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Specifying column name in a “references” migration
...want to check out the guide I link for more info on migrations in general, and you may even end up putting calling SQL code directly in your migration. I would say ignore it, as it isn't a normal part of rails, you will get 0 performance out of it, as rails' default generated SQL queries take no adv...
Comparing boxed Long values 127 and 128
...s this:
true
false
For the 127L value, since both references (val1 and val2) point to the same object instance in memory (cached), it returns true.
On the other hand, for the 128 value, since there is no instance for it cached in memory, a new one is created for any new assignments for boxe...
Get last element of Stream/List in a one-liner
...ch element will be returned.
The implementation works for both sequential and parallel streams. That might be surprising at first glance, and unfortunately the documentation doesn't state it explicitly. However, it is an important feature of streams, and I try to clarify it:
The Javadoc for the m...
How do I undo a checkout in git?
...to/file
For the entire repository working copy:
git reset --hard HEAD
And if that doesn't work, then you can look in the reflog to find your old head SHA and reset to that:
git reflog
git reset --hard <sha from reflog>
HEAD is a name that always points to the latest commit in your curr...
Python dict how to create key or append an element to key?
...his answer suggests a far better way. In fact it gets set() as an argument and allows you to use add() method...
– fatih_dur
Feb 9 '16 at 2:27
...
Calculating how many minutes there are between two times
I have a datagridview in my application which holds start and finish times. I want to calculate the number of minutes between these two times. So far I have got:
...
How do I create a Python function with optional arguments?
... *args, **kwargs):
for ar in args:
print ar
myfunc(a,b,c,d,e,f)
And it will print values of c,d,e,f
Similarly you could use the kwargs argument and then you could name your parameters.
def myfunc(a,b, *args, **kwargs):
c = kwargs.get('c', None)
d = kwargs.get('d', None)
...
Difference between await and ContinueWith
Can someone explain if await and ContinueWith are synonymous or not in the following example. I'm trying to use TPL for the first time and have been reading all the documentation, but don't understand the difference.
...
Sort rows in data.table in decreasing order on string key `order(-x,v)` gives error on data.table 1.
...
Update
data.table v1.9.6+ now supports OP's original attempt and the following answer is no longer necessary.
You can use DT[order(-rank(x), y)].
x y v
1: c 1 7
2: c 3 8
3: c 6 9
4: b 1 1
5: b 3 2
6: b 6 3
7: a 1 4
8: a 3 5
9: a 6 6
...
PHP cURL vs file_get_contents
...ests where the header, HTTP request method, timeout, cookiejar, redirects, and other important things do not matter.
fopen() with a stream context or cURL with setopt are powerdrills with every bit and option you can think of.
...