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What is the purpose of the single underscore “_” variable in Python?
...cate that part
of a function result is being deliberately ignored (Conceptually, it is being discarded.), as in code like:
label, has_label, _ = text.partition(':').
As part of a function definition (using either def or lambda), where
the signature is fixed (e.g. by a callback or parent class API), ...
PHP Fatal error: Cannot redeclare class
...
It means you've already created a class.
For instance:
class Foo {}
// some code here
class Foo {}
That second Foo would throw the error.
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Android Fatal signal 11 (SIGSEGV) at 0x636f7d89 (code=1). How can it be tracked down?
...e NDK documents. Ever since the release NDK-r6, it has provided a utility called ndk-stack.
Following is the content from official NDK documents with the NDK-r9 tar ball.
Overview:
ndk-stack is a simple tool that allows you to filter stack traces as they appear in the output of 'adb logcat' and r...
find: missing argument to -exec
...
A -exec command must be terminated with a ; (so you usually need to type \; or ';' to avoid interpretion by the shell) or a +. The difference is that with ;, the command is called once per file, with +, it is called just as few times as possible (usually once, but there is a maxi...
What is attr_accessor in Ruby?
...d. What it does is create more methods for you.
So this code here:
class Foo
attr_accessor :bar
end
is equivalent to this code:
class Foo
def bar
@bar
end
def bar=( new_value )
@bar = new_value
end
end
You can write this sort of method yourself in Ruby:
class Module
def v...
C++ catching all exceptions
...
try{
// ...
} catch (...) {
// ...
}
will catch all C++ exceptions, but it should be considered bad design. You can use c++11's new current_exception mechanism, but if you don't have the ability to use c++11 (legacy code systems requiring a rewrite), then you have no name...
How do you rename a MongoDB database?
... changes to every shard if the DB is sharded, plus the config servers have all the shard metadata in terms of namespaces with their full names.
There would be absolutely no way to do this on a live system.
To do it offline, it would require re-writing every single database file to accommod...
Automatically capture output of last command into a variable using Bash?
...
This is a really hacky solution, but it seems to mostly work some of the time. During testing, I noted it sometimes didn't work very well when getting a ^C on the command line, though I did tweak it a bit to behave a bit better.
This...
JavaScript hashmap equivalent
...
Hash your objects yourself manually, and use the resulting strings as keys for a regular JavaScript dictionary. After all, you are in the best position to know what makes your objects unique. That's what I do.
Example:
var key = function(obj){
// Some un...
How to check that an element is in a std::set?
... Note that using count() instead of find() is never better but potentially worse. This is because find() will return after the first match, count() will always iterate over all elements.
– Frerich Raabe
Nov 9 '09 at 15:50
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