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Why are preprocessor macros evil and what are the alternatives?
... never received a really good answer; I think that almost any programmer before even writing the first "Hello World" had encountered a phrase like "macro should never be used", "macro are evil" and so on, my question is: why? With the new C++11 is there a real alternative after so many years?
...
Why do we need extern “C”{ #include } in C++?
... expects the data contained in the header file to be compiled to a certain format—the C++ 'ABI', or 'Application Binary Interface', so the linker chokes up. This is preferable to passing C++ data to a function expecting C data.
(To get into the really nitty-gritty, C++'s ABI generally 'mangles' t...
How to write to a file, using the logging Python module?
...ame,
filemode='a',
format='%(asctime)s,%(msecs)d %(name)s %(levelname)s %(message)s',
datefmt='%H:%M:%S',
level=logging.DEBUG)
logging.info("Running Urban Planning")
self.logger = loggin...
Best way to select random rows PostgreSQL
...equential scan of the big table, only an index scan.
First, get estimates for the main query:
SELECT count(*) AS ct -- optional
, min(id) AS min_id
, max(id) AS max_id
, max(id) - min(id) AS id_span
FROM big;
The only possibly expensive part is the count(*) (for h...
What is the purpose of python's inner classes?
...onic: "Namespaces are one honking great idea -- let's do more of those!". For example, consider a DataLoader class that can throw a CacheMiss exception. Nesting the exception under the main class as DataLoader.CacheMiss means you can import just DataLoader but still use the exception.
...
addEventListener not working in IE8
...lse {
_checkbox.attachEvent("onclick", setCheckedValues);
}
Update::
For Internet Explorer versions prior to IE9, attachEvent method should be used to register the specified listener to the EventTarget it is called on, for others addEventListener should be used.
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not None test in Python [duplicate]
...
if val is not None:
# ...
is the Pythonic idiom for testing that a variable is not set to None. This idiom has particular uses in the case of declaring keyword functions with default parameters. is tests identity in Python. Because there is one and only one instance of Non...
bpftrace教程【官方】 - 操作系统(内核) - 清泛网 - 专注C/C++及内核技术
...ore a start timestamp to each. How? We could construct a unique identifier for each read, and use that as the key. But because kernel threads can only be executing one syscall at a time, we can use the thread ID as the unique identifier, as each thread cannot be executing more than one.
nsecs: 自...
Multiple commands in gdb separated by some sort of delimiter ';'?
...
And if you forget how you defined a function, you can use show user <function name> to see its source, e.g. show user fn.
– ntc2
Dec 27 '16 at 22:17
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What is the difference between AF_INET and PF_INET in socket programming?
... thought that maybe a address family (what the "AF" in "AF_INET" stands
for) might support several protocols that were referenced by their
protocol family (what the "PF" in "PF_INET" stands for).
That didn't happen. Oh well. So the correct thing to do is to use AF_INET in your
struct sockad...