I am working with c++ cli.
Writing "System::Collections::Generic::IList" for IList every time is difficult, makes code long and difficult to read.
It is dicussed here enter link description here
using IList = System::Collections::Generic::IList; // Didn't work.
typedef System::Collections::Generic::IList Ilist; // Didn't work also.
How can I make alias for it?
I'm not sitting at a compiler, but I'm guessing that the typedef doesn't work because IList isn't the full name of that type: The full name would be IList<some type>. You should be able to do
typedef System::Collections::Generic::IList<String^> IStringList;.
Since it doesn't look like you want to change the name of IList to something else, using namespace System::Collections::Generic; should do the trick.
The code below compiled. But that is not what i am looking for. type in angle brackets can be integer, string or any class list. But in some context it works.
typedef System::Collections::Generic::IList<int>^ IintList1;
using IintList2 = System::Collections::Generic::IList<int>^;
IintList1 list1 = nullptr;
list1->Add(1);
IintList2 list2 = nullptr;
list2->Add(2);
Related
I have an error that used to look like this in Objective-C
NSString * const JKConfigurationErrorDomain;
typedef NS_ENUM(NSInteger, JKConfigurationCode) {
JKConfigurationCodeUnknown,
JKConfigurationCodeSomethingBad,
JKConfigurationCodeParsing,
};
Now, this is ugly to use in Swift. But since Swift 4, we can use NSErrorDomain and NS_ERROR_ENUM to make the imported error much nicer in Swift:
NSErrorDomain const JKConfigurationErrorDomain;
typedef NS_ERROR_ENUM(JKConfigurationErrorDomain, JKConfigurationCode) {
JKConfigurationCodeUnknown,
JKConfigurationErrorSomethingBad,
JKConfigurationErrorParsing,
};
This means I can now do stuff in Swift like this:
if let myError = error as? JKConfigurationError, myError.code = .somethingBad {
// handle it
}
instead of having to cast error to NSError, then check its .domain then look at the .code which is an integer, etc.
So far, so good. But my library is called JKConfiguration and there is already a JKConfiguration object (the center piece of the library) in there and as soon as I start using JKConfiguration anywhere in the library code I get an error:
'JKConfiguration' is ambiguous for type lookup in this context
I don't get it, why? What does NSErrorDomain or NS_ERROR_ENUM do such that the type lookup becomes ambiguous and how can I fix it?
What I tried already:
use NS_SWIFT_NAME on the NS_ERROR_ENUM typedef and rename it to something else. Looking at the generated Swift header, the rename works, but doesn't solve the issue
Change the name of the error domain (and thus of the generated error type in Swift). Seems to work according to the generated Swift header, but the issue still persists. Why is that?
The issue is not, as I initially thought, in the name of the error domain. Nor is it a problem with the library name. It’s a problem of the error enum‘s name, in the example above: JKConfigurationCode.
What the Compiler does for the enum cases of an NS_ERROR_ENUM is two-fold:
use the name of the enum and remove that prefix from all enum cases before importing them to swift
create an enum with the given name to hold those cases. If the given name ends with Code remove that suffix.
So that last part is the issue. It means that NS_ERROR_ENUM(AnyDomainName, JKConfigurationCode) generates an enum in Swift to hold the error codes with the name JKConfiguration (without the Code) prefix. But that type already exists in my example, which leads to the ambiguity.
So the solution is to change
NS_ERROR_ENUM(JKConfigurationErrorDomain, JKConfigurationCode)
to
NS_ERROR_ENUM(JKConfigurationErrorDomain, JKConfigurationSomethingCode)
Or similar.
Don’t forget to update all the prefixes of your enum cases though, as it seems the compiler won’t find them if the prefixes don’t match the enum name.
Why doesn’t NS_SWIFT_NAME work to rename the enum?
