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What are some (concrete) use-cases for metaclasses?
...ase classes' attributes every time):
>>> class A(Model):
... foo = Integer()
...
>>> class B(A):
... bar = String()
...
>>> B._fields
{'foo': Integer('A.foo'), 'bar': String('B.bar')}
Again, this can be done (without inheritance) with a class decorator:
def mod...
Overriding a Rails default_scope
...
In Rails 3:
foos = Foo.unscoped.where(:baz => baz)
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PHP Fatal error: Using $this when not in object context
...
In my index.php I'm loading maybe
foobarfunc() like this:
foobar::foobarfunc(); // Wrong, it is not static method
but can also be
$foobar = new foobar; // correct
$foobar->foobarfunc();
You can not invoke method this way because it is not sta...
What is setup.py?
...
It helps to install a python package foo on your machine (can also be in virtualenv) so that you can import the package foo from other projects and also from [I]Python prompts.
It does the similar job of pip, easy_install etc.,
Using setup.py
Let's star...
Linux: copy and create destination dir if it does not exist
...ating any
missing intermediate directories.
Example:
/tmp $ mkdir foo
/tmp $ mkdir foo/foo
/tmp $ touch foo/foo/foo.txt
/tmp $ mkdir bar
/tmp $ cp --parents foo/foo/foo.txt bar
/tmp $ ls bar/foo/foo
foo.txt
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Why does += behave unexpectedly on lists?
...unction will append all elements of the parameter to the list.
When doing foo += something you're modifying the list foo in place, thus you don't change the reference that the name foo points to, but you're changing the list object directly. With foo = foo + something, you're actually creating a ne...
class
...
First, the class << foo syntax opens up foo's singleton class (eigenclass). This allows you to specialise the behaviour of methods called on that specific object.
a = 'foo'
class << a
def inspect
'"bar"'
end
end
a.inspect # =>...
SQL keys, MUL vs PRI vs UNI
...s example has neither PRI, MUL, nor UNI:
mysql> create table penguins (foo INT);
Query OK, 0 rows affected (0.01 sec)
mysql> desc penguins;
+-------+---------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------+------+-----+---------+-------+...
Unsubscribe anonymous method in C#
... was to unsubscribe after the event was handled.
Example:
MyEventHandler foo = null;
foo = delegate(object s, MyEventArgs ev)
{
Console.WriteLine("I did it!");
MyEvent -= foo;
};
MyEvent += foo;
sh...
p vs puts in Ruby
...
p foo prints foo.inspect followed by a newline, i.e. it prints the value of inspect instead of to_s, which is more suitable for debugging (because you can e.g. tell the difference between 1, "1" and "2\b1", which you can't when...