It seems most of the examples regarding binding an Objective-C library to c# show methods and properties, but what do you do with instance variables that are declared?
Here's an example of the .h file I'm trying to create a binding for:
#interface NdefRecord : NSObject
{
#public
uint8_t Flags;
NDEF_TNF_Type Tnf;
uint8_t TypeLength;
uint8_t *Type;
uint8_t IdLength;
uint8_t *Id;
uint32_t PayloadLength;
uint8_t *PayloadData;
}
/**
Initialize this record.
- Optional: Since member fields are public, you can also set them directly.
*/
- (id) init:(NDEF_TNF_Type)tnf type:(NSData*)type Id:(NSData*)IdBytes payload:(NSData*)payload;
/**
Parse an NDEF Record from raw bytes.
*/
- (BOOL) parse:(UInt8*)data;
/**
Returns this entire NDEF Record as a byte array.
*/
- (uint32_t) toByteArray:(UInt8*)buffer;
...
#end
In my binding project, things like the parse: method are easy enough to bind, but things like TypeLength and *Type were missed by Objective Sharpie, and nothing I seem to hand create works properly.
In an iOS XCode project, those variables are accessed with syntax like so:
record->TypeLength instead of [record TypeLength] which leads me to believe a simple binding like:
[Export ("TypeLength")]
Byte TypeLength { get; set; }
isn't going to work.
I'm completely stuck on a solution here, so any guidance is much appreciated!
The binding tool does not support accessing internal fields of a class, which is what you are trying to do here.
The only thing you can bind with an [Export] are actual properties and methods.
You need to alter that library to expose properties to those internals.
Related
I have just converted the Filter AU example from apple to use AUMIDIEffectBase class in order to convert it to midi controlled effect.
https://developer.apple.com/library/mac/samplecode/FilterDemo/Introduction/Intro.html
The filter builds however I am getting error in auval tool:
Test MIDI
ERROR: -4 IN CALL MusicDeviceSendMIDI
Anybody has implemented AUMIDIEffectBase successfully?
Any example code?
I was having the same problem today and discovered the issue is in a slightly non-current release of Apple's CoreAudioUtilityClasses, AUMIDIEffectBase class. Due to multiple inheritance the following needed to be added to AUMIDIEffectBase.h so that AUPluginDispatch calls the correct overridden methods.
virtual OSStatus MIDIEvent( UInt32 inStatus,
UInt32 inData1,
UInt32 inData2,
UInt32 inOffsetSampleFrame)
{
return AUMIDIBase::MIDIEvent (inStatus, inData1, inData2, inOffsetSampleFrame);
}
/*! #method SysEx */
virtual OSStatus SysEx( const UInt8 * inData,
UInt32 inLength)
{
return AUMIDIBase::SysEx (inData, inLength);
}
I just pulled the latest from Apple's site: https://developer.apple.com/library/mac/samplecode/CoreAudioUtilityClasses/CoreAudioUtilityClasses.zip and it looks like they already fixed the issue. We both had bad download timing, it seems!
The following line has the error Default argument is not allowed.
public ref class SPlayerObj{
private:
void k(int s = 0){ //ERROR
}
}
Why C++ has no default argument on managed types ?
I would like to know if there is a way to fix this.
It does have optional arguments, they just don't look the same way as the C++ syntax. Optional arguments are a language interop problem. It must be implemented by the language that makes the call, it generates the code that actually uses the default argument. Which is a tricky problem in a language that was designed to make interop easy, like C++/CLI, you of course don't know what language is going to make the call. Or if it even has syntax for optional arguments. The C# language didn't until version 4 for example.
And if the language does support it, how that compiler knows what the default value is. Notable is that VB.NET and C# v4 chose different strategies, VB.NET uses an attribute, C# uses a modopt.
You can use the [DefaultParameterValue] attribute in C++/CLI. But you shouldn't, the outcome is not predictable.
In addition to the precise answer from Hans Passant, the answer to the second part on how to fix this, you are able to use multiple methods with the same name to simulate the default argument case.
public ref class SPlayerObj {
private:
void k(int s){ // Do something useful...
