Tutorial by Examples: ar

You can set an environment variable called PYTHONSTARTUP for Python's console. Whenever you enter the Python console, this file will be executed, allowing for you to add extra functionality to the console such as importing commonly-used modules automatically. If the PYTHONSTARTUP variable was set t...
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 ...
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...
In Prolog, custom operators can be defined using op/3: op(+Precedence, +Type, :Operator) Declares Operator to be an operator of a Type with a Precedence. Operator can also be a list of names in which case all elements of the list are declared to be identical operators. Precedence is an in...
Introduce environment variable VAGRANT_DEFAULT_PROVIDER export VAGRANT_DEFAULT_PROVIDER=vmware_fusion
vagrant up --provider vmware_fusion
vagrant up --provider vmware_workstation
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:...
When you pass an argument to a function, and the argument is a prvalue expression of the function's parameter type, and this type is not a reference, then the prvalue's construction can be elided. void func(std::string str) { ... } func(std::string("foo")); This says to create a tem...
The partial function creates partial function application from another function. It is used to bind values to some of the function's arguments (or keyword arguments) and produce a callable without the already defined arguments. >>> from functools import partial >>> unhex = partia...
/// <summary> /// Gets a BackgroundTask by its name /// </summary> /// <param name="taskName">Name of the task to find</param> /// <returns>The found Task or null if none found</returns> public BackgroundTaskRegistration TaskByName(string taskName) ...
Lubridate provides ymd() series of functions for parsing character strings into dates. The letters y, m, and d correspond to the year, month, and day elements of a date-time. mdy("07-21-2016") # Returns Date ## [1] "2016-07-21" mdy("07-21-2016", t...
This option allows you to clear a TLA for references and values at TLA allocation time and pre-fetch the next chunk. When an integer, a reference, or anything else is declared, it has a default value of 0 or null (depending upon type). At the appropriate time, you will need to clear these references...
When used with -XXallocClearChunkSize, this option sets the size of the chunks to be cleared. If this flag is used but no value is specified, the default is 512 bytes. Usage: -XXallocClearChunks -XXallocClearChunkSize=<size>[k|K][m|M][g|G]
By default, the navigation pattern works like a stack of pages, calling the newest pages over the previous pages. You will need to use the NavigationPage object for this. Pushing new pages ... public class App : Application { public App() { MainPage = new NavigationPage(new ...
After you've created and registered your platform-specific classes you can start hooking them up to your shared code. The following page contains a button that triggers the text-to-speech functionality using a pre-defined sentence. It uses DependencyService to retrieve a platform-specific implementa...

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