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Q&A cannot initialize a variable of type 'CFDictionaryRef'

Background story: I'm on mac OS 11.6 and would like to access an identifier for the current space/desktop from the command line. I found a helpful article at https://ianyh.com/blog/identifying-spac...

1 answer · posted 3y ago by foobar‭ · edited 3y ago by Alexei‭

Question error-handling macos-big-sur macos

#3: Post edited by

Alexei‭ · 2022-01-25T08:26:18Z (almost 3 years ago)
added relevant tag

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error-handling macos-big-sur

error-handling macos-big-sur macos

#2: Post edited by

foobar‭ · 2022-01-24T21:30:57Z (almost 3 years ago)

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Background story: I'm on mac OS 11.6 and would like to access an identifier for the current space/desktop from the command line. I found a helpful article at https://ianyh.com/blog/identifying-spaces-in-mac-os-x/ which describes a strategy to compare the output of `defaults read com.apple.spaces` with the list of windows on the current space. I don't really know how to puzzle together all the code fragments from this site, so I kept searching and found this implementation: https://gist.github.com/camillol/1129406
I tried to compile it with `clang++ spaceutil.c`, but get the following error:
```
clang: warning: treating 'c' input as 'c++' when in C++ mode, this behavior is deprecated [-Wdeprecated]
spaceutil.c:20:25: error: cannot initialize a variable of type 'CFDictionaryRef' (aka 'const __CFDictionary *') with an rvalue of type 'const void *'
CFDictionaryRef windict = CFArrayGetValueAtIndex(windows, i);
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
spaceutil.c:21:21: error: cannot initialize a variable of type 'CFNumberRef' (aka 'const __CFNumber *') with an rvalue of type 'const void *'
CFNumberRef spacenum = CFDictionaryGetValue(windict, kCGWindowWorkspace);
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
spaceutil.c:21:62: warning: 'kCGWindowWorkspace' is deprecated: first deprecated in macOS 10.8 - No longer supported [-Wdeprecated-declarations]
CFNumberRef spacenum = CFDictionaryGetValue(windict, kCGWindowWorkspace);
^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/System/Library/Frameworks/CoreGraphics.framework/Headers/CGWindow.h:106:30: note: 'kCGWindowWorkspace' has been explicitly marked deprecated here
CG_EXTERN const CFStringRef kCGWindowWorkspace
^
1 warning and 2 errors generated.
```
My clang++ version is
```
clang++ --version
Apple clang version 13.0.0 (clang-1300.0.29.30)
Target: arm64-apple-darwin20.6.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
```
Any pointers how to fix this error?