}
void k() { // Call the other with a default value
k(0);
}
}
An alternative solution is to use the [OptionalAttribute] along side a Nullable<int> typed parameter. If the parameter is not specified by the caller it will be a nullptr.
void k([OptionalAttribute]Nullable<int>^ s)
{
if(s == nullptr)
{
// s was not provided
}
else if(s->HasValue)
{
// s was provided and has a value
int theValue = s->Value;
}
}
// call with no parameter
k();
// call with a parameter value
k(100);
I have a bit of a complex program which is giving me this apparently phantom error...
I'll start explaining with the help of this little example program I rigged that can throw my beautiful exception for anyone who runs it.
<!-- language: c# -->
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
namespace so_redux {
static class Program {
[STAThread]
static void Main(){
CS2JS _class=new CS2JS();
}
}//class Program
class CS2JS{
public CS2JS(){
Func<String,Object> js_eval=initJS();
Object cs_ic=initCS();
string xc;
object res;
cs_ic.GetType().GetMethod("init").Invoke(cs_ic,null);
AppDomain.CurrentDomain.SetData("trespasser",cs_ic);
xc=#"function edata(fieldname:String,ival:String):Object{
var sob=System.AppDomain.CurrentDomain.GetData('trespasser');
var v1=sob.GetType().GetField(fieldname).GetValue(sob);
function HASH(s1:String,s2:String):Object{
var q1=sob.GetType().GetField(s1).GetValue(sob);
return q1.ITEM(s2);
}
var v2=v1.ITEM(ival);
return eval(v2);
}
edata('HT','foo');";
res=js_eval(xc);
// var xx;xx=new Hashtable();xx['sda']='1';eval(xx['sda']); OK
}
Func<String,Object> initJS(){
System.CodeDom.Compiler.CodeDomProvider jcc;
System.CodeDom.Compiler.CompilerParameters jcp;
System.CodeDom.Compiler.CompilerResults jcr;
System.Reflection.Assembly jas;
object jis;
string code;
Type t_ii;
code=#"#set #debug(off)
import System;
import System.Collections;
import System.Collections.Generic;
package internal_namespace{class internal_class{
public function internal_method(_code:String):Object{
return eval(_code);
}
}
}";
jcc=Microsoft.JScript.JScriptCodeProvider.CreateProvider("JScript");
jcp=new System.CodeDom.Compiler.CompilerParameters();
jcp.CompilerOptions="/fast-";
jcp.GenerateExecutable=false;
jcp.GenerateInMemory=true;
jcp.IncludeDebugInformation=false;
jcp.ReferencedAssemblies.Add("System.dll");
jcp.ReferencedAssemblies.Add("System.Core.dll");
jcp.WarningLevel=4;
jcr=jcc.CompileAssemblyFromSource(jcp,code);
jas=jcr.CompiledAssembly;
jis=jas.CreateInstance("internal_namespace.internal_class");
t_ii=jas.GetType("internal_namespace.internal_class");
return (s1)=>t_ii.InvokeMember("internal_method",System.Reflection.BindingFlags.InvokeMethod,null,jis,new object[]{s1});
}//initJS
Object initCS(){
var v1= Microsoft.CSharp.CSharpCodeProvider.CreateProvider("CSharp");
System.CodeDom.Compiler.CompilerParameters v2=new System.CodeDom.Compiler.CompilerParameters();
v2.GenerateExecutable=false;
v2.GenerateInMemory=true;
v2.IncludeDebugInformation=false;
v2.WarningLevel=4;
v2.ReferencedAssemblies.Add("System.dll");
v2.ReferencedAssemblies.Add("System.Core.dll");
string _code="public Hashtable2 HT;"+
"public void init(){"+
"HT=new Hashtable2();"+
"HT[\"foo\"]=\"1\";"+
"HT[\"bar\"]=\"HASH('HT','foo')\";"+
"}";
var v3="using System;using System.Collections;using System.Collections.Generic;"+
"namespace internal_namespace{public class Hashtable2:Hashtable{"+
"public Hashtable2():base(){} public Hashtable2(int N):base(N){}"+
"public Object ITEM(Object K){return this[K];} }"+
"[Serializable]public class internal_class{"+
"public internal_class(){}"+
_code+
"\n}}";
var v4=v1.CompileAssemblyFromSource(v2,v3);
var v5=v4.CompiledAssembly;
var v6=v5.GetType("internal_namespace.internal_class");
var v7=v5.CreateInstance("internal_namespace.internal_class");
return v7;
}//initCS
}//class CS2JS
}//namespace so_redux
The exception that is thrown is "index out of bounds", and it's thrown from JScript. The problem? It's that there is no array!
