When you make a meal at home, you generally don't call the child to the table until the meal is ready. In a restaurant, there is always a period of waiting for food, making meal time longer than usual. To curb his hunger while he's waiting, bring snacks like Cheerios or crackers. And bring some small toys that he can play with on his tray or on the table.
The type of restaurant also has an effect. Choosing a family restaurant that is tolerant of children and has diversions for them may prevent disgusted looks from adults when your child makes a mess on the floor or cries to get down.
Make sure that someone understands that he or she will be the one to miss some of the adult conversation and take the child out to run around for a few minutes if necessary. I saw a good example of dealing with this recently in a restaurant. One parent ate dinner while the other attended to the toddlerand then their roles switched.
You never know what mood a toddlerwill be in, so be ready to leave if it is not working out. I recently went to dinner with a friend and her preschool child. When he would not settle down and was annoying everyone around us, I said, "We can leave, you know." She cancelled our order and we left. I am sure the restaurant was happy to be rid of an obstreperous child and didn't mind losing our business.