Calling OBJC runtime from newlisp

[fdb]

I'm trying to call the objc runtime from new lisp (from mac osx10.9) but i've got a problem:

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> (set 'get-class (import "libobjc.dylib" "objc_getClass" "void*" "char*"))
objc_getClass@7FFF9391BF70
> (get-class "NSString")
0

What am i doing wrong here? I was expecting a pointer to the NSString class. The definition of the c function is defined in Apple's Objective-C Runtime Reference:https://developer.apple.com/library/mac/documentation/Cocoa/Reference/ObjCRuntimeRef/Reference/reference.html#//apple_ref/c/func/objc_getClass">//https://developer.apple.com/library/mac/documentation/Cocoa/Reference/ObjCRuntimeRef/Reference/reference.html#//apple_ref/c/func/objc_getClass

objc_getClass

Returns the class definition of a specified class.



id objc_getClass(const char *name)

Parameters

name

The name of the class to look up.

Return Value

The Class object for the named class, or nil if the class is not registered with the Objective-C runtime.

I got the idea from this blog post http://sjhannah.com/blog/?p=219">//http://sjhannah.com/blog/?p=219 which calls the objective-C runtime from Java by using the c-funtions:

objc_msgSend(), to pass messages to objects,

objc_getClass(), to get a pointer to a class and

selector_getUid(), to get the pointer to a selector.

[fdb]

Was probably wrong to use a literal string but this also doesn't work:

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> (set 'nsstring "NSString")
"NSString"
> (get-class nsstring)
0
>


[fdb]

Ok, to answer my own question ;-)

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> (import "/System/Library/Frameworks/Foundation.framework/Foundation")
true
> (get-class "NSString")
140735249161920


Is anyone interested in an newlisp-OBJC bridge? An obvious advantage would be the ability to make native MAC GUI applications, and maybe even IOS applications but i don't know how feasible/desirable that is. I'm going to see how far i can take this, but i don't have a lot of experience in C/ObjC/Cocoa and any help especially regarding memory mgt and proxy's is very welcome!

[TedWalther]

Right on!  Please keep us updated!

[fdb]

Ok, got the basic machinery working to send messages to classes and instances, see below. Next step is to use callbacks for setting delegate's so you could populate a table view from newLISP.

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;;Objective-c bridge

(import "/System/Library/Frameworks/Foundation.framework/Foundation")

(set 'get-class (import "libobjc.dylib" "objc_getClass"))

(set 'get-sel (import "libobjc.dylib" "sel_getUid"))

(set 'msg (import "libobjc.dylib" "objc_msgSend"))

;; principal function sending a message to an instance or class with a variable
;; number of arguments
(define (send-to ptr sel)
(eval (flat (list 'msg ptr (get-sel sel) (args)))))

;; convenience functions can also be made for all classes which will let
;; code look exactly like OBJC syntax (without the ugly square brackets ofcourse)

(define (NSString sel)
(send-to (get-class "NSString") sel (args)))

;; we can then send messsages to classes which almost looks like standard OBJC syntax
;; at least for one variable statements

(set 'my-ns-string(NSString "stringWithUTF8String:" "i'm a pointer to an NSString instance"))

;; converting back from ns-string to normal string, as this is a pointer you need to
;; convert back with get-string. We are sending it to the instance we created with
;; send-to but first make a shortcut to make it almost look like OBJC

(set (sym "_") send-to)

(get-string (_ my-ns-string "UTF8String"))



true

objc_getClass@7FFF9391BF70

sel_getUid@7FFF93920693

objc_msgSend@7FFF9391C080

(lambda (ptr sel) (eval (flat (list 'msg ptr (get-sel sel) (args)))))

(lambda (sel) (send-to (get-class "NSString") sel (args)))

4296018608

(lambda (ptr sel) (eval (flat (list 'msg ptr (get-sel sel) (args)))))

"i'm a pointer to an NSString instance"

[TedWalther]

This is very exciting work.



Also, last night I pulled in some libc functions on my linux box; utimes(2) and link(2).  It was so fast and easy I had a hard time believing it Just Worked.  Thanks to Lutz for the libffi stuff, and the guy who came up with the (struct ..) function.

(import "/lib/x86_64-linux-gnu/libc.so.6" "utime" "int" "char*" "void*")

(import "/lib/x86_64-linux-gnu/libc.so.6" "link" "int" "char*" "char*")

(struct 'utimbuf "long" "long")



(link "file1" "file2")

(when (!= (file-info "file1" 6) (file-info "file3" 6))

      (utime "file3" (pack utimbuf (select (file-info "file1") 5 6))))

Only took 5 minutes. newLisp is letting me get over that nervous feeling of "what is going to go wrong next" every time I try something new.

