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Ship an application with a database
...savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
DatabaseHelper myDbHelper;
SQLiteDatabase myDb = null;
myDbHelper = new DatabaseHelper(this);
/*
* Database must be initialized before it can be used. Th...
Maximum single-sell profit
...e problem for the first element, then the first two, then the first three, etc. until we'd computed it for the first n elements.
Let's think about how to do this. If we have just one element, we already know that it has to be the best buy/sell pair. Now suppose we know the best answer for the fir...
What are the underlying data structures used for Redis?
...p List. Hashes are flattened into a list like [key1, value1, key2, value2] etc.
With Zip Lists you have the power to make a tradeoff between CPU and Memory. Zip Lists are memory-efficient, but they use more CPU than a linked list (or Hash table/Skip List). Finding an element in the zip list is O(n)...
What are metaclasses in Python?
...relying on introspection, manipulating inheritance, vars such as __dict__, etc.
Indeed, metaclasses are especially useful to do black magic, and therefore
complicated stuff. But by themselves, they are simple:
intercept a class creation
modify the class
return the modified class
Why would you use ...
ObservableCollection Doesn't support AddRange method, so I get notified for each item added, besides
...lection from below in WPF UI-related work, such as binding it to a ListBox etc. (you can still use the ObservableRangeCollection<T> if not bound to UI).
However you can use the WpfObservableRangeCollection<T> workaround.
The real solution would be creating a CollectionView that knows how...
How do I pass a unique_ptr argument to a constructor or a function?
... that you are transferring ownership of the pointer to the function/object/etc in question. After newBase is constructed, nextBase is guaranteed to be empty. You don't own the object, and you don't even have a pointer to it anymore. It's gone.
This is ensured because we take the parameter by value....
How to make a chain of function decorators?
...idon!
Python itself provides several decorators: property, staticmethod, etc.
Django uses decorators to manage caching and view permissions.
Twisted to fake inlining asynchronous functions calls.
This really is a large playground.
...
Git and Mercurial - Compare and Contrast
...refs residing in refs/tags/ namespace, and by default are autofollowed on fetching and require explicit pushing.
Branches: In Mercurial basic workflow is based on anonymous heads; Git uses lightweight named branches, and has special kind of branches (remote-tracking branches) that follow branches in...
What optimizations can GHC be expected to perform reliably?
...many other possibilities - map followed by filter, filter followed by map, etc. Rather than hand-code a solution for each of them, so-called "stream fusion" was invented. This is a more complicated trick, which I won't describe here.
The long and short of it is: These are all special optimisation t...
How to write a scalable Tcp/Ip based server
... break;
}
if (e.Buffer[i] == (int)TelnetCommand.IAC)
{
TelnetCommand command = (TelnetCommand)e.Buffer[i + 1];
TelnetOption option = (TelnetOption)e.Buffer[i + 2];
switch (command)
{
...