Hi Yehuda,
C pointers are mapped to the Pointer class. You can create Pointer
objects by yourself, and if you override an Objective-C method with a
C pointer argument, MacRuby will hand you an instance of Pointer.
You code could be rewritten in MacRuby as:
retValuePtr = Pointer.new(:int) # this creates a C pointer of sizeof
(int) of 1 element
retValuePtr[0] = 1 # assigns 1 as the first (and only) element of
the pointer
historyController.repository outputForArguments:['update-ref', '-
mUpdate from GitX', ref.ref, dropCommit.realSha], retValue: retValuePtr
if retValuePtr[0] == 1 # dereference the first element of the pointer
return false
end
# ...
If you are overriding the outputForArguments:retValue: method in
MacRuby, the last argument should be of Pointer type.
def outputForArguments(args, retValue: retValuePtr)
# ...
if some_error
retValuePtr[0] = 1
end
end
It is very easily to crash the program while using a Pointer object
that was created by MacRuby, because MacRuby has no way to know the
boundaries of the original C pointer.
Laurent
On Dec 4, 2009, at 4:16 PM, Yehuda Katz wrote:
I'm currently working with an API that sends me a memory address for
an int and expects me to populate it with a value:
It essentially looks like this:
int retValue = 1;
[historyController.repository outputForArguments:[NSArray
arrayWithObjects:@"update-ref", @"-mUpdate from GitX", [ref ref],
[dropCommit realSha], NULL] retValue:&retValue];
if (retValue) return NO;
I am writing code that implements outputForArguments:retValue:, but
it seems that MacRuby hands me an opaque primitive that I can't use.
When I try to do anything with it, I get EXC_BAD_ACCESS.
Any ideas?
Yehuda Katz
Developer | Engine Yard
(ph) 718.877.1325
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