Kevin Smith wrote:
What I'm questioning now is the idea that, in generators, the implicit
first yield should occur *before the defaults are evaluated*. I don't
think that's a tenable position. Is there an implementation problem
with inserting the implicit first yield *after* the defaults are
evaluated but *before* the rest of the function body?
Not particularly, and this was where I landed at first.
In the SpiderMonkey implementation, at first, the bytecode emitter emits
the implicit yield opcode (JSOP_GENERATOR) before all other generated
code. But since then some conditional opcodes are emitted even before
the implicit yield:
http://dxr.mozilla.org/mozilla-central/js/src/frontend/BytecodeEmitter.cpp.html#l2620
Other implementations may generate different intermediate or target
forms from source, but I think the choice of where to put the implicit
yield can be made either way without hardship.
Other implementors should weigh in.
/be
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