Class JSADDBRANDSEXP

Remarks

When instantiating an object of a JSClass, if the class happens to use private methods, we must register a brand (a unique symbol) with it. This brand check ensures that the private symbol/method being referenced is valid in the scope. If the brand of the object instance and the private method being referenced fail the brand check, a runtime error is thrown.

add a private brand field to 'home_obj' if not already present and if obj is != null add a private brand to it

One may imagine this to be a way to push the class encapsulation check to the runtime; contrary to languages like Java/C++ where it might be a static compile time check.

Action

[0] JSADDBRAND (obj, homeObj)
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Trigger

class Test { #foo() { } }
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Further

This instruction is added at the end of the class property init closure (a closure used to initialize the fields of a new object instance). This may be skipped, if there are no private symbols or the check can be proved to be redundant statically.

Structure

• ARG(obj): The object instance.

• ARG(homeObj): The home object.