[Python-3000] Switch/Case statement PEP

[Thomas Dixon]

I was reading the PEP regarding the Switch/Case statement (http:// 
www.python.org/dev/peps/pep-3103/), and have a few thoughts about it.

1) Proposed layout
	Here is how I propose the 'switch' statement to be constructed.  
Further on I will give the reasoning behind the syntax. As you can  
see,  I am also a fan of Alternative 1.

	case EXPR:
		on EXPR:
			SUITE
		on EXPR:
			SUITE
			continue
		else:
			SUITE
		
2) Statement Keywords
	You will notice 'switch' was replaced with what is typically found  
in the body of the switch statement, 'case'. Not only is it shorter,  
but I feel it also better describes what the statement actually does.  
You'll also notice that the 'case' keyword in the body was replaced  
with 'on'. To me, it just sounds natural. Using 'if' as some others  
have proposed may end up being confusing, and 'case' wasn't used in  
the body for obvious reasons.

3) Control flow
	The lone 'continue' in the example is indicative of another one of  
my proposals. In switch statements the 'break' used in most languages  
is almost completely redundant, and thus should be implemented by  
default. I also propose that the switch statement allows use of  
Python's loop control flow keywords. Which means that by default the  
flow doesn't 'fall through' in the absence of the 'break', but that  
one can force it to do so by using 'continue', as you might expect it  
to behave. Below I have proposed Python examples and their C  
equivalents to hopefully better explain what I mean.

-- Example 1:

	Python:
		
		case EXPR:
			on EXPR:
				SUITE

	C:

		switch (EXPR) {
			case EXPR:
				SUITE
				break;
		}

-- Example 2:

	Python:
		
		case EXPR:
			on EXPR:
				SUITE
				continue

	C:

		switch (EXPR) {
			case EXPR:
				SUITE
		}

I hope I explained myself well enough, and that I haven't taken up  
too much of your time.

Have a nice day,

Thomas Dixon
reikonmusha at gmail.com



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