This directory contains a sample Objective-C bridge that shows you how to bind a new language to Gravity.
main.m file contains a standard main function that loads a Gravity source main.gravity and executes it.
The core function is a C function:
void objc_register (gravity_vm *VM);
used to register the ObjC class to the current Gravity VM instance.
ObjC is a dynamic language that offers a rich set of runtime reflection features.
An ObjC class can be scanned using the objc/runtime.h API.
Using these APIs, we can construct a Gravity class that acts as a bridge between the ObjC runtime and the Gravity runtime with access to all its methods and properties.
A more manual approach should be followed for other languages that do not offer runtime introspection features (if it is not possible to extract methods and properties at runtime). A manual approach could be header extraction or a text file that contains all the necessary information to reconstruct the class (and that it must be manually parsed).
Using the Objective-C binding is really easy. Basically it means to execute the ObjC.register method and then you can use any ObjC method/property. For example:
// to be later registered at runtime
extern var ObjC;
// list here all the ObjC classes to register and use
var Alert
func loadObjCClasses() {
Alert = ObjC.register("NSAlert")
}
func main() {
loadObjCClasses();
// ObjC Hello World
var alert = Alert()
alert.messageText = "Hello World"
alert.informativeText = "Hello from Gravity!"
alert.runModal()
return 0
}Result in macOS 11.2 is a modal dialog:
Some users asked for a way to bind Java to Gravity. I am not a Java expert, but I am sure that it can be done and the process can be fully automated.
- To build a Gravity class you can use the Java reflection API
- To execute Java code from C, the JNI can be used
Some useful Java related links: