大约有 40,000 项符合查询结果（耗时：0.0362秒） [XML]
MySQL, update multiple tables with one query
...ookID is very important, without it The Books table update would happen to all rows and not only for the row with the specified id. Some lessons are learned the hard way, this one was learned in the terrifing way.
– nheimann1
Mar 24 '15 at 15:06
...
Iterating over Java collections in Scala
...
As of Scala 2.8, all you have to do is to import the JavaConversions object, which already declares the appropriate conversions.
import scala.collection.JavaConversions._
This won't work in previous versions though.
...
In Python, when should I use a function instead of a method?
...sulation which is so dear to OO design.
The encapsulation principal is really what this comes down to: as a designer you should hide everything about the implementation and class internals which it is not absolutely necessarily for any user or other developer to access. Because we deal with instan...
Finding the index of elements based on a condition using python list comprehension
...
In Python, you wouldn't use indexes for this at all, but just deal with the values—[value for value in a if value > 2]. Usually dealing with indexes means you're not doing something the best way.
If you do need an API similar to Matlab's, you would use numpy, a packag...
Setting the correct encoding when piping stdout in Python
...you must encode it yourself.
A rule of thumb is: Always use Unicode internally. Decode what you receive, and encode what you send.
# -*- coding: utf-8 -*-
print u"åäö".encode('utf-8')
Another didactic example is a Python program to convert between ISO-8859-1 and UTF-8, making everything upper...
How can I print the contents of a hash in Perl?
I keep printing my hash as # of buckets / # allocated.
How do I print the contents of my hash?
11 Answers
...
How does BLAS get such extreme performance?
...e optimization. This boost significantly exceeds the second boost from parallelism and other hardware optimizations.
By the way, most (or even all) of the high performance BLAS implementations are NOT implemented in Fortran. ATLAS is implemented in C. GotoBLAS/OpenBLAS is implemented in C and i...
Read-only and non-computed variable properties in Swift
...g in Objective-C. I have readonly properties, and they cannot be individually changed. However, using a specific method, the properties are changed in a logical way.
...
Unsupported major.minor version 52.0 [duplicate]
...
"J2SE" was only used till Java 1.5 and is nowadays called "Java SE", see en.wikipedia.org/wiki/Java_Platform,_Standard_Edition
– Tim Büthe
Sep 6 '16 at 14:38
...
Case objects vs Enumerations in Scala
... deal with an Option[Currency] type that would clearly indicate there is really a matching problem and "encourage" the user of the API to sort it out him/herself.
To follow up on the other answers here, the main drawbacks of case objects over Enumerations are:
Can't iterate over all instances of t...