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find vs find_by vs where
...d are usually replaced with things like this:
Model.all
Model.first
find_by is used as a helper when you're searching for information within a column, and it maps to such with naming conventions. For instance, if you have a column named name in your database, you'd use the following syntax:
Mod...
What should my Objective-C singleton look like? [closed]
... below, I think you should be doing:
+ (id)sharedFoo
{
static dispatch_once_t once;
static MyFoo *sharedFoo;
dispatch_once(&once, ^ { sharedFoo = [[self alloc] init]; });
return sharedFoo;
}
share
...
Docker - how can I copy a file from an image to a host?
...
Actually, I use docker run --rm --entrypoint tar _image_ cC _img_directory_ . | tar xvC _host_directory_
– caligari
Nov 30 '17 at 11:04
add a comment...
Best way to merge two maps and sum the values of same key?
...leads to arguably the shortest/cleanest solution:
scala> import scalaz._
import scalaz._
scala> import Scalaz._
import Scalaz._
scala> val map1 = Map(1 -> 9 , 2 -> 20)
map1: scala.collection.immutable.Map[Int,Int] = Map(1 -> 9, 2 -> 20)
scala> val map2 = Map(1 -> 100, ...
How to disable python warnings
...ee the warning, then it is possible to suppress the warning using the catch_warnings context manager:
import warnings
def fxn():
warnings.warn("deprecated", DeprecationWarning)
with warnings.catch_warnings():
warnings.simplefilter("ignore")
fxn()
I don't condone it, but you could j...
ValueError: setting an array element with a sequence
...9 when building an array of objects (not necessarily lists) that implement __getitem__ as specified here:github.com/numpy/numpy/issues/5100
– dashesy
Nov 21 '14 at 19:13
add a...
How to forward declare a template class in namespace std?
...served for use by the implementation, so you should use something like TEST_H instead of __TEST__. It's not going to generate a warning or an error, but if your program has a clash with an implementation-defined identifier, then it's not guaranteed to compile or run correctly: it's ill-formed. Also ...
Shell脚本编程30分钟入门 - 更多技术 - 清泛网 - 专注C/C++及内核技术
Shell脚本编程30分钟入门linux_shell_30min_guides什么是Shell脚本示例看个例子吧：#! bin shcd ~mkdir shell_tutcd shell_tutfor ((i=0; i<10; i++)); do touch test_$i.txt...
什么是Shell脚本
示例
看个例子吧：
#!/bin/sh
cd ~
mkdir shell_tut
cd shell_tut
for (...
How do synchronized static methods work in Java and can I use it for loading Hibernate entities?
...ic methods, you can
class SomeClass {
private static final Object LOCK_1 = new Object() {};
private static final Object LOCK_2 = new Object() {};
static void foo() {
synchronized(LOCK_1) {...}
}
static void fee() {
synchronized(LOCK_1) {...}
}
static void...
What kind of leaks does automatic reference counting in Objective-C not prevent or minimize?
...chain referring back to an earlier object.
It is for this reason that the __unsafe_unretained and __weak ownership qualifiers exist. The former will not retain any object it points to, but leaves open the possibility of that object going away and it pointing to bad memory, whereas the latter doesn...