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If table exists drop table then create it, if it does not exist just create it
...s case than not to cover, see locking note below).
Second RENAME ... atomically replaces table definition, refer to
MySQL manual
for details.
At last, DROP ... just cleans up the old table,
obviously.
Wrapping all statements with something like SELECT GET_LOCK('__upgrade', -1); ... DO RELEASE_LOCK...
How to check if all elements of a list matches a condition?
...
The best answer here is to use all(), which is the builtin for this situation. We combine this with a generator expression to produce the result you want cleanly and efficiently. For example:
>>> items = [[1, 2, 0], [1, 2, 0], [1, 2, 0]]
>>...
What is the id( ) function used for?
... Python objects.
Is it the same with memory addresses in C?
Conceptually, yes, in that they are both guaranteed to be unique in their universe during their lifetime. And in one particular implementation of Python, it actually is the memory address of the corresponding C object.
If yes, wh...
How to convert an xml string to a dictionary?
... first two tags
# in a series are different, then they are all different.
if len(element) == 1 or element[0].tag != element[1].tag:
aDict = XmlDictConfig(element)
# treat like list - we assume that if the first two tags
...
How do you 'redo' changes after 'undo' with Emacs?
...ven a navigation command such as C-f) after a sequence of undo operations, all the undos are pushed on to the operation stack. So the next undo undoes the last command. Suppose you do have an operation sequence that looks like this:
Insert "foo"
Insert "bar"
Insert "I love spam"
Now, you undo....
How do I check if there are duplicates in a flat list?
...
Use set() to remove duplicates if all values are hashable:
>>> your_list = ['one', 'two', 'one']
>>> len(your_list) != len(set(your_list))
True
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...
background function in Python
...em is. I've got a function that downloads the image needed and saves it locally. Right now it's run inline with the code that displays a message to the user, but that can sometimes take over 10 seconds for non-local images. Is there a way I could call this function when it's needed, but run it in t...
I want to delete all bin and obj folders to force all projects to rebuild everything
I work with multiple projects, and I want to recursively delete all folders with the name 'bin' or 'obj' that way I am sure that all projects will rebuild everything (sometimes it's the only way to force Visual Studio to forget all about previous builds).
...
super() fails with error: TypeError “argument 1 must be type, not classobj” when parent does not inh
...ss. Change it like so:
class B(object):
and it will work.
super() and all subclass/superclass stuff only works with new-style classes. I recommend you get in the habit of always typing that (object) on any class definition to make sure it is a new-style class.
Old-style classes (also known as...
Python Dictionary Comprehension
...>> print d
{0: 0, 1: 1, 2: 4, 3: 9, 4: 16}
If you want to set them all to True:
>>> d = {n: True for n in range(5)}
>>> print d
{0: True, 1: True, 2: True, 3: True, 4: True}
What you seem to be asking for is a way to set multiple keys at once on an existing dictionary. ...