2.5. Alternatives to Wrapper #ifndef

2.5 Alternatives to Wrapper #ifndef

CPP supports two more ways of indicating that a header file should be read only once. Neither one is as portable as a wrapper ‘#ifndef’ and we recommend you do not use them in new programs, with the caveat that ‘#import’ is standard practice in Objective-C.

CPP supports a variant of ‘#include’ called ‘#import’ which includes a file, but does so at most once. If you use ‘#import’ instead of ‘#include’, then you don't need the conditionals inside the header file to prevent multiple inclusion of the contents. ‘#import’ is standard in Objective-C, but is considered a deprecated extension in C and C++.

‘#import’ is not a well designed feature. It requires the users of a header file to know that it should only be included once. It is much bet