On 2017-08-26 05:40 AM, Danny Niu wrote:
Hi all, I've been struggling finding information on this, so let me open
by asking the following question:
Q1: If primitive types are passed by value and objects by reference when
calling function, where is this characteristic of objects mentioned in
the standard?
Objects aren't "passed by reference" according to the original/usual sense
of that term.
People from https://stackoverflow.com/questions/518000 seems adamant that
ES is a pass-by-value language, so I assumed the value of objects are
their individuality.
The top two answers there both say (more or less) it's pass-by-value, and
for objects, the 'value' is a reference to the object.
So you might wonder why objects are special in this regard. But they aren't:
if you like, you can imagine everything being passed by value, where the
'value' is a reference to the thing.
Q2: What's the rationale if any, to not explicitly require that objects
be viewed as reference when passed as arguments to functions and assigned
to variables.
One reason might be to avoid confusion with the Reference type. Another
reason might be to avoid making a distinction that the spec will never (or
rarely) use.
When you pass a value to a function-parameter or assign a value to a
variable, you are (in spec terms, more or less) binding that value to an
identifier name, i.e., creating an association between the name and the value.
Given that terminology, I don't think it helps to add "reference" to the
description. It's enough to understand that a value can participate in
multiple bindings/associations at the same time. But you're free to imagine
references being involved in the implementation.
-Michael
_______________________________________________
es-discuss mailing list
[email protected]
https://mail.mozilla.org/listinfo/es-discuss
