On 12/19/12 4:25 AM, Walter Bright wrote:
On 12/19/2012 1:10 AM, Rob T wrote:
Using the JS code as an example, you are stating that the JS source
code itself
could just as well be viewed as the "bytecode", and therefore given
what I
previously wrote concerning the "advantages", I could replace
"bytecode" with
"JS source code" and achieve the exact same result. Am I Correct?
Yes.
I thought the claim was about ASTs vs. bytecode, which slowly segued
into source code vs. byte code. Are e in agreement there is a cost of
translating JS source code to AST format? (The cost may be negligible to
some applications but it's there.)
There's also the serialization aspect. Serializing and deserializing an
AST takes extra effort because pointers must be fixed. Bytecode can be
designed to avoid most of that cost.
On these two accounts alone, one may as well choose bytecode if it ever
needs to be read and written. Defining a strategy for pointer
serialization is comparable work.
Do you have a theory or insight that can explain why a situation like
the Java
bytecode VM came to be and why it persists despite your suggestion
that it is
not required or of enough advantage to justify using it (may as well
use Java
source directly)?
Consider the US space shuttle design. It's probably the most
wrong-headed engineering design ever, and it persisted because too many
billions of dollars and careers were invested into it. Nobody could
admit that it was an extremely inefficient and rather crazy design.
A couple NASA engineers have admitted to me privately that they knew
this, but to keep their careers they kept their mouths shut.
That's not answering the question.
Andrei
