大约有 16,000 项符合查询结果（耗时：0.0310秒） [XML]
What is the purpose of willSet and didSet in Swift?
...In Swift an iVar or instance variable is named stored property
Example 1 (read only property) - with warning:
var test : Int {
get {
return test
}
}
This will result in a warning because this results in a recursive function call (the getter calls itself).The warning in this case ...
Can I have multiple primary keys in a single table?
...width of our non-clustered leaf nodes, increasing storage requirements and read accesses for seeks and scans of that non-clustered index; and (2) reduces fan-out from our clustered index increasing index height and index size, again increasing reads and storage requirements for our clustered indexes...
How do I force Postgres to use a particular index?
...ate drives
As the documentation admits:
Storage that has a low random read cost relative to sequential, e.g. solid-state drives, might be better modeled with a lower value for random_page_cost.
According to the last point of this slide from a speak at PostgresConf 2018, random_page_cost shoul...
How to send an email with Python?
...ll need
from email.mime.text import MIMEText
# Open a plain text file for reading. For this example, assume that
# the text file contains only ASCII characters.
with open(textfile, 'rb') as fp:
# Create a text/plain message
msg = MIMEText(fp.read())
# me == the sender's email address
# yo...
What is the entry point of swift code execution?
...
You may want to read Files and Initialization
The exception is a special file named “main.swift”, which behaves much
like a playground file, but is built with your app’s source code. The
“main.swift” file can contain top-le...
Understanding MongoDB BSON Document size limit
...g post is that long with
that many comments, I for one am not
going to read it :)
For trackbacks, if you dedicated 1MB
to them, you could easily have more
than 10k (probably closer to 20k)
So except for truly bizarre
situations, it'll work great. And in
the exception case or sp...
getting exception “IllegalStateException: Can not perform this action after onSaveInstanceState”
... what I can remember. But if you still have issues with this you MUST also read @AlexLockwood 's blog : Fragment Transactions & Activity State Loss
Summary from the blog post (but I strongly recommend you to read it) :
NEVER commit() transactions after onPause() on pre-Honeycomb, and onStop() ...
Batch equivalent of Bash backticks
...you have to clean up after yourself; this very example only enables you to read the very first line of input. For all practical purposes the for /f variant is a much better one.
– Joey
May 4 '10 at 21:33
...
How do SQL EXISTS statements work?
...
I think my confusion might be that I've read that the subquery with an EXISTS returns true or false; but this can't be the only thing that it returns, right? Is the subquery also returning all "suppliers who have corresponding rows in the orders table"? But if it i...
Is there a good tutorial on MSBuild scripts? [closed]
...nying MSBuild v4.0.
There is not much code there though.
It wasn't until reading this blog that I understood that the *.csproj files themselves are MSBuild files. And also, that the Build, Clean, Rebuild and Publish command in the project context menu actually are MSBuild "targets".
...