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performSelector may cause a leak because its selector is unknown
...
Solution
The compiler is warning about this for a reason. It's very rare that this warning should simply be ignored, and it's easy to work around. Here's how:
if (!_controller) { return; }
SEL selector = NSSelectorFromString(@"someMethod");
IMP imp = [_controller meth...
Detecting endianness programmatically in a C++ program
...t will often be warned against by compiler. That's exactly what unions are for !
bool is_big_endian(void)
{
union {
uint32_t i;
char c[4];
} bint = {0x01020304};
return bint.c[0] == 1;
}
The principle is equivalent to the type case as suggested by others, but this is...
How can I rename a field for all documents in MongoDB?
...}. You need the multi:true to update all your records.
Or you can use the former way:
remap = function (x) {
if (x.additional){
db.foo.update({_id:x._id}, {$set:{"name.last":x.name.additional}, $unset:{"name.additional":1}});
}
}
db.foo.find().forEach(remap);
In MongoDB 3.2 you can also...
Find current directory and file's directory [duplicate]
...g directory use
import os
cwd = os.getcwd()
Documentation references for the modules, constants and functions used above:
The os and os.path modules.
The __file__ constant
os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountere...
Escaping regex string
I want to use input from a user as a regex pattern for a search over some text. It works, but how I can handle cases where user puts characters that have meaning in regex?
...
How to obtain the number of CPUs/cores in Linux from the command line?
...will count the number of lines starting with "processor" in /proc/cpuinfo
For systems with hyper-threading, you can use
grep ^cpu\\scores /proc/cpuinfo | uniq | awk '{print $4}'
which should return (for example) 8 (whereas the command above would return 16)
...
Cleaner way to update nested structures
...sal and 'mutation' of an immutable data structure. Scalaz provides Zippers for Stream (scalaz.Zipper), and Tree (scalaz.TreeLoc). It turns out that the structure of the zipper is automatically derivable from the original data structure, in a manner that resembles symbolic differentiation of an algeb...
How to get last items of a list in Python?
...
You can use negative integers with the slicing operator for that. Here's an example using the python CLI interpreter:
>>> a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
>>> a
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
>>> a[-9:]
[4, 5, 6, 7, 8, 9, 10, 11, 12]...
How do I pass a method as a parameter in Python
...t a little bit more complicated. method2 has to be written with a bit of information about how to pass arguments to method1, and it needs to get values for those arguments from somewhere. For instance, if method1 is supposed to take one argument:
def method1(self, spam):
return 'hello ' + str(sp...
How do I pass parameters into a PHP script through a webpage?
...s set, but empty if there are no GET parameters set. empty() returns false for empty strings and arrays.
– Tim S.
Mar 7 '13 at 8:15
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