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Nested defaultdict of defaultdict
...
For an arbitrary number of levels:
def rec_dd():
return defaultdict(rec_dd)
>>> x = rec_dd()
>>> x['a']['b']['c']['d']
defaultdict(<function rec_dd at 0x7f0dcef81500>, {})
>>> print json.dumps(x)
{"a": {"b": {"c": {"d": {}}}}}
...
Find the nth occurrence of substring in a string
... more Pythonic version of the straightforward iterative solution:
def find_nth(haystack, needle, n):
start = haystack.find(needle)
while start >= 0 and n > 1:
start = haystack.find(needle, start+len(needle))
n -= 1
return start
Example:
>>> find_nth("fo...
Read-only and non-computed variable properties in Swift
...property which returns that property:
public class Clock {
private var _hours = 0
public var hours: UInt {
return _hours
}
}
But this can be achieved in a different, shorter way, as stated in the section "Access Control" of the "The Swift Programming Language" book:
public class Clo...
Why would you use an ivar?
...d by the compiler may involve another C function call to the functions objc_getProperty/objc_setProperty, as these will have to retain/copy/autorelease the objects as needed and further perform spinlocking for atomic properties where necessary. This can easily get very expensive and I'm not talking ...
In Scala, what exactly does 'val a: A = _' (underscore) mean?
What exactly does val a: A = _ initialize a value to? Is this a typed null? Thanks.
2 Answers
...
What is the difference between old style and new style classes in Python?
...o the concept of type:
if x is an instance of an old-style class, then x.__class__
designates the class of x, but type(x) is always <type
'instance'>.
This reflects the fact that all old-style instances, independently of
their class, are implemented with a single built-in type, c...
node.js require all files in a folder?
....
Working example of a loader:
var normalizedPath = require("path").join(__dirname, "routes");
require("fs").readdirSync(normalizedPath).forEach(function(file) {
require("./routes/" + file);
});
// Continue application logic here
...
jQuery: How can i create a simple overlay?
...ouseenter(showPhotoOverlay);
// Create photo overlay elements
var _isPhotoOverlayDisplayed = false;
var _photoId;
var _photoOverlay = $("<div id='photoOverlay'></div>");
var _photoOverlayShareButton = $("<div id='photoOverlayShare'>Share</div>");
// ...
Python 2.7: Print to File
...If you want to use the print function in Python 2, you have to import from __future__:
from __future__ import print_function
But you can have the same effect without using the function, too:
print >>f1, 'This is a test'
...
What does `:_*` (colon underscore star) do in Scala?
...to the method with repeated parameters (as denoted with Node* above).
The _* type annotation is covered in "4.6.2 Repeated Parameters" of the SLS.
The last value parameter of a parameter section may be suffixed by “*”, e.g. (..., x:T *). The type of such a repeated parameter inside th...