DS throws massive tantrum when I tell him "its time to tidy up - we have to stop playing"

[Dominique07]

I am totally avoiding taking DS, 27 months, to public places because although he plays very nicely and becomes very absorbed in play he finds 'tidy up time' very stressful - he can't bear to put away/have anyone take his toys away from him. He can play solidly for hours.
I try to give him warnings and distract him with what we will do next but he gets very upset and it is near impossible to ever leave in a dignified manner with poor DS kicking and screaming!
I feel sorry for him because he obviously loves playing with different toys we don't have at home... I suppose I just have to go more often so he gets used to the routine. But how do I avoid the tantrum? When we go to the park he can get into equally traumatic tantrums over other children's toys, happy to share his but not happy to return other children's toys at the end of play time.
In fact the only place we don't have this problem is when we stay at home, but at home he often behaves very badly; throwing toys and acting very destructively.
Any advice?

He's very little and it's a very hard lesson to learn! I don't always wnat to share things and I'm 35!
Firstly it's a phase and it will pass (you really will not be doing this whan he's 18).
Secondly he's so little I would try distraction as my main tool. Can you produce a snack and stick the toy out of the way as he gets it?
My dd has always liked to say a formal 'bye bye' to toys or whatever-she is 4 and didn't want to leave the frog we found in the park today, but after I'd said 'say goodbye to mr frog' she did and walked off with us.
I assume by 'public places' you mean playgroups and so on? They will all be used to seeing wailing children leaving - if that's when it kicks off than I wouldn't worry about it and I would keep going -he won't learn if you stop going.
Throwing toys is normal for this age, but be consistent in your response -be that a firm no or ignoring him.
He will learn to share like it or not and you just have to keep at it -I've never been a stickler for turn taking and sharing, but my 3 all do it automatically now and so will your ds eventually.

Thanks for your reply, yes I'm glad to hear its just a phase. And he also does a very formal "bye bye choo choo/truck" when he is in the mood. Aren't they funny?
Honestly, no matter what tempting treat I produce, he scuttles off with his arms full of his chosen toys i.e. ALL of the trucks/dinosaurs/trains... keeping his eyes on me, at first its a game to see if I'll chase him but when he realises that everyone is going home, yes from playgroup, he gets really upset and literally throws himself on the floor.

Oh well, we'll just have to keep going, sigh!