tailieunhanh - D Programming Language PHẦN 3

"Có vẻ như với tôi rằng hầu hết các ngôn ngữ lập trình mới" rơi vào một trong hai loại: Những người từ giới học viện với mô hình mới triệt để và những người từ các tập đoàn lớn với một tập trung vào RAD và trang web Có lẽ thời gian của mình cho một ngôn ngữ mới sinh ra. | The D Programming Language class Foo2 Foo override int bar char c error no bar char in Foo int abc int x ok Static Attribute static The static attribute applies to functions and data. It means that the declaration does not apply to a particular instance of an object but to the type of the object. In other words it means there is no this reference. class Foo static int bar return 6 int foobar return 7 Foo f produces 6 error no instance of Foo produces 6 produces 7 Static functions are never virtual. Static data has only one instance for the entire program not once per object. Static does not have the additional C meaning of being local to a file. Use the private attribute in D to achieve that. For example module foo int x 3 x is global private int y 4 y is local to module foo Static can be applied to constructors and destructors producing static constructors and static destructors. Auto Attribute auto The auto attribute is used for local variables and for class declarations. For class declarations the auto attribute creates an auto class. For local declarations auto implements the RAII Resource Acquisition Is Initialization protocol. This means that the destructor for an object is automatically called when the auto reference to it goes out of scope. The destructor is called even if the scope is exited via a thrown exception thus auto is used to guarantee cleanup. Auto cannot be applied to globals statics data members inout or out parameters. Arrays of autos are not allowed and auto function return values are not allowed. Assignment to an auto 47 The D Programming Language other than initialization is not allowed. Rationale These restrictions may get relaxed in the future if a compelling reason to appears. 48 The D Programming Language Expressions C and C programmers will find the D expressions very familiar with a few interesting additions. Expressions are used to compute values with a resulting type. These values can then be .