Tutorial by Examples: g

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 ...

The Python console adds a new function, help, which can be used to get information about a function or object. For a function, help prints its signature (arguments) and its docstring, if the function has one. >>> help(print) Help on built-in function print in module builtins: print(.....

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...

Sometimes you need to keep a linear (non-branching) history of your code commits. If you are working on a branch for a while, this can be tricky if you have to do a regular git pull since that will record a merge with upstream. [alias] up = pull --rebase This will update with your upstream so...

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...

NSLog(@"%s %@",__FUNCTION__, @"etc etc"); Inserts the class and method name into the output: 2016-07-22 12:51:30.099 loggingExample[18132:2971471] -[ViewController viewDidLoad] etc etc

You have a local vagrant box that you want to upload to Amazon AWS. First, you need to create a .box file: vagrant package --base my-virtual-machine This step should take a while depending on the size of your image. Then, you need to get the .vmdk image from the .box file: gunzip -S .box packag...

GridPane lays out its children within a flexible grid of rows and columns. Children of the GridPane A child may be placed anywhere within the GridPane and may span multiple rows/columns (default span is 1) and its placement within the grid is defined by it's layout constraints: ConstraintDescript...

Vagrant.configure("2") do |config| # ... other config up here config.vm.provider "vmware_fusion" end

Instead of the usual loosely typed: @Html.ActionLink("Log in", "UserController", "LogIn") You can now make action links strongly typed: @Html.ActionLink("Log in", @typeof(UserController), @nameof(UserController.LogIn)) Now if you want to refactor your ...

vagrant snapshot restore --no-provision mysnapshot

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

NSString *testString1 = @"(555) 123-5678"; NSString *testString2 = @"not a phone number"; NSError *error = nil; NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"^\\(\\d{3}\\) \\d{3}\\-\\d{4}$" ...

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) ...

C++17 Normally, elision is an optimization. While virtually every compiler support copy elision in the simplest of cases, having elision still places a particular burden on users. Namely, the type who's copy/move is being elided must still have the copy/move operation that was elided. For example:...

The bisect command helps you to track down the changeset that introduced a bug. Reset the bisect state and mark the current revision as bad (it contains the bug!) hg bisect --reset hg bisect --bad Go back to a point where you think the bug isn't present hg update -r -200 Now...

When we want to create an orderable class, normally we need to define the methods __eq()__, __lt__(), __le__(), __gt__() and __ge__(). The total_ordering decorator, applied to a class, permits the definition of __eq__() and only one between __lt__(), __le__(), __gt__() and __ge__(), and still allow...