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Setting the selected value on a Django forms.ChoiceField
...rying to assign the selected value to a ChoiceField.
If you have already called super().__init__ in your Form class, you should update the form.initial dictionary, not the field.initial property. If you study form.initial (e.g. print self.initial after the call to super().__init__), it will contai...
FAT32系统中长文件名的存储 - C/C++ - 清泛网 - 专注C/C++及内核技术
...)。
(4)、如果存在老OS或程序无法读取的字符，换以"_"
短文件格式的目录项。其参数意义见表14：
表14 FAT32短文件目录项32个字节的表示定义
字节偏移(16进制)
字节数
定义
0x0~0x7
8
文件名
0x8~0xA...
How to limit the amount of concurrent async I/O operations?
... Stephen Toub, but the less announced news is that the async semaphore actually made it into the Beta release of .NET 4.5
If you look at our beloved SemaphoreSlim class (which you should be using since it's more performant than the original Semaphore), it now boasts the WaitAsync(...) series of ove...
jQuery AJAX file upload PHP
...ript to look like this:
$('#upload').on('click', function() {
var file_data = $('#sortpicture').prop('files')[0];
var form_data = new FormData();
form_data.append('file', file_data);
alert(form_data);
$.ajax({
url: 'uploa...
How do I append text to a file?
...ther source.
Or else entered at the keyboard, doesn't matter.
^D
Essentially, you can dump any text you want into the file. CTRL-D sends an end-of-file signal, which terminates input and returns you to the shell.
share
...
How to refer to relative paths of resources when working with a code repository
...Try to use a filename relative to the current files path. Example for './my_file':
fn = os.path.join(os.path.dirname(__file__), 'my_file')
In Python 3.4+ you can also use pathlib:
fn = pathlib.Path(__file__).parent / 'my_file'
...
What is the function __construct used for?
I have been noticing __construct a lot with classes. I did a little reading and surfing the web, but I couldn't find an explanation I could understand. I am just beginning with OOP.
...
C++虚析构函数解析 - C/C++ - 清泛网 - 专注C/C++及内核技术
...类的状况发生。
以下内容转自： http://blog.sina.com.cn/s/blog_7c773cc50100y9hz.html
a.第一段代码
#include<iostream>
using namespace std;
class ClxBase{
public:
ClxBase() {};
~ClxBase() {cout << "Output from the destructor of class ClxBase!" << endl;};
void ...
Proper way to use **kwargs in Python
...*kwargs):
...etc...
this is not true. In the latter case, f can be called as f(23, 42), while the former case accepts named arguments only -- no positional calls. Often you want to allow the caller maximum flexibility and therefore the second form, as most answers assert, is preferable: but ...
How to delete an object by id with entity framework
...
The same as @Nix with a small change to be strongly typed:
If you don't want to query for it just create an entity, and then delete it.
Customer customer = new Customer () { Id = id };
context.Customers.Attach(custome...