patternMinor
Code review of forward invocation
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codeforwardreviewinvocation
Problem
Here's the situation. I'm writing a simple game and I had two main actors:
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So far so good, then I decided to add HUD components on top of the grid (a score, a timer and other stuff). The most reasonable choice seemed to wrap such HUD components along with the grid into a new
And here comes the design issue: I need the controller to talk to the
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Expose a
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Forward the invocation made to
The first options looks like the most convenient, but I cannot get myself into liking it, due to the Law of Demeter.
So I decided to go for the second approach and do something like
It works as expected, but I'd like to have a sec
GameController and GridView.-
GridView is a UIView subclass displaying a grid with which the user interacts. It defines its custom delegate protocol (GridViewDelegate) for handling callbacks such as gridView:didSelectTile and others.-
GameController is the game controller (duh!) which instantiate a GridView and set itself as a delegate, therefore implementing the GridViewDelegate protocol.So far so good, then I decided to add HUD components on top of the grid (a score, a timer and other stuff). The most reasonable choice seemed to wrap such HUD components along with the grid into a new
UIView subclass called GameBoard.And here comes the design issue: I need the controller to talk to the
GridView and I think there's two reasonable options here.-
Expose a
gridView property and do something like[self.gameBoard.gridView doStuff];-
Forward the invocation made to
GameBoard directly to GridView overriding the forwardInvocation: method of GameBoardThe first options looks like the most convenient, but I cannot get myself into liking it, due to the Law of Demeter.
So I decided to go for the second approach and do something like
// The GameBoard serves a proxy between the GameContoller and the GridView
- (void)forwardInvocation:(NSInvocation *)anInvocation {
if ([self.gridView respondsToSelector:anInvocation.selector]) {
[anInvocation invokeWithTarget:self.gridView];
} else {
[super forwardInvocation:anInvocation];
}
}
// This method is necessary for the above forwardInvocation to work
- (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector {
NSMethodSignature * signature = [super methodSignatureForSelector:aSelector];
if (!signature) {
signature = [self.gridView methodSignatureForSelector:aSelector];
}
return signature;
}It works as expected, but I'd like to have a sec
Solution
I think you trying to overengineer solution a bit. First of all View should not do any stuff at all. View is just a View, sheet of paper. Maximum of view's responsibility is layouting himself. So controller should take care of other view-related stuff.
In this case I probably prefer to think about gridView as legitimate subview of GameBoard. I really doubt Demetra suffering when you doing something like
So my advice is to use
In this case I probably prefer to think about gridView as legitimate subview of GameBoard. I really doubt Demetra suffering when you doing something like
[self.view.titleLabel sizeToFit]. So my advice is to use
[self.gameBoard.gridView doStuff]; as simplest and straightforward solution.Context
StackExchange Code Review Q#20749, answer score: 4
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