选题[tech]: 20200722 The feature that makes D my favorite programming language

sources/tech/20200722 The feature that makes D my favorite programming language.md

sources/tech/20200722 The feature that makes D my favorite programming language.md

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+[#]: collector: (lujun9972)
+[#]: translator: ( )
+[#]: reviewer: ( )
+[#]: publisher: ( )
+[#]: url: ( )
+[#]: subject: (The feature that makes D my favorite programming language)
+[#]: via: (https://opensource.com/article/20/7/d-programming)
+[#]: author: (Lawrence Aberba https://opensource.com/users/aberba)
+
+The feature that makes D my favorite programming language
+======
+UFCS gives you the power to compose reusable code that has a natural
+flow without sacrificing convenience.
+![Coding on a computer][1]
+
+Back in 2017, I wrote about why the [D programming language is a great choice for development][2]. But there is one outstanding feature in D I didn't expand enough on: the [Universal Function Call Syntax][3] (UFCS). UFCS is a [syntactic sugar][4] in D that enables chaining any regular function on a type (string, number, boolean, etc.) like its member function of that type.
+
+If you don't already have D installed, [install a D compiler][5] so you can [run the D code][6] in this article yourself.
+
+Consider this example code:
+
+
+```
+// file: ufcs_demo.d
+
+module ufcs_demo;
+
+import std.stdio : writeln;
+
+int[] evenNumbers(int[] numbers)
+{
+    import std.array : array;
+    import std.algorithm : filter;
+
+    return numbers.filter!(n => n % 2 == 0).array;
+}
+
+void main()
+{
+    writeln(evenNumbers([1, 2, 3, 4]));
+}
+```
+
+Compile this with your favorite D compiler to see what this simple example application does:
+
+
+```
+$ dmd ufcs_demo.d
+$ ./ufcs_demo
+[2, 4]
+```
+
+But with UFCS as a built-in feature of D, you can also write your code in a natural way:
+
+
+```
+...
+writeln([1, 2, 3, 4].evenNumbers());
+...
+```
+
+or completely remove the now-redundant parenthesis to make it feel like `evenNumbers` is a property:
+
+
+```
+...
+writeln([1, 2, 3, 4].evenNumbers); // prints 2, 4
+...
+```
+
+So the complete code now becomes:
+
+
+```
+// file: ufcs_demo.d
+
+module ufcs_demo;
+
+import std.stdio : writeln;
+
+int[] evenNumbers(int[] numbers)
+{
+    import std.array : array;
+    import std.algorithm : filter;
+
+    return numbers.filter!(n => n % 2 == 0).array;
+}
+
+void main()
+{
+    writeln([1, 2, 3, 4].evenNumbers);
+}
+```
+
+Compile it with your favorite D compiler and try it out. As expected, it produces the same output:
+
+
+```
+$ dmd ufcs_demo.d
+$ ./ufcs_demo
+[2, 4]
+```
+
+During compilation, the compiler _automatically_ places the array as the first argument to the function. This is a regular pattern that makes using D such a joy, so it very much feels the same as you naturally think about your code. The result is functional-style programming.
+
+You can probably guess what this prints:
+
+
+```
+//file: cool.d
+import std.stdio : writeln;
+import std.uni : asLowerCase, asCapitalized;
+
+void main()
+{
+    string mySentence = "D IS COOL";
+    writeln(mySentence.asLowerCase.asCapitalized);
+}
+```
+
+But just to confirm:
+
+
+```
+$ dmd cool.d
+$ ./cool
+D is cool
+```
+
+Combined with [other D features][7], UFCS gives you the power to compose reusable code that has a natural flow to it without sacrificing convenience.
+
+### Time to try D
+
+As I've written before, D is a great language for development. It's easy to install from [the D download page][8], so download the compiler, take a look at the examples, and experience D for yourself.
+
+--------------------------------------------------------------------------------
+
+via: https://opensource.com/article/20/7/d-programming
+
+作者：[Lawrence Aberba][a]
+选题：[lujun9972][b]
+译者：[译者ID](https://github.com/译者ID)
+校对：[校对者ID](https://github.com/校对者ID)
+
+本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
+
+[a]: https://opensource.com/users/aberba
+[b]: https://github.com/lujun9972
+[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/code_computer_laptop_hack_work.png?itok=aSpcWkcl (Coding on a computer)
+[2]: https://opensource.com/article/17/5/d-open-source-software-development
+[3]: http://ddili.org/ders/d.en/ufcs.html
+[4]: https://en.wikipedia.org/wiki/Syntactic_sugar
+[5]: https://tour.dlang.org/tour/en/welcome/install-d-locally
+[6]: https://tour.dlang.org/tour/en/welcome/run-d-program-locally
+[7]: https://dlang.org/comparison.html
+[8]: https://dlang.org/download.html