大约有 44,000 项符合查询结果（耗时：0.1756秒） [XML]
std::unique_lock or std::lock_guard?
...
The difference is that you can lock and unlock a std::unique_lock. std::lock_guard will be locked only once on construction and unlocked on destruction.
So for use case B you definitely need a std::unique_lock for the condition variable. In case A it depends ...
Removing transforms in SVG files
I have been struggling with this for a while, and can't seem to find an answer (that works) anywhere. I have an SVG file which looks like this:
...
Looping through localStorage in HTML5 and JavaScript
...ock, just looking at, it should work. Is there a reason I should use parse and not eval? I'm using eval now to get it from a string, but is parse better/faster?
– Oscar Godson
Jun 29 '10 at 21:15
...
How do I convert seconds to hours, minutes and seconds?
...his is the best way, IMHO, as you can then use arithmetic on the timedelta and any datetime objects.
– Matthew Schinckel
Apr 22 '09 at 3:13
13
...
What is lexical scope?
...
I understand them through examples. :)
First, lexical scope (also called static scope), in C-like syntax:
void fun()
{
int x = 5;
void fun2()
{
printf("%d", x);
}
}
Every inner level can access its outer l...
How to retry after exception?
...
Do a while True inside your for loop, put your try code inside, and break from that while loop only when your code succeeds.
for i in range(0,100):
while True:
try:
# do stuff
except SomeSpecificException:
continue
break
...
Regex not operator
... In the edit of your question you put the {4} outside the lookahead and in this comment you put it inside: which one did you try? Also: if you want (20019) to match, then you must add the \) inside your lookahead: \((?![\d]{4}\))[0-9a-zA-z _\.\-:]+\)
– Joachim Sauer
...
How to set a Django model field's default value to a function call / callable (e.g., a date relative
...e class.
PRE Django 1.7
Django lets you pass a callable as the default, and it will invoke it each time, just as you want:
from datetime import datetime, timedelta
class MyModel(models.Model):
# default to 1 day from now
my_date = models.DateTimeField(default=lambda: datetime.now() + timedel...
Rails: fields_for with index?
...uestion do |fq| %>
# here you have both the 'question' object and the current 'index'
<% end %>
<% end %>
From:
http://railsapi.com/doc/rails-v3.0.4/classes/ActionView/Helpers/FormHelper.html#M006456
It’s also possible to specify the
instance to be used:
<%= fo...
How to debug JavaScript / jQuery event bindings with Firebug or similar tools?
...need to debug a web application that uses jQuery to do some fairly complex and messy DOM manipulation. At one point, some of the events that were bound to particular elements, are not fired and simply stop working.
...