What this code is doing: first a JScript interpreter is initialized by compiling at runtime a class that "exports" an eval (one could do a dll, but in this case I didn't).
Then a C# assembly is compiled, an assembly that "exports" some user code (the variable _code in initCS is originally loaded by reading a text file).
After the initialization of the newly compiled class (the invoking of init()), I need the two assemblies (JScript and C#) to interact, so I need to pass data between them, and I thought of using AppDomain.
Note: in the C# assembly an Hashtable2 is defined because I put in there an ITEM method that one can use in alternative to the common property this[]: in this way debugging is easier (for examply by showing a holy MessageBox when accessing the values).
So, I pass the class instantiated in initCS to JScript, and JScript reads the internal Hashtable (HT). What I need to do is evaluate the data in the Hashtable, because it is supposed to be able to alter itself dynamically.
Everything works fine if I eval a string not taken from the Hashtable -- in the moment I take whatever is in the Hashtable and pass it to eval, then exceptions happen. Attention: the strings are absolutely the same (even comparing them with Equals) and they work, the difference is only from where they come from.
When the JScript function edata evals a string taken from the Hashtable, JScript says "index out of bounds", but as I was saying: I don't see any array there... (and maybe the problem is exactly that, dunno).
I admit I have my limitations in JScript, so if anybody could lend a hand to help understand WTF is going on, I would be really happy.
Temporary solution/workaround splitting the JScript function:
xc=#"function odata(fieldname:String,ival:String):Object{
var sob=System.AppDomain.CurrentDomain.GetData('trespasser');
var v1=sob.GetType().GetField(fieldname).GetValue(sob);
return v1.ITEM(ival);
}
odata('HT','bar');";
res=js_eval(xc);
xc=#"function HASH(s1:String,s2:String):Object{
var sob=System.AppDomain.CurrentDomain.GetData('trespasser');
var q1=sob.GetType().GetField(s1).GetValue(sob);
return q1.ITEM(s2);
}
eval("+res.ToString()+");";
res=js_eval(xc);
but if anybody really got any idea of why is wrong in the first example, please explain me!
I am just trying to compile a bit bigger project using the Visual Studio 2012 Release Candidate, C++. The project was/is compiled using the VS2010 now. (I am just greedy to get the C++11 things, so I tried. :)
Apart of things that I can explain by myself, the project uses the code like this:
ostringstream ostr;
ostr << "The " __FUNCTION__ "() failed to malloc(" << i << ").";
throw bad_alloc(ostr.str().c_str());
The compiler now complains
error C2248: 'std::bad_alloc::bad_alloc' : cannot access private member declared
in class 'std::bad_alloc'
... which is true. That version of constructor is now private.
What was the reason to make that version of constructor private? Is it recommended by C++11 standard not to use that constructor with the argument?
(I can imagine that if allocation failed, it may cause more problems to try to construct anything new. However, it is only my guess.)
Thanks,
Petr
The C++11 Standard defines bad_alloc as such (18.6.2.1):
class bad_alloc : public exception {
public:
bad_alloc() noexcept;
bad_alloc(const bad_alloc&) noexcept;
bad_alloc& operator=(const bad_alloc&) noexcept;
virtual const char* what() const noexcept;
};
With no constructor that takes a string. A vendor providing such a constructor would make the code using it not portable, as other vendors are not obliged to provide it.
The C++03 standard defines a similar set of constructors, so VS didn't follow this part of the standard even before C++11. MS does try to make VS as standard compliant as possible, so they've probably just used the occasion (new VS, new standard) to fix an incompatibility.
