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add column to mysql table if it does not exist
...
Note that INFORMATION_SCHEMA isn't supported in MySQL prior to 5.0. Nor are stored procedures supported prior to 5.0, so if you need to support MySQL 4.1, this solution isn't good.
One solution used by frameworks that use database migrations is...
Markdown and including multiple files
...e, if you were creating a book, then you could have chapters like this:
01_preface.md
02_introduction.md
03_why_markdown_is_useful.md
04_limitations_of_markdown.md
05_conclusions.md
You can merge them by doing executing this command within the same directory:
pandoc *.md > markdown_book.html
...
Socket.IO - how do I get a list of connected sockets/clients?
...lients('room');
anymore. Instead you can use the following
var clients_in_the_room = io.sockets.adapter.rooms[roomId];
for (var clientId in clients_in_the_room ) {
console.log('client: %s', clientId); //Seeing is believing
var client_socket = io.sockets.connected[clientId];//Do whatever y...
How can I hash a password in Java?
...m recommended cost, used by default
*/
public static final int DEFAULT_COST = 16;
private static final String ALGORITHM = "PBKDF2WithHmacSHA1";
private static final int SIZE = 128;
private static final Pattern layout = Pattern.compile("\\$31\\$(\\d\\d?)\\$(.{43})");
private final Se...
Iterate a list as pair (current, next) in Python
...
Since the_list[1:] actually creates a copy of the whole list (excluding its first element), and zip() creates a list of tuples immediately when called, in total three copies of your list are created. If your list is very large, you ...
How do you test that a Python function throws an exception?
...t ahold of the actual Exception object thrown:
import unittest
def broken_function():
raise Exception('This is broken')
class MyTestCase(unittest.TestCase):
def test(self):
with self.assertRaises(Exception) as context:
broken_function()
self.assertTrue('This i...
What is the combinatory logic equivalent of intuitionistic type theory?
... bracket abstraction.
tm :: Tm a -> Unty a
tm (Var a) = V a
tm (Lam _ b) = bra (tm b)
tm (f :$ a) = tm f :. tm a
tm (Pi a b) = C P :. tm a :. tm b
tm Set = C U
bra :: Unty (Su a) -> Unty a -- binds a variable, building a function
bra (V Ze) = C S :. C K :. C...
What is the single most influential book every programmer should read? [closed]
... For Computer Scientists http://ecx.images-amazon.com/images/I/51HCJ5R42KL._SL500_BO2,204,203,200_AA219_PIsitb-sticker-dp-arrow,TopRight,-24,-23_SH20_OU02_.jpg
Discrete Mathematics For Computer Scientists by J.K. Truss.
While this doesn't teach you programming, it teaches you fundamental mathemati...
Pythonic way to print list items
...myList, sep='\n')
You can get the same behavior on Python 2.x using from __future__ import print_function, as noted by mgilson in comments.
With the print statement on Python 2.x you will need iteration of some kind, regarding your question about print(p) for p in myList not working, you can just...
Adding information to an exception?
....message +
' happens at %s' % arg1), sys.exc_info()[2]
bar('arg1')
Traceback (most recent call last):
File "test.py", line 16, in <module>
bar('arg1')
File "test.py", line 11, in bar
foo()
File "test.py", line 5, in foo
raise IOError('Stuff...