Tutorial by Examples: en

The idea here is to move the computationally intensive jobs to C (using special macros), independent of Python, and have the C code release the GIL while it's working. #include "Python.h" ... PyObject *pyfunc(PyObject *self, PyObject *args) { ... Py_BEGIN_ALLOW_THREADS //...

Because LINQ uses deferred execution, we can have a query object that doesn't actually contain the values, but will return the values when evaluated. We can thus dynamically build the query based on our control flow, and evaluate it once we are finished: IEnumerable<VehicleModel> BuildQuery(i...

If the help function is called in the console without any arguments, Python presents an interactive help console, where you can find out about Python modules, symbols, keywords and more. >>> help() Welcome to Python 3.4's help utility! If this is your first time using Python, you sho...

The console for the primary version of Python can usually be opened by typing py into your windows console or python on other platforms. $ py Python 3.4.3 (v3.4.3:9b73f1c3e601, Feb 24 2015, 22:44:40) [MSC v.1600 64 bit (AMD64)] on win32 Type "help", "copyright", "credits&...

Python has a variety of command-line switches which can be passed to py. These can be found by performing py --help, which gives this output on Python 3.4: Python Launcher usage: py [ launcher-arguments ] [ python-arguments ] script [ script-arguments ] Launcher arguments: -2 : Launch ...

A simple static file server would look like this: package main import ( "net/http" ) func main() { muxer := http.NewServeMux() fileServerCss := http.FileServer(http.Dir("src/css")) fileServerJs := http.FileServer(http.Dir("src/js")) file...

You can use the star * when writing a function to collect all positional (ie. unnamed) arguments in a tuple: def print_args(farg, *args): print("formal arg: %s" % farg) for arg in args: print("another positional arg: %s" % arg) Calling method: print_args(1, &...

You can define a function that takes an arbitrary number of keyword (named) arguments by using the double star ** before a parameter name: def print_kwargs(**kwargs): print(kwargs) When calling the method, Python will construct a dictionary of all keyword arguments and make it available in ...

A common use case for *args in a function definition is to delegate processing to either a wrapped or inherited function. A typical example might be in a class's __init__ method class A(object): def __init__(self, b, c): self.y = b self.z = c class B(A): def __init__(...

You can use a dictionary to assign values to the function's parameters; using parameters name as keys in the dictionary and the value of these arguments bound to each key: def test_func(arg1, arg2, arg3): # Usual function with three arguments print("arg1: %s" % arg1) print("a...

Postfix increment X++ will add 1 to x var x = 42; x++; Console.WriteLine(x); // 43 Postfix decrement X-- will subtract one var x = 42 x--; Console.WriteLine(x); // 41 ++x is called prefix increment it increments the value of x and then returns x while x++ returns the value of x and the...

Introduce environment variable VAGRANT_DEFAULT_PROVIDER export VAGRANT_DEFAULT_PROVIDER=vmware_fusion

NSString *testString = @"There are 42 sheep and 8672 cows."; NSError *error = nil; NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"(\\d+)" options:NSRegularExpressionCaseIns...

Generates a storable representation of a value. This is useful for storing or passing PHP values around without losing their type and structure. To make the serialized string into a PHP value again, use unserialize(). Serializing a string $string = "Hello world"; echo serialize($s...

Problem # models.py: class Library(models.Model): name = models.CharField(max_length=100) books = models.ManyToManyField(Book) class Book(models.Model): title = models.CharField(max_length=100) # views.py def myview(request): # Query the database. libraries = Librar...

Problem Django querysets are evaluated in a lazy fashion. For example: # models.py: class Author(models.Model): name = models.CharField(max_length=100) class Book(models.Model): author = models.ForeignKey(Author, related_name='books') title = models.CharField(max_length=100) ...

Python 2.x2.7 In Python 2 filter, map and zip built-in functions return a sequence. map and zip always return a list while with filter the return type depends on the type of given parameter: >>> s = filter(lambda x: x.isalpha(), 'a1b2c3') >>> s 'abc' >>> s = map(lambd...

public class Foo { private const int TASK_ITERATION_DELAY_MS = 1000; private CancellationTokenSource _cts; public Foo() { this._cts = new CancellationTokenSource(); } public void StartExecution() { Task.Factory.StartNew(this.OwnCodeCancelable...

public class Foo { private CancellationTokenSource _cts; public Foo() { this._cts = new CancellationTokenSource(); } public void StartExecution() { Task.Factory.StartNew(this.OwnCodeCancelableTask, this._cts.Token); } public void Cance...

Unlike durations, periods can be used to accurately model clock times without knowing when events such as leap seconds, leap days, and DST changes occur. start_2012 <- ymd_hms("2012-01-01 12:00:00") ## [1] "2012-01-01 12:00:00 UTC" # period() considers leap year calculati...