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What is a memory fence?
...ead/writes occur in the order you expect. For example a 'full fence' means all read/writes before the fence are comitted before those after the fence.
Note memory fences are a hardware concept. In higher level languages we are used to dealing with mutexes and semaphores - these may well be implemen...
remove None value from a list without removing the 0 value
... - it's just for scientific purposes)
>>> from operator import is_not
>>> from functools import partial
>>> L = [0, 23, 234, 89, None, 0, 35, 9]
>>> filter(partial(is_not, None), L)
[0, 23, 234, 89, 0, 35, 9]
...
Adding :default => true to boolean in existing Rails column
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change_column is a method of ActiveRecord::Migration, so you can't call it like that in the console.
If you want to add a default value for this column, create a new migration:
rails g migration add_default_value_to_show_attribute
Then in the migration created:
# That's the more generic way t...
How to reload a clojure file in REPL
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:reload-all should also work. The OP specifically says it doesn't, but I think there was something else wrong in the OP's dev environment because for a single file the two (:reload and :reload-all) should have the same effect. Here'...
error LNK2019: 无法解析的外部符号_socket，该符号在函数 中被引用 - C/C+...
error LNK2019: 无法解析的外部符号_socket，该符号在函数 中被引用1>NetClient.obj : error LNK2019: 无法解析的外部符号 _closesocket@4，该符号在函数 _main 中被引用1>NetClient.obj : error L...1>NetClient.obj : error LNK2019: 无法解析的外部符号 _closesocket@...
Build Eclipse Java Project from Command Line
...ore.aptBuild
It uses the jdt apt plugin to build your workspace automatically. This is also known as a 'Headless Build'. Damn hard to figure out. If you're not using a win32 exe, you can try this:
java -cp startup.jar -noSplash -data "D:\Source\MyProject\workspace" -application org.eclipse.jdt....
How is the undo tree used in Vim?
...
See also :h undo-redo, which lists all the commands and their usage.
There are two ways to traverse the undo tree. One is to go "back in time". g+ and g- will traverse all of the nodes in the tree in chronological or reverse-chronological order (which can...
How to deep copy a list?
... don't make a deep copy using list() (Both list(...) and testList[:] are shallow copies).
You use copy.deepcopy(...) for deep copying a list.
deepcopy(x, memo=None, _nil=[])
Deep copy operation on arbitrary Python objects.
See the following snippet -
>>> a = [[1, 2, 3], [4, 5, 6]]...
#ifdef replacement in the Swift language
... After i set the custom flag -DLOCAL, on my #if LOCAl #else #endif, it falls into the #else section. I duplicated the original target AppTarget and rename it to AppTargetLocal & set its custom flag.
– Perwyl Liu
Jul 20 '16 at 6:48
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Link to reload current page
...ouldn't rely entirely on my original answer, but rather try both the empty string and the period in different browsers for your specific use and make sure you get the desired behaviour.
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