Re: How to add named variables to a SpiderMonkey context?

Yes, you'll probably want to be defining properties on the global.

Note that from C++, usually you'll want the JS_DefineProperty family of
functions, not JS_SetProperty. Setting a property means looking up the
prototype chain to see where a value is defined, setting its value if it
is found, and otherwise defining the property with default flags.
Defining a property means the much more straightforward "I want property
X on object O, with this value, with these flags". JS_SetProperty is
only useful for emulating a `somevar = somevalue` statement in JS.


On 7/15/20 11:31 AM, James Stortz wrote:
> The C++ engine is just the underlying implementation of the JS
> paradigm, so, the logic will be the same as your script, but low
> level.
>
> 1 Create the variable handle
> 2 Assign it a value (such as object, array, function, string, etc.)
> 3 Define it on an object (such as the global scope)
>
> You will have to follow these steps to define each and every property
> or method.
>
> You can also set flags such as read only, permanent, enumerable, etc.
> You can also define prototypes and instantiate objects from those
> types instead of just generic objects.
>
> see:
>
> JS::RootedValue and (.setString or .setObject or .setBoolean or ...)
>
> JS_DefineFunction or JS_SetFunction
> JS_DefineProperty or JS_SetProperty
> JS_DefineElement or JS_SetElement
>
> and:
>
> JSPROP_PERMANENT and ...
> JSClass and JSClassOps and JS_InitClass
>
> On 7/15/20, Kent Williams <[email protected]> wrote:
>> This seems super-obvious to me but it's a part of using the SpiderMonkey
>> C++ API I haven't had to use before.
>>
>> 1. How do you add named objects to an interpreter context? Like there
>> should be functions like
>>
>> JS_AddNamedObject(JSContext *cx, char *name, JS::HandleObject obj);
>> JS_AddNamedValue(JSContext *cx, char *name, JS::HandleValue obj);
>>
>> 2. Similarly there should be functions to look up values in the
>> Interpreter context by name.
>> JS_GetNamedValue(JSContext *cx, char *name, JS::HandleValue &value);
>>
>> Am I just missing where this stuff is in the API?
>>
>>
>> USE CASE: I want replace making assignments by building up a script and
>> then evaluating it, to doing the assignment directly with C++ api.
>>
>> It should faster to not parse and execute a script, and it would also
>> get rid of a bunch of escaping you need to do for JS code to interpret
>> the value literals properly.
>>
>> _______________________________________________
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>> [email protected]
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>>
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