Edit: Now that I've seen VS2012's code, it is also clear why the mentioned constructor is left private, instead of being completely removed: there seems to be only one use of that constructor, in the bad_array_new_length class. So bad_array_new_length is declared a friend in bad_alloc, and can therefore use that private constructor. This dependency could have been avoided if bad_array_new_length just stored the message in the pointer used by what(), but it's not a lot of code anyway.
If you are accustomed to passing a message when you throw a std::bad_alloc, a suitable technique is to define an internal class that derives from std::bad_alloc, and override ‘what’ to supply the appropriate message.
You can make the class public and call the assignment constructor directly, or make a helper function, such as throw_bad_alloc, which takes the parameters (and additional scalar information) and stores them in the internal class.
The message is not formatted until ‘what’ is called. In this way, stack unwinding may have freed some memory so the message can be formatted with the actual reason (memory exhaustion, bad request size, heap corruption, etc.) at the catch site. If formatting fails, simply assign and return a static message.
Trimmed example:
(Tip: The copy constructor can just assign _Message to nullptr, rather than copy the message since the message is formatted on demand. The move constructor, of course can just confiscate it :-).
class internal_bad_alloc: public std::bad_alloc
{
public:
// Default, copy and move constructors....
// Assignment constructor...
explicit internal_bad_alloc(int errno, size_t size, etc...) noexcept:
std::bad_alloc()
{
// Assign data members...
}
virtual ~internal_bad_alloc(void) noexcept
{
// Free _Message data member (if allocated).
}
// Override to format and return the reason:
virtual const char* what(void) const noexcept
{
if (_Message == nullptr)
{
// Format and assign _Message. Assign the default if the
// format fails...
}
return _Message;
}
private:
// Additional scalar data (error code, size, etc.) pass into the
// constructor and used when the message is formatted by 'what'...
mutable char* _Message;
static char _Default[];
}
};
//
// Throw helper(s)...
//
extern void throw_bad_alloc(int errno, size_t size, etc...)
{
throw internal_bad_alloc(errno, size, etc...);
}
VERSION 1
class Doh {
private:
static std::map<const std::string, const Doh*> someMap;
std::string stringValue_;
public:
Doh(std::string str) : stringValue_(str) {
Doh::someMap.insert(
std::make_pair<const std::string,const Doh*>
(this->stringValue_,this)
);
}
}
The above was ok with MSVC 2010 but with MSVC 2008 it fails – and I guess it is because the object is not constructed yet when it is inserted in the map (I got a memory access violation).
So, I tried a delayed insertion, which worked:
VERSION 2
Doh(std::string str) : stringValue_(str) {
boost::thread(&Doh::insertIntoTheStaticMap,this);
}
void insertIntoTheStaticMap() {
boost::this_thread::sleep(boost::posix_time::milliseconds(1000));
Doh::someMap.insert(
std::make_pair<const std::string,const Doh*>
(this->stringValue_,this)
);
}
But as you might be able to guess, my intention is to have the static Doh::someMap as a common lookup dictionary.
VERSION 1 didn’t need any thread-safety because I would create all Doh instances in the same thread – in initialization blocks - which would be called by dynamic initializers before I enter main().
But with VERSION 2, the naïve sleep() is neither graceful nor reliable (not to mention, I might need to lock the map before insertion).
What would be a nice KISS approach?
Only potential issue I see is the initialization of the static member, if there are multiple source files. Try guarding it with a function.
class Doh {
private:
static std::map< std::string, Doh * > &get_map() {
static std::map< std::string, Doh * > someMap;
return someMap; // initialize upon first use
}
std::string stringValue_;
public:
Doh(std::string str) : stringValue_(str) {
get_map().insert(
std::make_pair
(this->stringValue_,this)
);
}
};
In neither version is there any sign of init for stringvalue_ - what does the debugger show you about this key when you hit the map insert in version 1 of the code? How is this field set up, and what is its type?
Running this in the debugger for VS2008 should allow you to narrow down the point of failure into the <map> source, I would have thought.