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Understanding exactly when a data.table is a reference to (vs a copy of) another data.table
...signing by reference. But you don't use it like you would in base :
DT[3,"foo"] := newvalue # not like this
you use it like this :
DT[3,foo:=newvalue] # like this
That changed DT by reference. Say you add a new column new by reference to the data object, there is no need to do this :
DT...
Custom HTTP headers : naming conventions
... It's a matter of preference and name-spacing; concerns about "X-ClientDataFoo" being supported by any proxy or vendor without the "X" are clearly misplaced.
There's nothing special or magical about the "X-" prefix, but it helps to make it clear that it is a custom header. In fact, RFC-6648 et al h...
Declare a block method parameter without using a typedef
...ally be preferred for more complicated cases.
– Fred Foo
Mar 30 '11 at 13:35
3
- ( void )myMethod...
php发送get、post请求的几种方法 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...file_get_contents函数,以post方式获取url
<?php
$data = array ('foo' => 'bar');
//生成url-encode后的请求字符串，将数组转换为字符串
$data = http_build_query($data);
$opts = array (
<span style="white-space:pre"> </span>'http' => array (
<span style="white-space:pre"...
Type-juggling and (strict) greater/lesser-than comparisons in PHP
...$a <= $b and $b <= $a does not follow $a == $b:
var_dump(NAN <= "foo"); // bool(true)
var_dump("foo" <= NAN); // bool(true)
var_dump(NAN == "foo"); // bool(false)
PHP's <= operator is not transitive, i.e. from $a <= $b and $b <= $c does not follow $a <= $c (Example same as ...
How do servlets work? Instantiation, sessions, shared variables and multithreading
...ect thisIsThreadSafe;
thisIsNOTThreadSafe = request.getParameter("foo"); // BAD!! Shared among all requests!
thisIsThreadSafe = request.getParameter("foo"); // OK, this is thread safe.
}
}
See also:
What is the difference between JSF, Servlet and JSP?
Best option for Sessio...
How to read a (static) file from inside a Python package?
...irectory that itself is added to sys.path. E.g. with sys.path = [..., '.../foo', '.../bar.zip'], eggs go in .../foo, but packages in bar.zip can also be imported. You cant use pkg_resources to extract data from packages in bar.zip. I haven't checked if setuptools registers the necessary loader for i...
public friend swap member function
...unding namespace. For example, these were equivalent pre-standard:
struct foo
{
friend void bar()
{
// baz
}
};
// turned into, pre-standard:
struct foo
{
friend void bar();
};
void bar()
{
// baz
}
However, when ADL was invented this was removed. The friend fun...
Undo scaffolding in Rails
...db:rollback
You can create scaffolding using:
rails generate scaffold MyFoo
(or similar), and you can destroy/undo it using
rails destroy scaffold MyFoo
That will delete all the files created by generate, but not any additional changes you may have made manually.
...
Multiprocessing - Pipe vs Queue
...]) exited while multiprocessing
Traceback (most recent call last):
File "foo.py", line 19, in __init__
self.run(args)
File "foo.py", line 46, in run
KeyError: 'that'
Source Code:
"""
multi_pipe.py
"""
from multiprocessing import Process, Pipe
import time
def reader_proc(pipe):
...