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Hochhaus, Andrew

21 Mar 2011 21 Mar '11

11:13 p.m.

Hi, I would like to use boost with BOOST_NO_EXCEPTIONS [1] and the g++ -fno-exceptions flag. However, it appears that some spots in boost library code: a) throw exceptions with the "raw" throw keyword [instead of BOOST_THROW_EXCEPTION or boost::throw_exception] b) use try ... catch blocks without "#ifnef BOOST_NO_EXCEPTIONS" guards This leaves me with the following questions. 1) Is BOOST_NO_EXCEPTIONS actively supported or a legacy construct? 2) What is the "recommended" way to throw exceptions inside boost library code (BOOST_THROW_EXCEPTION, boost::throw_exception, etc)? 3) If this is not intended behavior, would incremental patches to remove these dependencies be considered for inclusion? Thanks, Andy [1] http://www.boost.org/doc/libs/1_46_1/libs/exception/doc/throw_exception.html

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Emil Dotchevski

22 Mar 22 Mar

12:01 a.m.

On Mon, Mar 21, 2011 at 4:13 PM, Hochhaus, Andrew wrote:

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Hi,

I would like to use boost with BOOST_NO_EXCEPTIONS [1] and the g++ -fno-exceptions flag. However, it appears that some spots in boost library code:

a) throw exceptions with the "raw" throw keyword [instead of BOOST_THROW_EXCEPTION or boost::throw_exception] b) use try ... catch blocks without "#ifnef BOOST_NO_EXCEPTIONS" guards

This leaves me with the following questions.

1) Is BOOST_NO_EXCEPTIONS actively supported or a legacy construct?

It is actively supported.

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2) What is the "recommended" way to throw exceptions inside boost library code (BOOST_THROW_EXCEPTION, boost::throw_exception, etc)?

For BOOST_NO_EXCEPTIONS to work, it is sufficient to use boost::throw_exception to throw. However, it is recommended to use BOOST_THROW_EXCEPTION instead, which has the benefit of storing the file and line number into the exception object. See http://www.boost.org/doc/libs/release/libs/exception/doc/BOOST_THROW_EXCEPTI....

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3) If this is not intended behavior, would incremental patches to remove these dependencies be considered for inclusion?

You mean dependencies on boost/throw_exception.hpp? I'd think that patches that convert naked throws to BOOST_THROW_EXCEPTION should be accepted, since the boost/throw_exception.hpp header is extremely lightweight. Emil Dotchevski Reverge Studios, Inc. http://www.revergestudios.com/reblog/index.php?n=ReCode

Hochhaus, Andrew

30 Mar 30 Mar

10:16 p.m.

Thanks Emil. On Mon, Mar 21, 2011 at 7:01 PM, Emil Dotchevski wrote:

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2) What is the "recommended" way to throw exceptions inside boost library code (BOOST_THROW_EXCEPTION, boost::throw_exception, etc)?

For BOOST_NO_EXCEPTIONS to work, it is sufficient to use boost::throw_exception to throw. However, it is recommended to use BOOST_THROW_EXCEPTION instead, which has the benefit of storing the file and line number into the exception object. See http://www.boost.org/doc/libs/release/libs/exception/doc/BOOST_THROW_EXCEPTI....

That is what I was hoping for.

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3) If this is not intended behavior, would incremental patches to remove these dependencies be considered for inclusion?

You mean dependencies on boost/throw_exception.hpp? I'd think that patches that convert naked throws to BOOST_THROW_EXCEPTION should be accepted, since the boost/throw_exception.hpp header is extremely lightweight.

Yes. I'm hoping to convert naked throws to BOOST_THROW_EXCEPTION. While I'm at it, any reason why naked {try,catch} shouldn't also be converted to BOOST_{TRY,CATCH,CATCH_END}? boost/detail/no_exceptions_support.hpp -Andy

Emil Dotchevski

10:41 p.m.

On Wed, Mar 30, 2011 at 3:16 PM, Hochhaus, Andrew wrote:

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Thanks Emil.

On Mon, Mar 21, 2011 at 7:01 PM, Emil Dotchevski wrote:

...
...
2) What is the "recommended" way to throw exceptions inside boost library code (BOOST_THROW_EXCEPTION, boost::throw_exception, etc)?

