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When is “i += x” different from “i = i + x” in Python?
...This depends entirely on the object i.
+= calls the __iadd__ method (if it exists -- falling back on __add__ if it doesn't exist) whereas + calls the __add__ method1 or the __radd__ method in a few cases2.
From an API perspective, __iadd__ is supposed to be used for modifying mutable objects i...
Interfaces with static fields in java for sharing 'constants'
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It's generally considered bad practice. The problem is that the constants are part of the public "interface" (for want of a better word) of the implementing class. This means that the implementing class is publishing all of...
findViewByID returns null
... I read all the other threads on this topic. And not only those from this site... (you see, I'm a little frustrated)
29 Ans...
What does Serializable mean?
What exactly does it mean for a class to be Serializable in Java? Or in general, for that matter...
10 Answers
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How to create GUID / UUID?
... are identifiers designed to provide certain uniqueness guarantees.
While it is possible to implement an RFC-compliant UUIDs in a few lines of JS (E.g. see @broofa's answer, below) there are several common pitfalls:
Invalid id format (UUIDs must be of the form "xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxx...
Why don't structs support inheritance?
I know that structs in .NET do not support inheritance, but its not exactly clear why they are limited in this way.
10 An...
'Static readonly' vs. 'const'
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public static readonly fields are a little unusual; public static properties (with only a get) would be more common (perhaps backed by a private static readonly field).
const values are burned directly into the call-site; this is double edged:
it is useless i...
What is the tilde (~) in the enum definition?
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~ is the unary one's complement operator -- it flips the bits of its operand.
~0 = 0xFFFFFFFF = -1
in two's complement arithmetic, ~x == -x-1
the ~ operator can be found in pretty much any language that borrowed syntax from C, including Objective-C/C++/C#/Java/Java...
Performance of Arrays vs. Lists
Say you need to have a list/array of integers which you need iterate frequently, and I mean extremely often. The reasons may vary, but say it's in the heart of the inner most loop of a high volume processing.
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Where do “pure virtual function call” crashes come from?
I sometimes notice programs that crash on my computer with the error: "pure virtual function call".
8 Answers
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