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Does SQLAlchemy have an equivalent of Django's get_or_create?
...odel, defaults=None, **kwargs):
instance = session.query(model).filter_by(**kwargs).first()
if instance:
return instance, False
else:
params = dict((k, v) for k, v in kwargs.iteritems() if not isinstance(v, ClauseElement))
params.update(defaults or {})
ins...
When to use ' (or quote) in Lisp?
...
Short answer
Bypass the default evaluation rules and do not evaluate the expression (symbol or s-exp), passing it along to the function exactly as typed.
Long Answer: The Default Evaluation Rule
When a regular (I'll come to that later) ...
Can git undo a checkout of unstaged files
... yet added (staged), it is purely "private".
Meaning it cannot be restored by GIT if overwritten with the index or the HEAD version (unless you have a copy of your current work somewhere).
A "private" content is one only visible in your current directory, but not registered in any way in Git.
Note: ...
Efficient way to return a std::vector in c++
...1, this is the preferred way:
std::vector<X> f();
That is, return by value.
With C++11, std::vector has move-semantics, which means the local vector declared in your function will be moved on return and in some cases even the move can be elided by the compiler.
...
How does git compute file hashes?
The SHA1 hashes stored in the tree objects (as returned by git ls-tree ) do not match the SHA1 hashes of the file content (as returned by sha1sum )
...
pycharm running way slow
I'm a big fan of PyCharm by JetBrains but I do run into some issues that I thought maybe I'll ask here about.
9 Answers
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How to profile a bash shell script slow startup?
.... Change the setting of PS4:
PS4='+ $EPOCHREALTIME\011 '
As pointed out by @pawamoy, you can use BASH_XTRACEFD to send the output of the trace to a separate file descriptor if you have Bash 4.1 or later. From this answer:
#!/bin/bash
exec 5> command.txt
BASH_XTRACEFD="5"
echo -n "hello "
s...
Is there a way for multiple processes to share a listening socket?
...arent/child processes need to work out which handle needs to be duplicated by some IPC mechanism (although this could be as simple as a file in the filesystem)
CLARIFICATION:
In answer to the OP's original question, no, multiple processes cannot bind(); just the original parent process would call ...
What is the difference between “Class.forName()” and “Class.forName().newInstance()”?
...alling clazz.newInstance() creates a new instance of the class represented by this Class object. The class is instantiated as if by a new expression with an empty argument list. In other words, this is here actually equivalent to a new Demo() and returns a new instance of Demo.
And running this De...
Push git commits & tags simultaneously
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Update August 2020
As mentioned originally in this answer by SoBeRich, and in my own answer, as of git 2.4.x
git push --atomic origin <branch name> <tag>
(Note: this actually work with HTTPS only with Git 2.24)
Update May 2015
As of git 2.4.1, you can do
git config --gl...