For BOOST_NO_EXCEPTIONS to work, it is sufficient to use boost::throw_exception to throw. However, it is recommended to use BOOST_THROW_EXCEPTION instead, which has the benefit of storing the file and line number into the exception object. See http://www.boost.org/doc/libs/release/libs/exception/doc/BOOST_THROW_EXCEPTI....

That is what I was hoping for.

...
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3) If this is not intended behavior, would incremental patches to remove these dependencies be considered for inclusion?

You mean dependencies on boost/throw_exception.hpp? I'd think that patches that convert naked throws to BOOST_THROW_EXCEPTION should be accepted, since the boost/throw_exception.hpp header is extremely lightweight.

Yes. I'm hoping to convert naked throws to BOOST_THROW_EXCEPTION.

While I'm at it, any reason why naked {try,catch} shouldn't also be converted to BOOST_{TRY,CATCH,CATCH_END}?

Yes. See the long discussion we had about that issue. :) My personal opinion is that all throws in Boost should use BOOST_THROW_EXCEPTION, because otherwise we're taking away functionality that might be critical for some users of a library. Beyond that, I don't think we should be converting try...catch uses blindly. Emil Dotchevski Reverge Studios, Inc. http://www.revergestudios.com/reblog/index.php?n=ReCode

Vicente BOTET

10:59 p.m.

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Message du 31/03/11 00:42 De : "Emil Dotchevski" A : "Hochhaus, Andrew" Copie à : boost-users@lists.boost.org Objet : Re: [Boost-users] no exceptions

On Wed, Mar 30, 2011 at 3:16 PM, Hochhaus, Andrew wrote:

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Thanks Emil.

On Mon, Mar 21, 2011 at 7:01 PM, Emil Dotchevski wrote:

...
...
2) What is the "recommended" way to throw exceptions inside boost library code (BOOST_THROW_EXCEPTION, boost::throw_exception, etc)?

For BOOST_NO_EXCEPTIONS to work, it is sufficient to use boost::throw_exception to throw. However, it is recommended to use BOOST_THROW_EXCEPTION instead, which has the benefit of storing the file and line number into the exception object. See http://www.boost.org/doc/libs/release/libs/exception/doc/BOOST_THROW_EXCEPTI....

That is what I was hoping for.

Unfortunately there is no recommended way to work without no exceptions, as the long thread Emil mentioned explains. At least it is not included in the guidelines.

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3) If this is not intended behavior, would incremental patches to remove these dependencies be considered for inclusion?

You mean dependencies on boost/throw_exception.hpp? I'd think that patches that convert naked throws to BOOST_THROW_EXCEPTION should be accepted, since the boost/throw_exception.hpp header is extremely lightweight.

Yes. I'm hoping to convert naked throws to BOOST_THROW_EXCEPTION.

I'm sure that most of the library authors will accept the patch, but I will request directly before doing it.

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While I'm at it, any reason why naked {try,catch} shouldn't also be converted to BOOST_{TRY,CATCH,CATCH_END}?

There is alreadt boost/detail/no_exceptions_support.hpp void foo() { BOOST_TRY { ... } BOOST_CATCH(const std::bad_alloc&) { ... BOOST_RETHROW } BOOST_CATCH(const std::exception& e) { ... } BOOST_CATCH_END } With exception support enabled it will expand into: void foo() { { try { ... } catch (const std::bad_alloc&) { ... throw; } catch (const std::exception& e) { ... } } } With exception support disabled it will expand into: void foo() { { if(true) { ... } else if (false) { ... } else if (false) { ... } } }

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Yes. See the long discussion we had about that issue. :)

See the dev ML.

Hochhaus, Andrew

11:23 p.m.

Thanks for the guidance Emil and Vicente. On Wed, Mar 30, 2011 at 5:59 PM, Vicente BOTET wrote:

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While I'm at it, any reason why naked {try,catch} shouldn't also be converted to BOOST_{TRY,CATCH,CATCH_END}?

There is alreadt boost/detail/no_exceptions_support.hpp

Yes, these are the macros I was referring to.

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Yes. See the long discussion we had about that issue. :)

See the dev ML.

Will do. I believe this is the thread you are referencing: http://lists.boost.org/Archives/boost/2011/03/178982.php -Andy

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