Tutorial by Examples: n

The following example sets a promise to be consumed by another thread: { auto promise = std::promise<std::string>(); auto producer = std::thread([&] { promise.set_value("Hello World"); }); auto fut...

This code implements a version of std::async, but it behaves as if async were always called with the deferred launch policy. This function also does not have async's special future behavior; the returned future can be destroyed without ever acquiring its value. template<typename F> auto asyn...

std::packaged_task bundles a function and the associated promise for its return type: template<typename F> auto async_deferred(F&& func) -> std::future<decltype(func())> { auto task = std::packaged_task<decltype(func())()>(std::forward<F>(func)); aut...

# install sbt with homebrew (if you didn't) brew install sbt # - create a new scala project # - name your project name when asked like: hello-world sbt new sbt/scala-seed.g8 # go to the new project directory that you named cd hello-world # run sbt to open the sbt shell sbt # run you...

In general, there are two types of Bash scripts: System tools which operate from the current working directory Project tools which modify files relative to their own place in the files system For the second type of scripts, it is useful to change to the directory where the script is stored. T...

Such a group is made of radiobuttons that share a control variable so that no more than one can be selected. # control variable var = tk.IntVar(parent, 0) # group of radiobuttons for i in range(1,4): tk.Radiobutton(parent, text='Choice %i' % i, value=i, variable=var).pack() tk.Button(p...

Yank all lines containing TODO into a register by using append operation :global/TODO/yank A Here, we are searching for a TODO keyword globally, yanking all lines into register a (A register appends all lines to a register). NOTE: It is in general a good practice to clear a register before perf...

If constraints for std::promise and std::future are not met an exception of type std::future_error is thrown. The error code member in the exception is of type std::future_errc and values are as below, along with some test cases: enum class future_errc { broken_promise = /* the t...

How can I print hello world 5 times? 5.times{ println "hello world" }

Getting a GA Account: If you don’t have an Analytics account, create one. If you do have an Analytics account, sign in. Both options are available at google.com/analytics Setting up a property in your Analytics account: A property represents your website or app where the data gets aggrega...

The gross majority of the time a SyntaxError which points to an uninteresting line means there is an issue on the line before it (in this example, it's a missing parenthesis): def my_print(): x = (1 + 1 print(x) Returns File "<input>", line 3 print(x) ^...

To complete this objective following tasks are required. Foreach Loop Container: To iterate over a user configured directory for files. Expression Task: To update a variable if file exists. Steps First goto Solution Explorer double click on Project.params and create a parameter FolderPat...

The below coordinator job will trigger coordinator action once in a day that executes a workflow. The workflow has a shell script that moves input to output. <coordinator-app name="log_process_coordinator" frequency="${coord:days(1)}" start="2017-04-29T06:00Z" ...

Copy the script, coordinator.xml and workflow.xml into HDFS. coordinator.xml must be present in the directory specified by oozie.coord.application.path in job.properties. workflow.xml should be present in the directory specified by workflowAppUri. Once everything is in place, run the below command f...

Table/Column Names Two common ways of formatting table/column names are CamelCase and snake_case: SELECT FirstName, LastName FROM Employees WHERE Salary > 500; SELECT first_name, last_name FROM employees WHERE salary > 500; Names should describe what is stored in their object. Th...

There is no widely accepted standard. What everyone agrees on is that squeezing everything into a single line is bad: SELECT d.Name, COUNT(*) AS Employees FROM Departments AS d JOIN Employees AS e ON d.ID = e.DepartmentID WHERE d.Name != 'HR' HAVING COUNT(*) > 10 ORDER BY COUNT(*) DESC; At th...

Explicit joins should always be used; implicit joins have several problems: The join condition is somewhere in the WHERE clause, mixed up with any other filter conditions. This makes it harder to see which tables are joined, and how. Due to the above, there is a higher risk of mistakes, an...

Content of file.json (one JSON object per line): {"A": 1, "B": 2} {"A": 3, "B": 4} How to read directly from a local file: pd.read_json('file.json', lines=True) # Output: # A B # 0 1 2 # 1 3 4

Creating Express Web Server Express server came handy and it deeps through many user and community. It is getting popular. Lets create a Express Server. For Package Management and Flexibility for Dependency We will use NPM(Node Package Manager). Go to the Project directory and create package....

if len(sys.argv) != 4: # The script name needs to be accounted for as well. raise RuntimeError("expected 3 command line arguments") f = open(sys.argv[1], 'rb') # Use first command line argument. start_line = int(sys.argv[2]) # All arguments come as strings, so need to ...