On 01.01.2019 02:08, James McCoy wrote: > On Mon, Dec 31, 2018 at 12:07:23AM +0100, Branko Čibej wrote: >> Summary: I propose to create one or possibly several new public header >> files that will be used by both the C and C++ public APIs. >> >> >> I would like to completely hide the dependency on APR from the public >> parts of the C++ API. In order to do that, public C++ headers must not >> include the C headers directly, because most if not all of them do >> expose APR. >> >> Up to now I've been "solving" this in an unsatisfactory and error-prone >> way, redefining enumeration values in C++ to be the same as in C, >> forward-declaring C structures in C++ headers, and so on. Instead, I'd >> like to extract certain parts of the C public API into a new header that >> is independent of APR, and use that in both APIs. This way I won't avoid >> redefining enumerations, for example, but I can ensure that both the C >> and C++ APIs use the same enumeration constant values. >> >> I'm attaching a patch that shows an example of what I have in mind. >> >> Please raise your objections by next year. :) >> >> -- Brane >> Index: subversion/include/svn__impl__types.h >> =================================================================== >> --- subversion/include/svn__impl__types.h (nonexistent) >> +++ subversion/include/svn__impl__types.h (working copy) >> @@ -0,0 +1,95 @@ >> +/** >> + * @copyright >> + * ==================================================================== >> + * Licensed to the Apache Software Foundation (ASF) under one >> + * or more contributor license agreements. See the NOTICE file >> + * distributed with this work for additional information >> + * regarding copyright ownership. The ASF licenses this file >> + * to you under the Apache License, Version 2.0 (the >> + * "License"); you may not use this file except in compliance >> + * with the License. You may obtain a copy of the License at >> + * >> + * http://www.apache.org/licenses/LICENSE-2.0 >> + * >> + * Unless required by applicable law or agreed to in writing, >> + * software distributed under the License is distributed on an >> + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY >> + * KIND, either express or implied. See the License for the >> + * specific language governing permissions and limitations >> + * under the License. >> + * ==================================================================== >> + * @endcopyright >> + * >> + * @file svn_types.h >> + * @brief Types implementation. >> + * This is a @b private implementation-specific header file. >> + * User code should not include it directly. >> + */ >> + >> +#ifndef SVN_X_IMPL_X_TYPES_H >> +#define SVN_X_IMPL_X_TYPES_H >> + >> +/* >> + * Define Subversion types that do not depend on APR or other >> + * external libraries (except for the C standard libvrary) and are >> + * shared betwen the C and C++ APIs. Do not include any headers >> + * except for the C standard library headers here. >> + */ >> + >> +#ifdef __cplusplus >> +extern "C" { >> +#endif /* __cplusplus */ >> + >> +/* Tristate values >> + * See: svn_tristate_t in svn_types.h >> + * tristate in svnxx/tristate.hpp >> + */ >> +enum svn__impl__tristate_t > In C++, identifiers with a double underscore _anywhere_ are reserved. > Although it's unlikely that these names will end up being used by a > compiler implementation somewhere, we probably shouldn't be using them.
True, I'd forgotten about that. I'm too used to breaking that rule in SVN's private/public APIs. :) -- Brane
