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How can I get the concatenation of two lists in Python without modifying either one? [duplicate]
In Python, the only way I can find to concatenate two lists is list.extend , which modifies the first list. Is there any concatenation function that returns its result without modifying its arguments?
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What are the differences between a pointer variable and a reference variable in C++?
I know references are syntactic sugar, so code is easier to read and write.
41 Answers
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Create a “with” block on several context managers? [duplicate]
Suppose you have three objects you acquire via context manager, for instance A lock, a db connection and an ip socket.
You can acquire them by:
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Thread-safe List property
... Correct, it is a shallow copy. The point was to simply have a cloned set that would be safe to iterate over (so newList does not have any items added or removed which would invalidate the enumerator).
– Tejs
Jan 3 '13 at 18:47
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Run function from the command line
I have this code:
16 Answers
16
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Converting unix timestamp string to readable date
...stamp() might fail for past dates if a local timezone had different utc offset. You need a historic timezone database such as provided by pytz module (or your OS). Or just work in UTC and use .utcfromtimestamp().
– jfs
Nov 23 '13 at 1:08
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git error: failed to push some refs to remote
...Why do I need to explicitly push a new branch?".
Since the OP already reset and redone its commit on top of origin/master:
git reset --mixed origin/master
git add .
git commit -m "This is a new commit for what I originally planned to be amended"
git push origin master
There is no need to pull ...
How do you convert a byte array to a hexadecimal string, and vice versa?
How can you convert a byte array to a hexadecimal string, and vice versa?
45 Answers
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How do you use the ? : (conditional) operator in JavaScript?
...(or want to use) a ternary in a situation like 'display a variable if it's set, else...', you can make it even shorter, without a ternary.
Instead of:
var welcomeMessage = 'Hello ' + (username ? username : 'guest');
You can use:
var welcomeMessage = 'Hello ' + (username || 'guest');
This ...
What is the C# equivalent of NaN or IsNumeric?
What is the most efficient way of testing an input string whether it contains a numeric value (or conversely Not A Number)? I guess I can use Double.Parse or a regex (see below) but I was wondering if there is some built in way to do this, such as javascript's NaN() or IsNumeric() (was that VB...