I have two entities payroll week and payroll period, want to write a query that checks if the start date and end date entered by the user to the payroll period table is found in the payroll week table which is populated already and update it with that payroll.
What select does is it returns all the objects for which the block returns a truthy value (i.e. Symfony / Doctrine - query date values against existing database values. Select is different than the ruby map method. But map is a more popular name for what it's doing than collect is. They are aliases for each other, so there is no difference. at (Option.scala:145) scala-library. This one tells me that the function fzfvimmaps autoload function (to. You can read more about using the each method here. The following is not a valid function because it does not start with a capital.
My guess is that your code fails when you try to initialize your own Main class that calls QtWidgets.QApplication init. And you use each to run the block over the elements without collecting the values. () requires at the very least a list of arguments to be passed to it when starting. You use map to collect the result of running the block over the elements of the array. It's actually a function object (or a functor), but that's just a side note.Īn example might make it easier to understand.map # => Map vs.
The result of evaluating the block is then used to construct the resulting array.Īpplying map on an array returns a new array where each element is the result of evaluating the block with the element as an argument.Īs you can see, the block plays the role of the function in Ruby. With map() functions, its not only easier, but its also much more flexible. Then, for each of the elements in the enumerable, it executes the block, passing it the current element as an argument. list(map(func, iterables)) The number of arguments to func must be. The main behaviour of this widget is to show an offline map made up from a bitmap that shows my location according to gps. The way the map method works in Ruby is, it takes an enumerable object, (i.e. in map mult 1.10 let functions with no arguments are actually constants and, once evaluated, will not evaluate again.
Higher-order functions are functions that accept a function as an argument and/or return a function as a return value. Here's the definition of higher-order functions. It means that Ruby has support for higher-order functions, and functional programming. I think it's so cool that the Ruby map method exists.