UFCS is a key feature of D and enables code reusability and scalability through well-defined encapsulation.
UFCS allows any call to a free function
fun(a) to be written as a member function call a.fun().
If a.fun() is seen by the compiler and the type doesn't
have a member function called fun(), it tries to find a
global function whose first parameter matches that of a.
This feature is especially useful when chaining complex function calls. Instead of writing
foo(bar(a))
It is possible to write
a.bar().foo()
Moreover in D it is not necessary to use parentheses for functions without arguments, which means that any function can be used like a property:
import std.uni : toLower;
"D rocks".toLower; // "d rocks"
UFCS is especially important when dealing with ranges where several algorithms can be combined to perform complex operations, making it easier to write clear and manageable code.
import std.algorithm : group;
import std.range : chain, retro, front, dropOne;
[1, 2].chain([3, 4]).retro; // 4, 3, 2, 1
[1, 1, 2, 2, 2].group.dropOne.front; // tuple(2, 3u)
std.range