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What does the Q_OBJECT macro do? Why do all Qt objects need this macro?
...ing Qt and noticed that all the example class definitions have the macro Q_OBJECT as the first line. What is the purpose of this preprocessor macro?
...
What is the difference between Python's list methods append and extend?
...ppend
The list.append method appends an object to the end of the list.
my_list.append(object)
Whatever the object is, whether a number, a string, another list, or something else, it gets added onto the end of my_list as a single entry on the list.
>>> my_list
['foo', 'bar']
>>&...
Why rename synthesized properties in iOS with leading underscores? [duplicate]
...ariables had to be instantiated explicitly:
@interface Foo : Bar {
Baz *_qux;
}
@property (retain) Baz *qux;
@end
@implementation Foo
@synthesize qux = _qux;
- (void)dealloc {
[_qux release];
[super dealloc];
}
@end
People would prefix their instance variables to differentiate them from...
What does #defining WIN32_LEAN_AND_MEAN exclude exactly?
I found the explanation defining WIN32_LEAN_AND_MEAN "reduces the size of the Win32 header files by excluding some of the less frequently used APIs". Somewhere else I read that it speeds up the build process.
...
Placeholder in UITextView
...uble.
UIPlaceHolderTextView.h:
#import <Foundation/Foundation.h>
IB_DESIGNABLE
@interface UIPlaceHolderTextView : UITextView
@property (nonatomic, retain) IBInspectable NSString *placeholder;
@property (nonatomic, retain) IBInspectable UIColor *placeholderColor;
-(void)textChanged:(NSNotif...
How can I convert JSON to CSV?
...this:
{
"pk": 22,
"model": "auth.permission",
"codename": "add_logentry",
"content_type": 8,
"name": "Can add log entry"
},
......]
Here is my code to generate CSV from that:
import csv
import json
x = """[
{
"pk": 22,
"model": "auth.permission",
...
Assignment inside lambda expression in Python
...asons. For example, we will be able to write the following:
import sys
say_hello = lambda: (
message := "Hello world",
sys.stdout.write(message + "\n")
)[-1]
say_hello()
In Python 2, it was possible to perform local assignments as a side effect of list comprehensions.
import sys
say_hell...
Chrome sendrequest error: TypeError: Converting circular structure to JSON
...mit": null,
"size": 0,
"chunks": [],
"writable": true,
"readable": false,
"_events": {
"pipe": [null, null],
"error": [null]
},
"before": [null],
"after": [],
"response": {
"output": [],
"outputEncodings": [],
"writable": true,
"_last": false,
"chunkedEncoding": false,
...
How can I print the contents of a hash in Perl?
...
Easy:
print "$_ $h{$_}\n" for (keys %h);
Elegant, but actually 30% slower (!):
while (my ($k,$v)=each %h){print "$k $v\n"}
share
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im...
Cannot open include file 'afxres.h' in VC2010 Express
...nks, then i get the error: error RC2104: undefined keyword or key name: IDC_STATIC
– clamp
Aug 25 '10 at 13:16
@clamp:...