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How to use performSelector:withObject:afterDelay: with primitive types in Cocoa?
...trick if it is a BOOL parameter.
Pass nil for NO and self for YES. nil is cast to the BOOL value of NO. self is cast to the BOOL value of YES.
This approach breaks down if it is anything other than a BOOL parameter.
Assuming self is a UIView.
//nil will be cast to NO when the selector is perform...
动态追踪（Dynamic Tracing）技术漫谈 - 操作系统(内核) - 清泛网 - 专注C/C++及内核技术
动态追踪（Dynamic Tracing）技术漫谈dynamic-tracing什么是动态追踪动态追踪的优点DTrace 与 SystemTapSystemTap 在生产上的应用火焰图方法论知识就是力量开源与调试符号Linux 内核的支持硬件追踪死亡进程的遗骸分析传统的调试技
什么...
How do short URLs services work?
...n the database, they find a description (sometimes), your name (sometimes) and the real URL. Then they issue a redirect, which is a HTTP 302 response and the target URL in the header.
This direct redirect is important. If you were to use files or first load HTML and then redirect, the browser would...
Illegal mix of collations (utf8_unicode_ci,IMPLICIT) and (utf8_general_ci,IMPLICIT) for operation '=
...s not suffer of performance issues.
Using Option 1 and 2, aka the COLLATE cast approach, can lead to potential bottleneck, cause any index defined on the column will not be used causing a full scan.
Even though I did not try out Option 3, my hunch is that it will suffer the same consequences of op...
Passing a single item as IEnumerable
...f you pass in a list or an array, then an unscrupulous piece of code could cast it and change the contents, leading to odd behaviour in some situations. You could use a read-only collection, but that's likely to involve even more wrapping. I think your solution is as neat as it gets.
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Is there a Python equivalent to Ruby's string interpolation?
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@Caste see here: docs.python.org/library/stdtypes.html#string-formatting and post a follow up comment if you need any more details
– mikej
Dec 15 '10 at 13:59
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Cannot create an array of LinkedLists in Java…?
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For some reason you have to cast the type and make the declaration like this:
myMatrix = (LinkedList<IntegerNode>[]) new LinkedList<?>[numRows];
share
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What is a raw type and why shouldn't we use it?
... String name = (String) o;
System.out.println(name);
} // throws ClassCastException!
// java.lang.Boolean cannot be cast to java.lang.String
Now we run into trouble at run-time, because names contains something that isn't an instanceof String.
Presumably, if you want names to contain only...
How to do ToString for a possibly null object?
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C# 6.0 Edit:
With C# 6.0 we can now have a succinct, cast-free version of the orignal method:
string s = myObj?.ToString() ?? "";
Or even using interpolation:
string s = $"{myObj}";
Original Answer:
string s = (myObj ?? String.Empty).ToString();
or
string s = (myObjc ?? "")....
What are POD types in C++?
...en pointers to vtables, offsets that get applied to the address when it is cast to other types (at least if the target's POD too), constructors, or destructors. Roughly speaking, a type is a POD when the only things in it are built-in types and combinations of them. The result is something that "act...