Tuesday, April 17, 2012

Dart Language progress update

Posted by Gilad Bracha


The Dart language team gathered to discuss some of the open issues with the language.


Language Bugs: Will review language bugs and either fix, mark as deferred to future release (meaning no decision but distinctly possible in the future) or close. 30 bugs already processed last week.

Cascades: The new dart2js compiler has implemented the spec. We will review to see if spec needs minor adjustments in light of implementation experience. We don’t expect any significant changes.

Defaults in interfaces:  We expect to support these. Intended semantics are to give a warning if violated by implementor. However, if no default is given in the interface we will not interpret that as a default of null.  People can override in the default code if they want to, and may have reason to.  In any case we have no way force them to do otherwise. We will pin down draft specification.

Generics reification: We discussed whether to back off of that. The decision is to retain reification unless major problems arise in dart2js. We do not anticipate such problems, but once dart2js implements the semantics we can quantify any costs.

Multiple initialization points for finals:  Tendency is to keep current spec and fix implementation, but we do need to see what impact it has on code base. Ongoing discussion.

Repeated keys in map literals: We noted that we could disallow this if the keys are strings constants, but since we are hoping to generalize that, it might not make any sense.

Switch statement: Decision is to restrict switch to operate on compile time constants of uniform type - either int or String. We could extend this to enums if we ever add them. The motivation is that switch is only useful as a highly optimized jump table, and so we should focus on that; otherwise use if-else, it’s clearer. We will adjust spec accordingly.