大约有 40,000 项符合查询结果（耗时：0.0395秒） [XML]
How should one use std::optional?
...std::string s, int& i);
Another way that this could be done is especially bad:
int* try_parse_int(std::string s); //return nullptr if fail
This requires dynamic memory allocation, worrying about ownership, etc. - always prefer one of the other two signatures above.
Another example:
clas...
Convert a char to upper case using regular expressions (EditPad Pro)
...m using EditPad Pro (however I am willing to use any other tool that would allow me to do this, as long as it is free to try, since I only need to do this once).
...
Declaring an enum within a class
...uct Color
{
enum Type
{
Red, Green, Black
};
Type t_;
Color(Type t) : t_(t) {}
operator Type () const {return t_;}
private:
//prevent automatic conversion for any other built-in types such as bool, int, etc
template<typename T>
operator T () const;
};
...
How to find the size of localStorage
...ly developing a site that will make use of HTML5's localStorage. I've read all about the size limitations for different browsers. However, I haven't seen anything on how to find out the current size of a localStorage instance. This question seems to indicate that JavaScript doesn't have a built in...
How to pip or easy_install tkinter on Windows
...
Well I can see two solutions here:
1) Follow the Docs-Tkinter install for Python (for Windows):
Tkinter (and, since Python 3.1, ttk) are included with all standard Python distributions. It is important that you use a version of Python supporting Tk 8.5 or greater, and ttk. We recommend in...
What is the difference (if any) between Html.Partial(view, model) and Html.RenderPartial(view,model)
...
The usage of the two methods is slightly different:
@Html.Partial("_yourPartialView")
@{ Html.RenderPartial("_yourPartialView "); }
The choice of which to use depends on your requirements. If you need
to further manipulate the string being injected in the response
stream, you shoul...
How to check Oracle database for long running queries
...ime -- Time since current mode was granted
from
v$locked_object, all_objects, v$lock
where
v$locked_object.object_id = all_objects.object_id AND
v$lock.id1 = all_objects.object_id AND
v$lock.sid = v$locked_object.session_id
order by
session_id, ctime desc, object_name
/
This is a...
Number of processors/cores in command line
...
Make sure to nproc --all for all installed Processing Units. Without --all, nproc only shows Processing Units available to the current process. Read the man page for more details. MMV.
– JamesThomasMoon1979
...
Can anonymous class implement interface?
... properties. No other kinds of class members such as methods or events are allowed. An anonymous type cannot be cast to any interface or type except for object.
share
|
improve this answer
...
Correct way to use get_or_create?
...f the fields have to be included in defaults. In case CREATE event occurs, all the fields are taken into consideration.
It looks like you need to be returning into a tuple, instead of a single variable, do like this:
customer.source,created = Source.objects.get_or_create(name="Website")
...