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RubyMotion is not a wrapper. It is an implementation of Ruby on the Obj-C runtime. This means that a RubyMotion object is an Obj-C object (for comparison, a Rub

RubyMotion is not a wrapper. It is an implementation of Ruby on the Obj-C runtime. This means that a RubyMotion object is an Obj-C object (for comparison, a Ruby object in MRI is just a C struct). So why would you want to use RubyMotion? Well... * Obj-C, from the very start, was implemented as a strict superset of C. This means that every valid bit of C code must also be valid Obj-C. This places some rather sever limitations on the Obj-C syntax. Ruby does not have this limitation, and neither does RubyMotion. So one reason you might use RubyMotion is to get a cleaner syntax that does the same thing as Obj-C. * The Obj-C runtime is very dynamic. You can create classes on the fly, add methods to them at runtime, move methods around between objects, and create methods dynamically. The Obj-C language makes it nearly impossible to take advantage of any of these features of the Obj-C runtime. So another reason you might use RubyMotion is to get the most out of the Obj-C runtime.

coherentpony 13y ago
That was really informative. Thanks for the breakdown.
sandoze 13y ago
Bullet #2 is so very very wrong. Nice try. I can't speak to the first bullet.
- ics 13y ago
  Please elaborate; I have only minimal experience with ObjC and do not use Ruby in the context of native development, so any well-described counterpoints would be much appreciated. Edit: I obv. didn't write your parent comment. What I meant was that I'm sure others in my position, having read your parent, would appreciate more elaboration from you as well. :)
  - sandoze 13y ago
    Sorry, you're right. It was an off the cuff rebuttal with no substance. Added to the parent comment.
- lukeroberts1990 13y ago
  I think he meant ruby in bullet 2
sandoze 13y ago
In Objective-C we can create methods, properties and classes on the fly using <objc/runtime.h> Here's how to create a property on the fly (great for categories) @dynamic progressView; - (void)setProgressView:(ACProgressView )progressView { objc_setAssociatedObject(self, ACProgressViewKey, progressView, OBJC_ASSOCIATION_RETAIN_NONATOMIC); } - (ACProgressView )progressView { return objc_getAssociatedObject(self, ACProgressViewKey); }
- wrs 13y ago
  You still had to tell the compiler ahead of time about the property. The actual test is more like NSObject obj = [NSObject init]; giveObjectAProperty(obj, @"progressView"); obj.progressView = [NSNumber 42]; Writing giveObjectAProperty may not be "nearly impossible" but it sure isn't easy. And of course the parent is talking about methods, not properties, but...same argument.
  - sandoze 13y ago
    Fair enough. Here's how you'd make that class on the fly: Class mySubclass = objc_allocateClassPair([NSObject class], "MySubclass", 0); Here's how you'd add a description method to a newly created class: static NSString *Description(id self, SEL _cmd){ return [NSString stringWithFormat: @"<%@ %p: foo=%@>",[self class], self, [self foo]]; } // add Description to mySubclass // grab NSObject's description signature so we can borrow it Method description = class_getInstanceMethod([NSObject class], @selector(description)); const char *types = method_getTypeEncoding(description); // now add class_addMethod(mySubclass, @selector(description), (IMP)Description, types); And your iVars: class_addIvar(mySubclass, "foo", sizeof(id), rint(log2(sizeof(id))), @encode(id));
    - 10char 13y ago
      What jballanc is saying is that yes these things are possible in Objective-C, but the technique of doing these tricks in Ruby/Motion is an order of magnitude simpler and idiomatic: klass = Object.const_set "MySubclass", Class.new(Object) klass.send(:attr_accessor, :foo) klass.send(:define_method, "description") { "<#{self.class}: foo=#{self.foo}>" }
mightykan 13y ago
There are a few very well-written wrappers that make utilizing the Obj-C runtime much easier. MAObjCRuntime [1] is a good example of such a wrapper. Look at MACollectionUtilities [2] as an example of how to use MAObjCRuntime. [1]: https://github.com/mikeash/MAObjCRuntime https://github.com/mikeash/MAObjCRuntime [2]: https://github.com/mikeash/MACollectionUtilities https://github.com/mikeash/MACollectionUtilities

coherentpony 13y ago

That was really informative. Thanks for the breakdown.

sandoze 13y ago

Bullet #2 is so very very wrong. Nice try. I can't speak to the first bullet.

ics 13y ago
Please elaborate; I have only minimal experience with ObjC and do not use Ruby in the context of native development, so any well-described counterpoints would be much appreciated. Edit: I obv. didn't write your parent comment. What I meant was that I'm sure others in my position, having read your parent, would appreciate more elaboration from you as well. :)
- sandoze 13y ago
  Sorry, you're right. It was an off the cuff rebuttal with no substance. Added to the parent comment.
lukeroberts1990 13y ago
I think he meant ruby in bullet 2

sandoze 13y ago

In Objective-C we can create methods, properties and classes on the fly using <objc/runtime.h> Here's how to create a property on the fly (great for categories) @dynamic progressView; - (void)setProgressView:(ACProgressView )progressView { objc_setAssociatedObject(self, ACProgressViewKey, progressView, OBJC_ASSOCIATION_RETAIN_NONATOMIC); } - (ACProgressView )progressView { return objc_getAssociatedObject(self, ACProgressViewKey); }

wrs 13y ago
You still had to tell the compiler ahead of time about the property. The actual test is more like NSObject obj = [NSObject init]; giveObjectAProperty(obj, @"progressView"); obj.progressView = [NSNumber 42]; Writing giveObjectAProperty may not be "nearly impossible" but it sure isn't easy. And of course the parent is talking about methods, not properties, but...same argument.
- sandoze 13y ago
  Fair enough. Here's how you'd make that class on the fly: Class mySubclass = objc_allocateClassPair([NSObject class], "MySubclass", 0); Here's how you'd add a description method to a newly created class: static NSString *Description(id self, SEL _cmd){ return [NSString stringWithFormat: @"<%@ %p: foo=%@>",[self class], self, [self foo]]; } // add Description to mySubclass // grab NSObject's description signature so we can borrow it Method description = class_getInstanceMethod([NSObject class], @selector(description)); const char *types = method_getTypeEncoding(description); // now add class_addMethod(mySubclass, @selector(description), (IMP)Description, types); And your iVars: class_addIvar(mySubclass, "foo", sizeof(id), rint(log2(sizeof(id))), @encode(id));
  - 10char 13y ago
    What jballanc is saying is that yes these things are possible in Objective-C, but the technique of doing these tricks in Ruby/Motion is an order of magnitude simpler and idiomatic: klass = Object.const_set "MySubclass", Class.new(Object) klass.send(:attr_accessor, :foo) klass.send(:define_method, "description") { "<#{self.class}: foo=#{self.foo}>" }

mightykan 13y ago

There are a few very well-written wrappers that make utilizing the Obj-C runtime much easier. MAObjCRuntime [1] is a good example of such a wrapper. Look at MACollectionUtilities [2] as an example of how to use MAObjCRuntime. [1]: https://github.com/mikeash/MAObjCRuntime https://github.com/mikeash/MAObjCRuntime [2]: https://github.com/mikeash/MACollectionUtilities https://github.com/mikeash/MACollectionUtilities