大约有 40,000 项符合查询结果（耗时：0.0478秒） [XML]
Update MongoDB field using value of another field
...
The best way to do this is in version 4.2+ which allows using of aggregation pipeline in the update document and the updateOne, updateMany or update collection method. Note that the latter has been deprecated in most if not all languages drivers.
MongoDB 4.2+
Version 4.2 ...
Why does running the Flask dev server run itself twice?
...g is the library that supplies Flask with the development server when you call app.run().
See the restart_with_reloader() function code; your script is run again with subprocess.call().
If you set use_reloader to False you'll see the behaviour go away, but then you also lose the reloading function...
Why does GCC generate such radically different assembly for nearly the same C code?
...e(). I'll spare you the assembly, but it is identical - register names and all.
Step 2: Mathematical reduction: x + (y ^ x) = y
sign can only take one of two values, 0 or 0x80000000.
When x = 0, then x + (y ^ x) = y then trivial holds.
Adding and xoring by 0x80000000 is the same. It flips the sign...
Python ElementTree module: How to ignore the namespace of XML files to locate matching element when
I want to use the method of "findall" to locate some elements of the source xml file in the ElementTree module.
10 Answers
...
AngularJS: Service vs provider vs factory
...get(). The constructor function is instantiated before the $get method is called - ProviderFunction is the function reference passed to module.provider.
Providers have the advantage that they can be configured during the module configuration phase.
See here for the provided code.
Here's a great fur...
How to make an OpenGL rendering context with transparent background?
Rendering contexts usually have a solid color on the background (black or whatever, see the image below):
9 Answers
...
AttributeError: 'module' object has no attribute 'tests'
...
I finally figured it out working on another problem. The problem was that my test couldn't find an import.
It looks like you get the above error if your test fails to import. This makes sense because the test suite can't import ...
What is a plain English explanation of “Big O” notation?
...a notation "Θ" (which is a two-side bound). In my experience, this is actually typical of discussions in non-academic settings. Apologies for any confusion caused.
Big O complexity can be visualized with this graph:
The simplest definition I can give for Big-O notation is this:
Big-O notation is ...
Cannot kill Python script with Ctrl-C
...you can't do anything with it after it exits. The process will finish when all non-daemon threads have finished; parent-child relationships don't come into that.
– Thomas K
Dec 6 '13 at 22:22
...
undefined reference to boost::system::system_category() when compiling
...raries. I have the 1.46-dev Boost libraries from the Ubuntu Repository installed, but I get an error when compiling the program.
...