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How do I avoid capturing self in blocks when implementing an API?
... If you're not using Automatic Reference Counting (ARC), you can do this:
__block MyDataProcessor *dp = self;
self.progressBlock = ^(CGFloat percentComplete) {
[dp.delegate myAPI:dp isProcessingWithProgress:percentComplete];
}
The __block keyword marks variables that can be modified inside th...
How to import a module given its name as string?
...hat's pretty much how you do it.
For newer versions, see importlib.import_module for Python 2 and and Python 3.
You can use exec if you want to as well.
Or using __import__ you can import a list of modules by doing this:
>>> moduleNames = ['sys', 'os', 're', 'unittest']
>>> m...
Dynamically set local variable [duplicate]
... out in the comments there are exceptions, for example classes that define __slots__). Function locals can be optimised for speed because the compiler (usually) knows all the names in advance, so there isn't a dictionary until you call locals().
In the C implementation of Python locals() (called fr...
super() raises “TypeError: must be type, not classobj” for new-style class
...: pass
>>> instance = OldStyle()
>>> issubclass(instance.__class__, object)
False
and not (as in the question):
>>> isinstance(instance, object)
True
For classes, the correct "is this a new-style class" test is:
>>> issubclass(OldStyle, object) # OldStyle i...
Is gcc's __attribute__((packed)) / #pragma pack unsafe?
...
Yes, __attribute__((packed)) is potentially unsafe on some systems. The symptom probably won't show up on an x86, which just makes the problem more insidious; testing on x86 systems won't reveal the problem. (On the x86, misalig...
Python __call__ special method practical example
I know that __call__ method in a class is triggered when the instance of a class is called. However, I have no idea when I can use this special method, because one can simply create a new method and perform the same operation done in __call__ method and instead of calling the instance, you can c...
How to find out what type of a Mat object is with Mat::type() in OpenCV
...st.
string type2str(int type) {
string r;
uchar depth = type & CV_MAT_DEPTH_MASK;
uchar chans = 1 + (type >> CV_CN_SHIFT);
switch ( depth ) {
case CV_8U: r = "8U"; break;
case CV_8S: r = "8S"; break;
case CV_16U: r = "16U"; break;
case CV_16S: r = "16S"; break;...
Which rows are returned when using LIMIT with OFFSET in MySQL?
...data between the two digits but now its clear :)
– MR_AMDEV
Sep 16 '18 at 15:09
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BSS段、数据段、代码段、堆与栈 剖析 - C/C++ - 清泛网 - 专注C/C++及内核技术
...下其各自的.asm，发现在程序1.asm 中ar 的定义如下：
_BSS SEGMENT
?ar@@3PAHA DD 0493e0H DUP (?) ; ar
_BSS ENDS
而在程序2.asm 中，ar 被定义为：
_DATASEGMENT
?ar@@3PAHA DD 01H ; ar
DD 02H
DD 03H
ORG $+1199988
_DATAENDS
区别很明显，一个位于.bss 段...
How do I flag a method as deprecated in Objective-C 2.0?
...x is provided to mark methods as deprecated:
@interface SomeClass
-method __attribute__((deprecated));
@end
or:
#include <AvailabilityMacros.h>
@interface SomeClass
-method DEPRECATED_ATTRIBUTE; // or some other deployment-target-specific macro
@end
...