大约有 42,000 项符合查询结果（耗时：0.0698秒） [XML]
the item you requested is not available for purchase
I'm trying to integrate Android Market in-app purchases into my app, but unfortunately coming across an annoying error every time I try to purchase a real inapp product.
...
What's the best name for a non-mutating “add” method on an immutable collection?
...
Unless I'm missing it, System.Linq.Enumerable (and Linq in general) only uses Concat() for "sequence + sequence", never "item + sequence". The problem that someone "might expect it to add two lists together rather than adding a single value to the other list" was explici...
Memoization in Haskell?
...f :: Int -> Int
faster_f n = f_list !! n
That performs passably well, and replaces what was going to take O(n^3) time with something that memoizes the intermediate results.
But it still takes linear time just to index to find the memoized answer for mf. This means that results like:
*Main Dat...
How do I alter the position of a column in a PostgreSQL database table?
...e column order is either by
recreating the table, or by adding
columns and rotating data until you
reach the desired layout.
That's pretty weak, but in their defense, in standard SQL, there is no solution for repositioning a column either. Database brands that support changing the ordinal p...
How do I show the changes which have been staged?
...s) against the current HEAD. --staged is a synonym for --cached.
--staged and --cached does not point to HEAD, just difference with respect to HEAD. If you cherry pick what to commit using git add --patch (or git add -p), --staged will return what is staged.
...
How to implement has_many :through relationships with Mongoid and mongodb?
...ther side. For example:
class Physician
include Mongoid::Document
has_and_belongs_to_many :patients
end
class Patient
include Mongoid::Document
has_and_belongs_to_many :physicians
end
In other words you would eliminate the join table and it would have a similar effect to has_many :throug...
How to automatically crop and center an image
... any arbitrary image, I want to crop a square from the center of the image and display it within a given square.
7 Answers
...
How do I correctly clean up a Python object?
__del__(self) above fails with an AttributeError exception. I understand Python doesn't guarantee the existence of "global variables" (member data in this context?) when __del__() is invoked. If that is the case and this is the reason for the exception, how do I make sure the object destructs...
What does “=>” mean in PHP?
...the context of that foreach loop, it assigns the key of the array to $user and the value to $pass.
Example:
$user_list = array(
'dave' => 'apassword',
'steve' => 'secr3t'
);
foreach ($user_list as $user => $pass) {
echo "{$user}'s pass is: {$pass}\n";
}
// Prints:
// "dave's...
What is the cleanest way to get the progress of JQuery ajax request?
...ng a request, processing the request in the backend to generate some data, and return it back. How can the client side possibly know what is being done in the backend and how much time it will take that it can calculate the progress?
– SexyBeast
Apr 30 '17 at 2...