Add (optional) fully lexically scoped blocks to the MOO language #366
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abesto
reviewed
Aug 13, 2024
As new options are added, the granularity needs to better and more descriptive.
Rework variable name binding to have a notion of pre-compilation declarations (UnboundNames) and post-compilation bound names (Names).
Adds a new notion of block scoped variables, declared using new syntax "let x =". Adds new block scope with "begin" and "end" keywords. Existing block structures like while/if-elseif-else/try/for are also lexically scopable. Also adds explicit global variable assignment / declaration via "global" By default variables are global, to keep backwards compatibility with LambdaMOO.
* Adds new keyword 'const' which should in theory allow a variable to be assigned to only once in the given lexical scope. * Add a test for disabled lexical scoping * Also clarifies the CompileError more specifically
Introduces a new-type "BuiltinId" to get away from using usize offsets explicitly throughout the code.
PC jumps between scopes was not properly popping out the scopes in the stack inbetween.
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#281
begin/endblocks.letdeclares a lexically scoped variable in the current block context (begin,try,while,if,for)globalrefers explicitly to a verb-global variable, which are the existing LambdaMOO defaultsconstcreates a variable binding which can only be assigned to once, at its declaration--lexical-scopes=falseto thedaemon