🚀 go-pugleaf

In article s2p@stellar.comnet.com, Bret Pehrson <BretP@strata3d.com> writes:
>I have noticed that the new C++ standard library headers do 
>not include the traditional '.h' extension.
>
>Does anyone have any insight as to why this is?

Many early C++ implementations used a file extension other than ".h" for
header files. Choices included ".H", ".hpp", ".hxx", ".h++", and perhaps
others. Looking at this problem in 1991, the C++ committee concluded that
enshrining ".h" in the standard would be seen as discriminating against
many implementations.

It is the rule in Standard C that the names of the standard headers used
in angle brackets need not correspond to the name of any file. That is,
when you write <stdio.h>, there need not be any file in the system with
the name "stdio.h". The implementation is free to map the reserved
header name (in angle brackets) to anything -- it need not be a file
at all, for example, but instead the reserved header names could simply
enable declarations predefined inside the compiler. Or the implementation
could map <stdio.h> to a file called "asdfghjkl" if it wished.

The C++ committee decided in 1991 to make this point more obvious by
eliminating the ".h" from the C++ standard header names, thus
discriminating equally against all implementations. :-)  Now you write,
for example, <iostream>, and you might wind up getting a header file whose
name is iostream.h, iostream.H, iostream.hpp, iostream.hxx, iostream.h++,
or "zxcvbnm". (Or perhaps the implementation doesn't use actual files.)

For compatibility, I would expect implementations to continue to accept
the same spelling of standard headers that they always accepted. Thus,
if a compiler previous used <iostream.hxx>, I would expect it to continue
to accept <iostream.hxx>, and pick up the same header file as <iostream>.

---
Steve Clamage, stephen.clamage@eng.sun.com



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