问题
So I wanted to separate out just the smart pointers from boost to use in my project and I was guided to use bcp utility.
Today I got it compiled and did bcp smart_ptr to_copy_to_my_project/.
The result: 6MB of code in to_copy_to_my_project/ directory.
Are you kidding me? I don't want to add 6MB of header files to my 100KB project just to use smart pointers.
For example, it copies the following win32 stuff (I am on Linux):
Copying file: boost/thread/win32/basic_timed_mutex.hpp
Copying file: boost/thread/win32/condition_variable.hpp
Copying file: boost/thread/win32/interlocked_read.hpp
Why would it copy win32 stuff with smart_ptr when I am on Linux?
Also:
Copying file: boost/mpl/aux_/preprocessed/msvc60/advance_backward.hpp
...
Copying file: boost/mpl/aux_/preprocessed/msvc70/advance_backward.hpp
...
Copying file: boost/mpl/aux_/preprocessed/mwcw/advance_backward.hpp
And:
Copying file: boost/date_time/adjust_functors.hpp
Why does smart_ptr depend on date_time?
Also what about all these tests that it copied over:
Copying file: libs/smart_ptr/test/allocate_shared_esft_test.cpp
...
I don't need any of it! I just need smart_ptr!
Did I do something wrong? Why did it copy 6MB of code just for the smart pointers, which I would expect to be 10KB or 20KB...
Thanks, Boda Cydo.
回答1:
If all you want is smart_ptr and you're not interested in #define'ing BOOST_SP_USE_QUICK_ALLOCATOR (which is not defined by default), you only need:
boost/assert.hpp
boost/checked_delete.hpp
boost/config.hpp
boost/config/compiler/*
boost/config/no_tr1/functional.hpp
boost/config/no_tr1/memory.hpp
boost/config/no_tr1/utility.hpp
boost/config/platform/*
boost/config/posix_features.hpp
boost/config/select_compiler_config.hpp
boost/config/select_platform_config.hpp
boost/config/select_stdlib_config.hpp
boost/config/stdlib/*
boost/config/suffix.hpp
boost/config/user.hpp
boost/current_function.hpp
boost/detail/interlocked.hpp
boost/detail/sp_typeinfo.hpp
boost/detail/workaround.hpp
boost/enable_shared_from_this.hpp
boost/exception/detail/attribute_noreturn.hpp
boost/exception/exception.hpp
boost/memory_order.hpp
boost/non_type.hpp
boost/shared_ptr.hpp
boost/smart_ptr/*
boost/throw_exception.hpp
boost/type.hpp
This comes to 365k, with the bulk of the code actually in boost/smart_ptr. There is still a lot of code in boost/config. If you know what platforms you're targeting, you could pare down boost/config/compiler, boost/config/platform, and boost/config/stdlib. Then the vast majority of the code would be in boost/smart_ptr.
回答2:
You could just use the stl's shared pointer: std::tr1::shared_ptr, which for all intents and purposes "is" boost::shared_ptr.
回答3:
I suspect that you could delete the test and win32 folders--they are probably only included when testing or on that platform. I can't speak to most of the header files, but I know smart_ptr does lots of crazy stuff so that you can convert boost::shared_ptr<Foo> into boost::shared_ptr<const Foo>, which most templates can't do. If you'd like a counting pointer that fits in only a few files, it's not hard to write one, but it won't be as nice as boost.
Since you say you're on Linux, why not just list boost as a dependency?
回答4:
The reason being that boost supports a myriad platforms and compilers and boost modules uses other boost modules liberally. Even though most of it will be #ifdef:ed away bcp isn't smart enough to do that.
I had a similar issue so I understand your concern. I tried running the preprocessor with out platform settings then the code became significantly smaller.
In the end though we upgraded the compiler to the version that supports C++ tr1 and use std::tr1::shared_ptr.
One might argue that 6Megs are a small price to pay for industry standard smart pointers however not all developers/architects feel the same way and since I'm no despot yet I had to go with what the team decides.
回答5:
bcp will copy a lot less if you do
bcp shared_ptr.hpp to_copy_to_my_project/.
It still seems like way too much, I agree.
来源：https://stackoverflow.com/questions/3484585/why-did-boosts-bcp-smart-ptr-dir-copy-6mb-of-source-code