| Topic: |
DEVELOP > c-Plus-Plus |
| User: |
"ma740988" |
| Date: |
04 Jan 2008 10:08:02 PM |
| Object: |
Precompiled Header(s) |
Section 6.5 of Josuttis, C++ Templates states - and I paraphrase.
"Let's assume for the sake of argument that every file to be compiled
starts with the same N lines of code. We could compile these N lines
and save the complete state of the compiler at that point in a so-
called precompiled header. Then, for every file in our program, we
could reload the saved state and start compilation at line N+1."
Josuttis, went on to state that "In practice this measn the files must
start with the same #include directives, which consume a substantial
portion of our build time".
So given a file called 'std.hpp'. For discussion purposes assume
std.hpp contains the following.
# include <iostream>
# include <string>
# include <vector>
# include <deque>
# include <list>
Later: foo.cpp
# include "std.hpp"
template < typename T >
void confused ( const std::vector < T >& bogus ) {
// stuff
} // end confused
At issue: How can I 'save the complete state of the compiler" such
that any / all changes made to confused wont result in re-compilation
of std.hpp?
.
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| User: "Ivan Vecerina" |
|
| Title: Re: Precompiled Header(s) |
05 Jan 2008 02:48:39 AM |
|
|
"ma740988" <ma740988@gmail.com> wrote in message
news:0e71d277-bfa9-41bb-a8c0-17460d6c2724@i7g2000prf.googlegroups.com...
:
: Section 6.5 of Josuttis, C++ Templates states - and I paraphrase.
:
:
: "Let's assume for the sake of argument that every file to be compiled
: starts with the same N lines of code. We could compile these N lines
: and save the complete state of the compiler at that point in a so-
: called precompiled header. Then, for every file in our program, we
: could reload the saved state and start compilation at line N+1."
....
: At issue: How can I 'save the complete state of the compiler" such
: that any / all changes made to confused wont result in re-compilation
: of std.hpp?
Some compilers just happen to implement a precompiled headers feature,
which may be configured/implemented in various ways.
The complier may for example allow you to specify a special compilation
flag for some files that will trigger the generation of precompiled
header data. Other files, with a different compilation flag, are
then configured to use and load a precompiled header information.
This is all compiler-specific. For more specific information, please
check your compiler's documentation, or ask in a forum dedicated
to the compiler/platform you use.
Ivan
--
http://ivan.vecerina.com/contact/?subject=NG_POST <- email contact form
Brainbench MVP for C++ <> http://www.brainbench.com
.
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