No
... Don'T think the rules or spell cover this...
From the spell text itself.
"This spell may be used only defensively, not aggressively."There within the spell is a general guideline.
The writers could not hope to have covered individually in the text every corner case example so they used that sentence which is fairly general and all encompassing (and in line with how almost all spells/effects like it have worked in 3.0 onward). While an explanation of a specific example does follow it is separated by a period not a comma so the two parts could be taken separate not just the latter as the only example of the former.
It does already have someone leeway, example: casting a summoned creature entirely outside it to attack for you, however in the case of a creature actually exiting the barrier even in part that doesn't seem in line with the spell text.
Only one person can be within the antilife shell: the caster. If your GM has allowed the party to exist inside of it, it's up to him/her as to how this is taken care of.
It is a 10 foot emanation. Assuming other party members started within that distance before it was cast they could potentially fit (though if they left it they could not reenter unless some form of selective spell feat or ability was somehow in play or they had spell resistance and passed that).
I'll concede that it can be viewed as such but I'll keep my interpretation.
That's fine but that would be a house rule. Different forum. By the rules multiple medium creatures can fit in a 10foot radius emanation. In fact also IIRC this came up a few years back regarding a different question, basically creatures within that distance when the spell is cast could hit the caster if he didn't also move away from them, they would already be inside the protection when it went up so would be unhindered unless they moved out of it or the caster moved away moving them out of it (and forcing it's normal rules to come into play).
It is a 10 foot emanation. Assuming other party members started within that distance before it was cast they could potentially fit (though if they left it they could not reenter unless some form of selective spell feat or ability was somehow in play or they had spell resistance and passed that).that's exactly how we interpreted it....
Our cleric cast the spell while we were all inside the 10 feet emanation. it was cast such as the border of the emanation was just short of the creature. Then the sorcerer moved next to creature while still being inside the shell. He then wanted to make a touch attack.
Hence the question, as to make a touch attack, at least part of his arm needs to exit the shell....can he pull back his hand afterward? we ruled no...but wanted to see if this was the correct interpretation...
I don't think there is a hard rules answer for this but I think, of the examples that exist in the rules that are close enough to it (including in it's own rules text), in general trying to exploit defensive spells like this simply causes them to pop and stop.
You can't simply reach just a hand out to touch an opponent, combat in ADnD/PF is not that specific as to how a hit is registered. Each attack roll might be the combination of several attempts, feints, probes at the opponent, etc. It's creating all kinds of loop holes, with attack of opportunity, etc, by this offensive action that I think it's best to treat it like the other example given. As I stated above, they're separated by a period not a comma. That would imply the example given isn't the only example of when the bubble pops, it's just an example of when the bubble would pop.
I think the strongest case that could be made is it causes the bubble to pop as you've tried to exploit it, by directly attacking out of it you've broken it just as directly attacking out of invisibility would break it, and the magic says "This spell may be used only defensively, not aggressively", or I would rule the person who tried to reach out of it finds himself outside the bubble in an adjacent square or squished into the square with the creature he was trying to attack.
Basically I would go with the answer that creates the least rules clutter and allows the current rules to be supported without figuring out 2-3 house rules on the spot for the poor GM. I think "The bubble pops" is the easiest answer and supported by the rules text example given.
However, as a very important final note, this seems deep into GM's call territory. So whatever your GM decided should be right.