[fdb]

I'm having problems with a function which returns a struct. To make a window appear on the screen i need an NSRect type, which is defined as a struct:  {{CGFloat,CGFloat},{CGFloat,CGFloat}}. I've imported this function:

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(import "/System/Library/Frameworks/Foundation.framework/Foundation" "NSRectFromString")

NSRectFromString@7FFF8C0561F9
'; but when called

(NSRectFromString "1 2 3 4")

There is nothing, Newlisp halts and i need to restart the shell.



Is there another way to construct this struct and pass it to another function? I've tried

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(struct 'point "double" "double")
(struct 'size "double" "double")
(struct 'rect "point" "size")
(set 'my-rect (pack rect (pack point 100.0 100.0) (pack size 100.0 100.0)))

and pass my-rect but doesn't work

[TedWalther]

NSRectFromString is expecting an NSString class as an argument, but you are passing it a pointer to a regular C string.



Wish I had access to the header files and stuff where this is implemented.  Trying to find the class definition of NSString was tough; how would you use (struct) in newlisp to create an NSString.  Or let's say you call the NSString() initializer that creates it for you, how do you modify its members inside newLISP.

[fdb]

Hi Ted,



you're right NSRecFromString is expecting an NSString, copied the wring line but

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(NSRectFromString (NSString "stringWithUTF8String:" "100,100,100,100"))

doesn't work either. I think it is because it is returning a struct by value and in the import function you cannot define that it returns a struct by value, only pointers, primitive types and c-strings. Not sure if this is a limitation in the libffi library or just not implemented in newLisp.



I found a very nice toolset at ww.f-script.org which does what i try to achieve in newlIsp. Looks like they package structs in NSValue instances and have their own functions written in objective-c but i was hoping that i could interact with the runtime without an intermediate layer.

[fdb]

Solved the returning of a struct

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(struct 'Point "double" "double")
(struct 'Rect "point" "point")
(import "/System/Library/Frameworks/Foundation.framework/Foundation" "NSRectFromString" "Rect" "void*")

So you can define the struct as a return type, was not mentioned in the documentation for import , so please add this.

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(setq myrect (NSRectFromString (@@ "100 200 50 20")))

((100 200) (50 20))

[fdb]

I've changed my message sending function to • (alt 8) and can alternate in methods and value and it looks nice have imported some constants and such and works fine except for structs..(i think)  i can't get the following code to work

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(setq window (•(• NSWindow "alloc") "initWithContentRect:" (@rect "0  0 200 200") "styleMask:" NSTitledWindowMask "backing:" NSBackingStoreBuffered "defer:" NO))
(• window "orderFront:" nil)


2014-09-14 19:58:48.249 newlisp[1499:507] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Error (1000) creating CGSWindow'

*** First throw call stack:

(

   0   CoreFoundation                      0x00007fff87c5025c __exceptionPreprocess + 172

   1   libobjc.A.dylib                     0x00007fff82d90e75 objc_exception_throw + 43

   2   CoreFoundation                      0x00007fff87c5010c +[NSException raise:format:] + 204

   3   AppKit                              0x00007fff89d0cf81 _NXCreateWindowWithStyleMask + 366

   4   AppKit                              0x00007fff89d0cd7d _NSCreateWindow + 64

   5   AppKit                              0x00007fff89bc572c -[NSWindow _commonAwake] + 2963

   6   AppKit                              0x00007fff89bd3b63 -[NSWindow _reallyDoOrderWindow:relativeTo:findKey:forCounter:force:isModal:] + 1121

   7   AppKit                              0x00007fff89bd3460 -[NSWindow _doOrderWindow:relativeTo:findKey:forCounter:force:isModal:] + 786

   8   AppKit                              0x00007fff89bd30e0 -[NSWindow orderWindow:relativeTo:] + 162

   9   newlisp                             0x00000001000262c0 newlisp + 156352

   10  newlisp                             0x000000010000539b newlisp + 21403

   11  newlisp                             0x000000010000667a newlisp + 26234

   12  newlisp                             0x000000010000530f newlisp + 21263

   13  newlisp                             0x0000000100005e33 newlisp + 24115

   14  newlisp                             0x000000010000530f newlisp + 21263

   15  newlisp                             0x0000000100009006 newlisp + 36870

   16  newlisp                             0x000000010000537e newlisp + 21374

   17  newlisp                             0x0000000100009e6d newlisp + 40557

   18  newlisp                             0x000000010000b3c2 newlisp + 46018

   19  newlisp                             0x000000010000bc57 newlisp + 48215

   20  newlisp                             0x0000000100000d3c newlisp + 3388

)

libc++abi.dylib: terminating with uncaught exception of type NSException

The runtime also complains about the style mask, but the message can differ every time i invoke the init method.

