Regardless of where a pistol is carried, a holster is the ONLY way to carry it not only safe, but ready as well.
I refuse to carry a pistol that even has a safety anymore. In a real-life situation, all I want to do is to point and click and not be distracted with racking or even wondering if there's one in the chamber or not (did I or didn't I?... give me a sec, BG, while I check this out.)
So my carry weapons are the likes of a 642, Rohrbaugh R9s 9mm (no safety on board), LCP (no safety on board) and an XD9SC (no safety on board) and all carried with one in the chamber.
While I also carry a Commander in DefCon1, the 1911 is a different platform altogether and the safety on it is not used in the same way that safeties are on other pistols (and not part of this discussion).
However, a proper holster will always totally enclose the trigger on a pistol, so an accidental hang-up and trigger pull is simply not possible.
Even a pistol like the LCP shouldn't be carried naked in a pocket. There are pocket holsters designed especially for pocket carry, and they not only keep the pistol safe, but make it more readily available by keeping the pistol properly oriented in the pocket for faster access.
A pistol without a pocket holster will invariably end up upside down or sideways in the pocket which not only makes it more dangerous to carry (safety or not), but also makes it harder to get to quickly if needed.
My most often carry is the Rohrbaugh in an Uncle Mikes #1 holster (an IWB holster), but that I carry in the front pocket of my jeans with the clip over the edge of the pocket.
Any shirt I have (that I wear hanging out) will totally hide it, it's kept safe in it's holster, and with the grip just peaking over the edge of the pocket, I can draw as quickly as any IWB holster.