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What's wrong with overridable method calls in constructors?
...tion performed by the subclass constructor, the method will not behave as expected.
Here's an example to illustrate:
public class ConstructorCallsOverride {
public static void main(String[] args) {
abstract class Base {
Base() {
overrideMe();
}...
C语言结构体里的成员数组和指针 - C/C++ - 清泛网 - 专注C/C++及内核技术
...你把14行的printf语句改成：
1
printf("%x\n", f.a->s);
你会看到程序不crash了。程序输出：4。 这下你知道了，访问0x4的内存地址，不crash才怪。于是，你一定会有如下的问题：
1）为什么不是 13行if语...
Why is “if not someobj:” better than “if someobj == None:” in Python?
I've seen several examples of code like this:
9 Answers
9
...
How can you find the height of text on an HTML canvas?
The spec has a context.measureText(text) function that will tell you how much width it would require to print that text, but I can't find a way to find out how tall it is. I know it's based on the font, but I don't know to convert a font string to a text height.
...
Do I need to convert .CER to .CRT for Apache SSL certificates? If so, how?
...
File extensions for cryptographic certificates aren't really as standardized as you'd expect. Windows by default treats double-clicking a .crt file as a request to import the certificate into the Windows Root Certificate store, but...
Apache is downloading php files instead of displaying them
...
The correct AddType for php is application/x-httpd-php
AddType application/x-httpd-php .php
AddType application/x-httpd-php-source .phps
Also make sure your php module is loaded
LoadModule php5_module modules/mod_php55.so
When you're configurin...
How to generate keyboard events in Python?
...rue)
INPUT_MOUSE = 0
INPUT_KEYBOARD = 1
INPUT_HARDWARE = 2
KEYEVENTF_EXTENDEDKEY = 0x0001
KEYEVENTF_KEYUP = 0x0002
KEYEVENTF_UNICODE = 0x0004
KEYEVENTF_SCANCODE = 0x0008
MAPVK_VK_TO_VSC = 0
# msdn.microsoft.com/en-us/library/dd375731
VK_TAB = 0x09
VK_MENU = 0x12
# C struct defi...
Multiple levels of 'collection.defaultdict' in Python
...will call the lambda which will create a new defaultdict(int). And when d[existing_key][new_key2] is accessed, a new int will be created.
– interjay
Oct 11 '13 at 12:53
11
...
Best practice for Python assert
...
To be able to automatically throw an error when x become less than zero throughout the function. You can use class descriptors. Here is an example:
class LessThanZeroException(Exception):
pass
class variable(object):
def __init__(self, value=0):
self.__x ...
What differences, if any, between C++03 and C++11 can be detected at run-time?
...emplate<int> struct int_ { };
template<typename T> bool isCpp0xImpl(int_<T::X>*) { return true; }
template<typename T> bool isCpp0xImpl(...) { return false; }
enum A { X };
bool isCpp0x() {
return isCpp0xImpl<A>(0);
}
You can also abuse the new keywords
struct a ...