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Cannot use ref or out parameter in lambda expressions
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@Qwertie I got this to work with full parameterization, meaning, include the types on a, b, c, and d and it works. See BenAdams answer (though he misunderstands the original question, too).
– Ed Bayiates
Feb 10 '16 at 19:02
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mongodb count num of distinct values per field/key
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},
{ $unwind: "$keywords" },
{
$group: {
_id: {$toLower: '$keywords'},
count: { $sum: 1 }
}
},
{
$match: {
count: { $gte: 2 }
}
},
{ $sort : { count : -1} },
{ $limit : 100 }
]);
that give result s...
What's the point of malloc(0)?
...gree. If malloc(0) returned a valid pointer, then malloc() returning NULL means "failure" always, and 0 isn't a special case anymore, which is more consistent.
– Alok Singhal
Jan 7 '10 at 17:57
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廉价共享存储解决方案2-drbd+cman+gfs2 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...lic/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
a9:8a:3a:3d:64:eb:0b:de:94:a5:92:e4:ba:5d:f3:de root@gfs_1
The key's rand...
Conditional Variable vs Semaphore
...s can be used to implement exclusive access to variables, however they are meant to be used for synchronization. Mutexes, on the other hand, have a semantics which is strictly related to mutual exclusion: only the process which locked the resource is allowed to unlock it.
Unfortunately you cannot i...
Difference between dispatch_async and dispatch_sync on serial queue?
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I do mean serial execution. In point of view that all tasks are executed serial regards to other tasks in the same queue. Of cause it still can be concurrent regards to other queues. It is the whole point of GCD that tasks can be ...
搭建高可用mongodb集群（二）—— 副本集 - 大数据 & AI - 清泛网 - 专注C/...
...admin数据库
use admin
#定义副本集配置变量，这里的 _id:”repset” 和上面命令参数“ –replSet repset” 要保持一样。
config = { _id:"repset", members:[
{_id:0,host:"192.168.1.136:27017"},
{_id:1,host:"192.168.1.137:27017"},
{_id:2,host:...
What do “branch”, “tag” and “trunk” mean in Subversion repositories?
...t not make any changes. Of course, a tag being just part of the repository means the full history is available. If someone changes a tag, you can track that and why. In many VCS, if you modify a tag, there may not be any way to know.
– David W.
Mar 1 '15 at 19:...
boost多索引容器multi_index_container实战 - C/C++ - 清泛网 - 专注C/C++及内核技术
...自boost文档
template<typename Tag,typename MultiIndexContainer>
void print_out_by( const MultiIndexContainer& s )
{
/* obtain a reference to the index tagged by Tag */
const typename boost::multi_index::index<MultiIndexContainer,Tag>::type& i = get<Tag>(s);
t...
Is it abusive to use IDisposable and “using” as a means for getting “scoped behavior” for exception
...
I don't think so, necessarily. IDisposable technically is meant to be used for things that have non-managed resources, but then the using directive is just a neat way of implementing a common pattern of try .. finally { dispose }.
A purist would argue 'yes - it's abusive', and in t...