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SQLAlchemy: What's the difference between flush() and commit()?
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Hopefully this example will make this clearer:
#---
s = Session()
s.add(Foo('A')) # The Foo('A') object has been added to the session.
# It has not been committed to the database yet,
# but is returned as part of a query.
print 1, s.query(Foo).all()
s.commit()
#...
Check whether a variable is a string in Ruby
...return true for instances from derived classes.
class X < String
end
foo = X.new
foo.is_a? String # true
foo.kind_of? String # true
foo.instance_of? String # false
foo.instance_of? X # true
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Use git “log” command in another folder
...with the --git-dir parameter, before passing any commands.
git --git-dir /foo/bar/.git log
(Specifying the .git directory is necessary.) From the documentation:
--git-dir=<path>
Set the path to the repository. This can also be controlled by setting the GIT_DIR environment variable....
Which is better in python, del or delattr?
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The first is more efficient than the second. del foo.bar compiles to two bytecode instructions:
2 0 LOAD_FAST 0 (foo)
3 DELETE_ATTR 0 (bar)
whereas delattr(foo, "bar") takes five:
2 0 LOAD_GLOBAL ...
C# member variable initialization; best practice?
...rties (field initializers cannot) - i.e.
[DefaultValue("")]
public string Foo {get;set;}
public Bar() { // ctor
Foo = "";
}
Other than that, I tend to prefer the field initializer syntax; I find it keeps things localized - i.e.
private readonly List<SomeClass> items = new List<SomeCla...
sed command with -i option (in-place editing) works fine on Ubuntu but not Mac [duplicate]
...nt of this GNU sed (standard on most Linux distros) command:
sed -i 's/foo/bar/' file
is this BSD/macOS sed command:
sed -i '' 's/foo/bar/' file # Note the '' as a *separate argument*
With BSD/macOS sed, the following commands do not work at all or not as intended:
sed -i 's/foo/bar/' ...
Any equivalent to .= for adding to beginning of string in PHP?
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Nope. But you can do
$foo = "bar" . $foo
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How can I escape square brackets in a LIKE clause?
...acter in a range or set. For example, using LIKE '[fz]oo' will match both 'foo' and 'zoo'.
– Holistic Developer
Feb 1 '17 at 17:18
4
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How do I move an existing Git submodule within a Git repository?
...h that path configuration and the submodule's name. For example, in moving foo/module to bar/module you must change in .gitmodules the section [submodule "foo/module"] to [submodule "bar/module"], and under that same section path = foo/module to path = bar/module. Also, you must change in .git/confi...
Swapping column values in MySQL
...wapping string values)
mysql> select * from swapper;
+------+------+
| foo | bar |
+------+------+
| 6 | 1 |
| 5 | 2 |
| 4 | 3 |
+------+------+
3 rows in set (0.00 sec)
mysql> update swapper set
-> foo = concat(foo, "###", bar),
-> bar = replace(foo, co...