Merged with Why do I get no warning when protocol methods are not specified?.
I'm using Xcode 4, have a simple class interface defined and I added NSTableViewDelegate and NSTableViewDataSource protocols to the interface definition. I.e,
#interface foo : NSObject < NSTableViewDelegate, NSTableViewDataSource>
In my build settings, I have confirmed that the option "Incomplete Objective-C Protocols" warning is enabled (for Debug/Any Architecture etc) and I should get a compile time warning for the non-optional methods required for the NSTableViewDataSource protocol. However, I get no warnings at all but then at runtime I see the message in the log that the methods aren't defined.
Anyone know why?
Related
I am using the checkerFramework gradle plugin to statically analyze nullness and tainting in my code. When I run the checker via gradle, only one of my classes are properly checked. All the other classes return with the ambiguous error about the checker not running:
error: [type.checking.not.run] NullnessChecker did not run because of a previous error issued by ja
vac
public class Main {
^
The manual linked does not metion what potentially causes this. I had some #Nullable annotations prepended to some static instance variables of the primary class I am using, but undoing those did not fix the issue.
My build.gradle is set up like so:
plugins {
// Checker Framework pluggable type-checking
id 'org.checkerframework' version '0.6.3'
}
checkerFramework {
checkers = [
'org.checkerframework.checker.nullness.NullnessChecker',
'org.checkerframework.checker.tainting.TaintingChecker'
]
}
apply plugin: 'org.checkerframework'
Where do I find more detail on this error?
You didn't show the full javac output. The relevant errors should be just above the error: [type.checking.not.run] line that you did show.
The Checker Framework runs as a plugin to javac. When javac issues an error in one class (including any Checker Framework error), javac may or may not process other classes. Unfortunately, there is no good way for a user to predict how far javac will get. Your best bet is to focus on the code that matters most to you, and resolve each error in turn before proceeding to other classes.
I have a Clojurescript program running in the browser.
It imports a number of libraries, and then I want to allow the user to enter some small clojurescript "glue-code" that calls those libraries.
I can see (from https://cljs.github.io/api/cljs.js/eval) that you call eval with four arguments, the first being the state of the environment, which is an atom. But can I actually turn my current environment with all the functions I've required from elsewhere, into an appropriate argument to eval?
Update :
I thought that maybe I could set the namesspace for the eval using the :ns option of the third, opts-map, argument. I set it to the namespace of my application :
:ns "fig-pat.core"
But no difference.
Looking at the console, it's definitely the case that it's trying to do the evaluation, but it's complaining that names referenced in the eval-ed code are NOT recognised :
WARNING: Use of undeclared Var /square
for example. (square is a function I'm requiring. It's visible in the application itself ie. the fig-pat.core namespace)
I then get :
SyntaxError: expected expression, got '.'[Learn More]
Which I'm assuming this the failure of eval-ed expression as a whole.
Update 2 :
I'm guessing this problem might actually be related to : How can I get the Clojurescript namespace I am in from within a clojurescript program?
(println *ns*)
is just printing nil. So maybe Clojurescript can't see its own namespace.
And therefore the :ns in eval doesn't work?
Calling eval inside a clojurescript program is part of what is called "self-hosted clojurescript".
In self-hosted clojurescript, namespaces are not available unless you implement a resolve policy. It means that have to let the browser know how to resolve the namespace e.g. loads a cljs file from a cdn.
It's not so trivial to implement namespace resolving properly.
This is explained in a cryptic way in the docstring of load-fn from cljs.js namespace.
Several tools support namespaces resolving in self-host cljs running in the browser e.g Klipse and crepl
Is there a way to pass any meaningful message, not “std::exception” to the promise’s fail callback? In the sources I found the following “void FB::variantDeferred::reject(std::exception e) const” specification. It seems when reject is called with any exception derived from std::exception the slicing happens and the right exception’s message is lost. Is there any workaround but to pass error through success callback?
std::exception is simply a base class for creating exceptions in C++. You can use a number of different methods to pass a specific string back; for example, you could throw a std::runtime_error, which accepts a message.
You could also subclass std::exception and provide an implementation of std::exception::what which returns a useful string representation of what you want.
FireBreath 2.0 will use the error message from e.what() when it creates the Error object. You can find this in the code, if you're curious how that works:
NPAPI
ActiveX
FireWyrm (used for Native Messaging)
In CUDA we can get to know about errors simply by checking return type of functions such as cudaMemcpy(), cudaMalloc() etc. which is cudaError_t with cudaSuccess. Is there any method available in JCuda to check error for functions such as cuMemcpyHtoD(), cuMemAlloc(), cuLaunchKernel() etc.
First of all, the methods of JCuda (should) behave exactly like the corresponding CUDA functions: They return an error code in form of an int. These error codes are also defined in...
the cudaError class for the Runtime API
the CUresult class for the Driver API
the cublasStatus class for JCublas
the cufftResult class for JCufft
the curandStatus class for JCurand
the cusparseStatus class for JCusparse
and are the same error codes as in the respective CUDA library.
All these classes additionally have a static method called stringFor(int) - for example, cudaError#stringFor(int) and CUresult#stringFor(int). These methods return a human-readable String representation of the error code.
So you could do manual error checks, for example, like this:
int error = someCudaFunction();
if (error != 0= {
System.out.println("Error code "+error+": "+cudaError.stringFor(error));
}
which might print something like
Error code 10: cudaErrorInvalidDevice
But...
...the error checks may be a hassle. You might have noticed in the CUDA samples that NVIDIA introduced some macros that simplify the error checks. And similarly, I added optional exception checks for JCuda: All the libraries offer a static method called setExceptionsEnabled(boolean). When calling
JCudaDriver.setExceptionsEnabled(true);
then all subsequent method calls for the Driver API will automatically check the method return values, and throw a CudaException when there was any error.
(Note that this method exists separately for all libraries. E.g. the call would be JCublas.setExceptionsEnabled(true) when using JCublas)
The samples usually enable exception checks right at the beginning of the main method. And I'd recommend to also do this, at least during the development phase. As soon as it is clear that the program does not contain any errors, one could disable the exceptions, but there's hardly a reason to do so: They conveniently offer clear information about which error occurred, whereas otherwise, the calls may fail silently.
I'm using Xcode 4, have a simple class interface defined and I added NSTableViewDelegate and NSTableViewDataSource protocols to the interface definition. I.e,
#interface foo : NSObject < NSTableViewDelegate, NSTableViewDataSource>
In my build settings, I have confirmed that the option "Incomplete Objective-C Protocols" warning is enabled (for Debug/Any Architecture etc) and I should get a compile time warning for the non-optional methods required for the NSTableViewDataSource protocol. However, I get no warnings at all but then at runtime I see the message in the log that the methods aren't defined.
Anyone know why?
If you look at Apple's NSTableView.h, you'll se this:
#protocol NSTableViewDataSource <NSObject>
#optional
/* Required Methods
*/
- (NSInteger)numberOfRowsInTableView:(NSTableView *)tableView;
- (id)tableView:(NSTableView *)tableView objectValueForTableColumn:(NSTableColumn *)ta bleColumn row:(NSInteger)row;
...
So the comment and the documentation claim that the methods are required, but the code says they're not. The compiler ultimately ignores all comments and documentation happily altogether. ;) Hence you're not getting a compiler warning.
I guess it was their intention to make these two methods required (would make lots of sense), but discovered that lots of their own code relies on it being an informal protocol still. So instead of the headache of changing all the legacy code, I assume they decided to not make them required just yet. I'd expect this to change in Lion though.