大约有 22,000 项符合查询结果（耗时：0.0423秒） [XML]
belongs_to through associations
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# ------- Helpers -------
def question
answer.question
end
# extra sugar
def question_id
answer.question_id
end
end
This approach is pretty simple, but comes with tradeoffs. It requires Rails to load answer from the db, and then question. This can be optimized later by eage...
const vs constexpr on variables
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Are you sure? Because const int N = 10; char a[N]; works, and array bounds must be compile-time constants.
– fredoverflow
Nov 12 '12 at 16:22
10
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How to make a smaller RatingBar?
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you can remove some extra padding by specifying height of rating bar ex : android:layout_height="40dp"
– Manohar Reddy
Aug 28 '17 at 13:43
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How do I 'svn add' all unversioned files to SVN?
... awk? Awk can do pattern matching: awk '/^[?]/{print $2}'; No need for the extra grep process.
– bdrx
Feb 26 '15 at 13:59
1
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What is the meaning of “POSIX”?
...cannot be used
. is cwd, .. parent
portable filenames
use at most max 14 chars and 256 for the full path
can only contain: a-zA-Z0-9._-
See also: what is posix compliance for filesystem?
Command line utility API conventions
Not mandatory, used by POSIX, but almost nowhere else, notably not in ...
Add a default value to a column through a migration
..., since change_column is irreversible.
Instead, though it may be a couple extra lines, you should use def up and def down
So if you have a column with no default value, then you should do this to add a default value.
def up
change_column :users, :admin, :boolean, default: false
end
def down
...
Generate random numbers using C++11 random library
...;
}
};
thread_local backoff_time_t backoff_time;
int main(int argc, char** argv) {
double x1 = backoff_time.rand();
double x2 = backoff_time.rand();
double x3 = backoff_time.rand();
double x4 = backoff_time.rand();
return 0;
}
~
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How can I add a column that doesn't allow nulls in a Postgresql database?
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Or, create a new table as temp with the extra column, copy the data to this new table while manipulating it as necessary to fill the non-nullable new column, and then swap the table via a two-step name change.
Yes, it is more complicated, but you may need to do it...
ZMQ: 基本原理 - 开源 & Github - 清泛网移动版 - 专注C/C++及内核技术
...q_connect (s, "tcp://192.168.0.111:5555");
/* Message routing */
const char data [] = "ABC";
zmq_send (s, data, sizeof (data), 0);
区分拓扑建立和消息路由严格地说不是不可缺少的。毕竟，混合这两个为一个单独的函数是很容易的：
zmq_send (s, "tcp://19...
input type=“text” vs input type=“search” in HTML5
...x in iTunes or some other app). Currently, it's there so that YOU can add extra functionality/presentation by knowing it's a search box.
– Norguard
Jul 21 '12 at 15:07
40
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