack.
Using other weapons or distractions (pepper spray, sand, carrying bags, backpacks as shields, marbles to annoy attackers running after you etc.) is a good idea. Train with them, and make sure you have them on you when you need them.
To be succesfull with the "rushing a drawing opponent" strategy, you need to be very fast with your own draw. You can also practice carrying your folder covertly in your hand, or even opened but covert.
I hope I have helped you a bit, practice and take care,
Judge
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"Peace is not without conflict; it is the ability to cope with conflict" - Leo Giron
[This message has been edited by judge (edited 05-29-2000).]