Current scoping mechanism is broken

[GoogleCodeExporter]

I've talked with Manuel and we both agree that the scoping mechanism that is 
currently 
implemented is broken.  There are a number of bugs already submitted that have 
to do with the way 
that we currently create and search through scopes.  We've decided to try to 
replace it with what 
essentially will be a stack of maps from variable names to the objects they are 
bound to.

Original issue reported on code.google.com by [email protected] on 2 Jun 2010 at 2:36

• Blocking: Variable lookup for write accesses is broken #32, Lambda does not capture state fields correctly #31, Writing to global variables leads to generation of erroneous code #27, Passing var to method which takes multiple arguments generates erroneous code #26

[GoogleCodeExporter]

To elaborate more on the semantics of this change, each scoping level will be 
represented by a single map in the 
stack of maps.  Whenever we enter a new scope, we push a new map onto the 
stack.  Whenever we need to 
perform a lookup for a variable name, we search from the top of the stack 
downwards, using the first entry that 
we find.  If we do not find anything, then we throw an error.

This also alleviates some of our issues with lambdas.  Whenever we instantiate 
a lambda, we make a copy of the 
current map and store it with the lambda.  That way, the state of the bound 
variables in the lambda is essentially 
frozen.

Original comment by [email protected] on 2 Jun 2010 at 2:43

[GoogleCodeExporter]

Original comment by [email protected] on 2 Jun 2010 at 3:44

• Changed state: Started