大约有 15,000 项符合查询结果（耗时：0.0376秒） [XML]
nonlocal keyword in Python 2.x
...local variable but it seems like this keyword is not available in python 2.x. How should one access nonlocal variables in closures in these versions of python?
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How to check if a number is a power of 2
...
There's a simple trick for this problem:
bool IsPowerOfTwo(ulong x)
{
return (x & (x - 1)) == 0;
}
Note, this function will report true for 0, which is not a power of 2. If you want to exclude that, here's how:
bool IsPowerOfTwo(ulong x)
{
return (x != 0) && ((x &...
Why aren't python nested functions called closures?
... access to a local variable from an enclosing scope that has finished its execution.
def make_printer(msg):
def printer():
print msg
return printer
printer = make_printer('Foo!')
printer()
When make_printer is called, a new frame is put on the stack with the compiled code for the...
jQuery deferreds and promises - .then() vs .done()
... information on pipe().
success() and error() are only available on the jqXHR object returned by a call to ajax(). They are simple aliases for done() and fail() respectively:
jqXHR.done === jqXHR.success
jqXHR.fail === jqXHR.error
Also, done() is not limited to a single callback and will filter ...
Remove empty strings from a list of strings
...ythonic way:
>>> strings = ["first", "", "second"]
>>> [x for x in strings if x]
['first', 'second']
If the list must be modified in-place, because there are other references which must see the updated data, then use a slice assignment:
strings[:] = [x for x in strings if x]
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What is 'Currying'?
...o curried functions in several articles and blogs but I can't find a good explanation (or at least one that makes sense!)
1...
In R, how to get an object's name after it is sent to a function?
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The old deparse-substitute trick:
a<-data.frame(x=1:10,y=1:10)
test<-function(z){
mean.x<-mean(z$x)
nm <-deparse(substitute(z))
print(nm)
return(mean.x)}
test(a)
#[1] "a" ... this is the side-effect of the print() call
# ... you could have...
How do I put two increment statements in a C++ 'for' loop?
... operator at all. I checked that in GCC as follows:
int i=0;
int a=5;
int x=0;
for(i; i<5; x=i++,a++){
printf("i=%d a=%d x=%d\n",i,a,x);
}
I was expecting x to pick up the original value of a, so it should have displayed 5,6,7.. for x. What I got was this
i=0 a=5 x=0
i=1 a=6 x=0
i=2 a=7 ...
Elegant way to combine multiple collections of elements?
...rary number of collections, each containing objects of the same type (for example, List<int> foo and List<int> bar ). If these collections were themselves in a collection (e.g., of type List<List<int>> , I could use SelectMany to combine them all into one collection.
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How to determine if a point is in a 2D triangle? [closed]
...ou started:
float sign (fPoint p1, fPoint p2, fPoint p3)
{
return (p1.x - p3.x) * (p2.y - p3.y) - (p2.x - p3.x) * (p1.y - p3.y);
}
bool PointInTriangle (fPoint pt, fPoint v1, fPoint v2, fPoint v3)
{
float d1, d2, d3;
bool has_neg, has_pos;
d1 = sign(pt, v1, v2);
d2 = sign(pt, ...