Background story: I'm on mac OS 11.6 and would like to access an identifier for the current space/desktop from the command line. I found a helpful article at https://ianyh.com/blog/identifying-spaces-in-mac-os-x/ which describes a strategy to compare the output of `defaults read com.apple.spaces` with the list of windows on the current space. I don't really know how to puzzle together all the code fragments from this site, so I kept searching and found this implementation: https://gist.github.com/camillol/1129406 :
```
#include <unistd.h>
#include <CoreServices/CoreServices.h>
#include <ApplicationServices/ApplicationServices.h>
typedef int CGSConnection;
extern OSStatus CGSGetWorkspace(const CGSConnection cid, int *workspace);
extern OSStatus CGSSetWorkspace(const CGSConnection cid, int workspace);
extern CGSConnection _CGSDefaultConnection(void);
int get_space_id(void);
void set_space_by_index(int space);
int get_space_id(void)
{
int space;
CFArrayRef windows = CGWindowListCopyWindowInfo( kCGWindowListOptionOnScreenOnly, kCGNullWindowID );
CFIndex i, n;
for (i = 0, n = CFArrayGetCount(windows); i < n; i++) {
CFDictionaryRef windict = CFArrayGetValueAtIndex(windows, i);
CFNumberRef spacenum = CFDictionaryGetValue(windict, kCGWindowWorkspace);
if (spacenum) {
CFNumberGetValue(spacenum, kCFNumberIntType, &space);
return space;
}
}
return -1;
}
void set_space_by_index(int space)
{
CFNotificationCenterRef nc = CFNotificationCenterGetDistributedCenter();
CFStringRef numstr = CFStringCreateWithFormat(NULL, nil, CFSTR("%d"), space);
CFNotificationCenterPostNotification(nc, CFSTR("com.apple.switchSpaces"), numstr, NULL, TRUE);
}
int main (int argc, char * const argv[])
{
int useCGS = 0, ch, space;
while ((ch = getopt(argc, argv, "-c")) != -1) {
switch (ch) {
case 'c':
useCGS = 1;
break;
}
}
argc -= optind;
argv += optind;
if (argc > 0) {
space = atoi(argv[0]);
if (useCGS) CGSSetWorkspace(_CGSDefaultConnection(), space);
else set_space_by_index(space);
} else {
if (useCGS) CGSGetWorkspace(_CGSDefaultConnection(), &space);
else space = get_space_id();
printf("%d\n", space);
}
return 0;
}
```
I tried to compile it with `clang++ spaceutil.c`, but get the following error:
```
clang: warning: treating 'c' input as 'c++' when in C++ mode, this behavior is deprecated [-Wdeprecated]
spaceutil.c:20:25: error: cannot initialize a variable of type 'CFDictionaryRef' (aka 'const __CFDictionary *') with an rvalue of type 'const void *'
CFDictionaryRef windict = CFArrayGetValueAtIndex(windows, i);
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
spaceutil.c:21:21: error: cannot initialize a variable of type 'CFNumberRef' (aka 'const __CFNumber *') with an rvalue of type 'const void *'
CFNumberRef spacenum = CFDictionaryGetValue(windict, kCGWindowWorkspace);
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
spaceutil.c:21:62: warning: 'kCGWindowWorkspace' is deprecated: first deprecated in macOS 10.8 - No longer supported [-Wdeprecated-declarations]
CFNumberRef spacenum = CFDictionaryGetValue(windict, kCGWindowWorkspace);
^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/System/Library/Frameworks/CoreGraphics.framework/Headers/CGWindow.h:106:30: note: 'kCGWindowWorkspace' has been explicitly marked deprecated here
CG_EXTERN const CFStringRef kCGWindowWorkspace
^
1 warning and 2 errors generated.
```
My clang++ version is
```
clang++ --version
Apple clang version 13.0.0 (clang-1300.0.29.30)
Target: arm64-apple-darwin20.6.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
```
Any pointers how to fix this error?

#1: Initial revision by

foobar‭ · 2022-01-24T11:12:43Z (almost 3 years ago)

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cannot initialize a variable of type 'CFDictionaryRef'

Background story: I'm on mac OS 11.6 and would like to access an identifier for the current space/desktop from the command line. I found a helpful article at https://ianyh.com/blog/identifying-spaces-in-mac-os-x/ which describes a strategy to compare the output of `defaults read com.apple.spaces` with the list of windows on the current space. I don't really know how to puzzle together all the code fragments from this site, so I kept searching and found this implementation: https://gist.github.com/camillol/1129406

I tried to compile it with `clang++ spaceutil.c`, but get the following error:

``` 
clang: warning: treating 'c' input as 'c++' when in C++ mode, this behavior is deprecated [-Wdeprecated]
spaceutil.c:20:25: error: cannot initialize a variable of type 'CFDictionaryRef' (aka 'const __CFDictionary *') with an rvalue of type 'const void *'
        CFDictionaryRef windict = CFArrayGetValueAtIndex(windows, i);
                        ^         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
spaceutil.c:21:21: error: cannot initialize a variable of type 'CFNumberRef' (aka 'const __CFNumber *') with an rvalue of type 'const void *'
        CFNumberRef spacenum = CFDictionaryGetValue(windict, kCGWindowWorkspace);
                    ^          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
spaceutil.c:21:62: warning: 'kCGWindowWorkspace' is deprecated: first deprecated in macOS 10.8 - No longer supported [-Wdeprecated-declarations]
        CFNumberRef spacenum = CFDictionaryGetValue(windict, kCGWindowWorkspace);
                                                             ^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/System/Library/Frameworks/CoreGraphics.framework/Headers/CGWindow.h:106:30: note: 'kCGWindowWorkspace' has been explicitly marked deprecated here
CG_EXTERN const CFStringRef  kCGWindowWorkspace
                             ^
1 warning and 2 errors generated.
```

My clang++ version is

```
clang++ --version
Apple clang version 13.0.0 (clang-1300.0.29.30)
Target: arm64-apple-darwin20.6.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
```

Any pointers how to fix this error?

error-handling macos-big-sur

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