Best I can tell, NS_SWIFT_NAME causes the type to be renamed but not the cases. This leads to an empty type (Swift chooses a struct in that case) being generated for the error code as Swift doesn’t seem to find the cases. And the original container for the enum cases still has the offending name.
I am reading Apple's recently (Dec 5, 2013) updated sample code for camera control using AV Foundation (here is the link). And I come across the following lines in the file AVCamViewController.m which I don't understand.
static void * CapturingStillImageContext = &CapturingStillImageContext;
static void * RecordingContext = &RecordingContext;
static void * SessionRunningAndDeviceAuthorizedContext = &SessionRunningAndDeviceAuthorizedContext;
What does it mean to assign the pointer of itself? Why do we need this?
Update (2015-10-02): Now the AVCam is updated and rename to AVCam-iOS, if you are still insterest in this code AVCamViewController.m.
Well, so idea for these constants is to have some unique value, that will not repeat anywhere in the program, but we don't really care about its content.
Now, instead of coming up with some random string/number etc, we just create a pointer, and put its address as content, this way it's unique and the code is simple is nice :)
I want to pass a managed array from VB.NET to a function in a VC++ project. How would I declare my C++ function and how would I use the array when I'm inside it? Specifically, I want to make VB compatible functions like the one below, which is written in plain old C.
void Vcopy(double *A, double *B)
{
int n;
for(n=0;n<3;n++)
{
B[n]=A[n];
}
}
Maybe some kind soul could convert this to something that would play nicer with VB. Thanks!
Can the C++ method be managed, e.g., C++/CLI ?
If so, then:
void Vcopy(array<double> ^A, array<double> ^B)
By the way, the rest of the method should be identical, provided that the size is 3 - otherwise use A->Length and B->Length.
I building Wrapper in C++/CLI for C Static library to be used in .NET application through C#
I have function like this in C
long My_COM_Interface( PVOID hDevice,IUnknown **pUnknown);
How to declare IUnknown ** in C++/CLI
for first argument I am using IntPtr but Not able to find out the Replacement for IUknown.
I have another COM Data type GUID in another function this is also an issue for me.
Please Help me find the relacement for data type IUnknown and GUID.
There is no replacement.
C++/CLI understands native types just fine. Include the right header files, and you can use IUnknown* like always.
I'd refer to the APIs, e.g.
public static IntPtr GetIUnknownForObject(Object o);
This API can simply be used from C++/CLR and suggests you should use IntPtr^
try using parameter like;
ref object pUnknown
and use it like
MyObject o = pUnknown as MyObject
Is there a simple way to check the type of an object? I need something along the following lines:
MyObject^ mo = gcnew MyObject();
Object^ o = mo;
if( o->GetType() == MyObject )
{
// Do somethine with the object
}
else
{
// Try something else
}
At the moment I'm using nested try-catch blocks looking for System::InvalidCastExceptions which feels ugly but works. I was going to try and profile something like the code above to see if it's any faster/slower/readable but can't work out the syntax to even try.
In case anyone's wondering, this comes from having a single queue entering a thread which supplied data to work on. Occasionally I want to change settings and passing them in via the data queue is a simple way of doing so.
You can use MyObject::typeid in C++/CLI the same way as typeof(MyObject) is used in C#. Code below shamelessly copied from your question and modified ...
MyObject^ mo = gcnew MyObject();
Object^ o = mo;
if( o->GetType() == MyObject::typeid )
{
// Do somethine with the object
}
else
{
// Try something else
}
You should check out How to: Implement is and as C# Keywords in C++:
This topic shows how to implement the functionality of the is and as C# keywords in Visual C++.
edit: I will leave this here. But this answer is for C++. Probably not even slightly related to doing this for the CLI.
You need to compile with RTTI(Run Time Type Information) on. Then look at the wikipedia article http://en.wikipedia.org/wiki/Run-time_type_information and search google for RTTI. Should work for you.
On the other hand you might want to have a virtual base class for all your data classes with a member variable that describes what type it is.