Lutz could you help here? After some googling i found that it may be the FFI: big  structs 'are not passed on the stack' or something, i'm really out of my depth here and any help is much appreciated.

[Lutz]

The fact, that the error looks different each time, makes me think that already reclaimed memory is overwritten.



I am not at all familiar with Objective C and how it manages memory but could imagine, that some of the memory allocated for structures by Objc—C  (coming back as structure return values) is collected soon afterwards by Objective C. What might help is: not to nest newLISP expressions too much but do assignments first. This way memory crated in Obc-C functions gets copied/created and managed inside newLISP. E.g.:

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(setq theRect (@rect "0  0 200 200"))
(setq dotAlloc (• NSWindow "alloc"))
(setq window (• dotAlloc  "initWithContentRect:" theRect "styleMask:" NSTitledWindowMask "backing:" NSBackingStoreBuffered "defer:" NO))


.. but this is just a wild guess ;)



Ps: I assume that @rect and • are functions imported from Objective C

Ps: on second thought if @rect and • return just some integer handle numbers/addresses it won't make a difference and still crash

[fdb]

Well i'm almost there (i hope)

The crashing is because you need to instantiate an NSApplication first which generates an event loop and takes care of events in the Window.  So this tiny ObjC program works fine, the application starts and displays and empty window.

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#import <AppKit/AppKit.h>
#import <Foundation/Foundation.h>
int main ()
{
    [NSApplication sharedApplication];
    [NSApp setActivationPolicy:NSApplicationActivationPolicyRegular];
    NSRect myrect = NSRectFromString(@"20 20 200 200");
    id window = [[NSWindow alloc]   initWithContentRect:myrect
                                              styleMask:3
                                                backing:NSBackingStoreBuffered
                                                  defer:NO];
   
    [window orderFront:nil];
    [NSApp activateIgnoringOtherApps:YES];
    [NSApp run];
    return 0;
}
However my newLisp program which (should do) the same starts the application fine, but it doesn't draw a window (or it is so tiny i can't see it...

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(setq nsapp (• NSApplication "sharedApplication"))
(• nsapp "setActivationPolicy:" NSApplicationActivationPolicyRegular)
(set 'arect (@rect "20 20 200 200"))
(set 'amask NSTitledWindowMask)
(set 'abacking NSBackingStoreBuffered)
(set 'adefer NO)
(setq awind (• NSWindow "alloc"))
(setq window (• awind "initWithContentRect:" arect
        "styleMask:" amask
"backing:" NSBackingStoreBuffered
"defer:" adefer))
(• window "makeKeyAndOrderFront:" nil)
(• nsapp "activateIgnoringOtherApps:" YES)
(• nsapp "run")

I still suspect that the rect struct isn't passed correctly, for the other values i also tested with 'packing' them but that didn't help either, Does anyone know how to test that the rect struct is passed correctly?

[Lutz]

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   [window orderFront:nil];
    [NSApp activateIgnoringOtherApps:YES];


and

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(• window "makeKeyAndOrderFront:" nil)
(• nsapp "activateIgnoringOtherApps:" YES)


for sure nil and YES are not the same in newLISP and Objective C. In case of YES the contents of the newLISP variable YES will be passed. Somewhere you would have to set YES to the same value it has in Objective C. Probably you can find out from the header files. The same is true for nil, you probably have to define a NIL in newLISP for usage with Objective C:

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(set 'NIL <whatever Obj-C wants here>) ; for usage with Obj-C


I guess somewhere in the Obj-C docs or header files you can find the value.

[fdb]

Hi Lutz , yes i've defined them in newLisp, they're enum's. So to clarify this works:

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#import <AppKit/AppKit.h>
#import <Foundation/Foundation.h>
int main ()
{
    [NSApplication sharedApplication];
    [NSApp setActivationPolicy:NSApplicationActivationPolicyRegular];
    NSRect myrect = NSRectFromString(@"20 20 200 200");
    id window = [[NSWindow alloc]   initWithContentRect:myrect
                                              styleMask:1
                                                backing:2
                                                  defer:0];
   
    [window orderFront: window];
    [NSApp activateIgnoringOtherApps:1];
    [NSApp run];
    return 0;
}
and the same in newLisp doesn't

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(setq nsapp (• NSApplication "sharedApplication"))
(• nsapp "setActivationPolicy:" NSApplicationActivationPolicyRegular)
(set 'rect (@rect "20 20 200 200"))
(set 'mask NSTitledWindowMask)
(set 'backing NSBackingStoreBuffered)
(set 'defer 0)
(setq awind (• NSWindow "alloc"))
(setq window (• awind "initWithContentRect:" rect "styleMask:" 1 "backing:" 2 "defer:" 0))
(• window "orderFront:" window)
(• nsapp "activateIgnoringOtherApps:" 1)
(• nsapp "run")