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diff --git a/doxygen/dox/api-compat-macros.dox b/doxygen/dox/api-compat-macros.dox new file mode 100644 index 0000000..6b85ccb --- /dev/null +++ b/doxygen/dox/api-compat-macros.dox @@ -0,0 +1,899 @@ +/** \page api-compat-macros API Compatibility Macros + \tableofcontents + + \section audience Audience + The target audience for this document has existing applications that use the + HDF5 library, and is considering moving to the latest HDF5 release to take + advantage of the latest library features and enhancements. + + \section compat-issues Compatibility Issues + With each major release of HDF5, such as 1.12 or 1.10, certain compatibility + issues must be considered when migrating applications from an earlier major + release. + + This document describes the approach taken by The HDF Group to help existing + users of HDF5 address compatibility issues in the HDF5 API. + + \section summary Summary and Motivation + In response to new and evolving requirements for the library and data format, + several basic functions have changed since HDF5 was first released. To allow + existing applications to continue to compile and run properly, all versions + of these functions have been retained in the later releases of the HDF5 library. + + Given the scope of changes available with each major release of HDF5, and + recognizing the potentially time-consuming task of editing all the affected + calls in user applications, The HDF Group has created a set of macros that + can be used to flexibly and easily map existing API calls to previous release + functions. We refer to these as the \Emph{API compatibility macros}. + + The HDF Group generally encourages users to update applications to work with + the latest HDF5 library release so that all new features and enhancements are + available to them. At the same time, The HDF Group understands that, under + some circumstances, updating applications may not be feasible or necessary. + The API compatibility macros, described in this document, provide a bridge + from old APIs to new and can be particularly helpful in situations such as these: + <ul> + <li>Source code is not available - only binaries are available; updating the + application is not feasible.</li> + <li>Source code is available, but there are no resources to update it.</li> + <li>Source code is available, as are resources to update it, but the old + version works quite well so updates are not a priority. At the same time, + it is desirable to take advantage of certain efficiencies in the newer HDF5 + release that do not require code changes.</li> + <li>Source code is available, as are resources to update it, but the applications + are large or complex, and must continue to run while the code updates are + carried out.</li> + </ul> + + \section using Understanding and Using the Macros + As part of latest HDF5 release, several functions that existed in previous + versions of the library were updated with new calling parameters and given + new names. The updated versions of the functions have a number (for, e.g., '2') + at the end of the original function name. The original versions of these + functions were retained and renamed to have an earlier number (for, e.g., '1') + at the end of the original function name. + + For example, consider the function \Code{H5Lvisit} in HDF5 release 1.10 + as compared with 1.12: + + <table> + <tr> + <th>Original function name and signature in 1.10.0</th> + <td colspan="1"> + \Code{herr_t H5Lvisit(hid_t grp_id, H5_index_t idx_type, H5_iter_order_t order, H5L_iterate_t op, void *op_data)} + </td> + </tr> + <tr> + <th>Updated function and signature, introduced in release 1.12.0</th> + <td colspan="1"> + \Code{herr_t H5Lvisit2(hid_t group_id, H5_index_t idx_type, H5_iter_order_t order, H5L_iterate2_t op, void *op_data)} + </td> + </tr> + <tr><th>Original function and signature, renamed in release 1.12.0</th> + <td colspan="1"> + \Code{herr_t H5Lvisit1(hid_t group_id, H5_index_t idx_type, H5_iter_order_t order, H5L_iterate1_t op, void *op_data)} + </td> + </tr> + <tr><th>API compatibility macro, introduced in release 1.12.0</th> + <td colspan="1"> + \Code{H5Lvisit} + <p>The macro, \Code{H5Lvisit}, will be mapped to either \Code{H5Lvisit1} or + \Code{H5Lvisit2}. The mapping is determined by a combination of the + configuration options use to build the HDF5 library and compile-time + options used to build the application. The calling parameters used with the + \Code{H5Lvisit} compatibility macro should match the number and type of the + function the macros will be mapped to (\Code{H5Lvisit1} or \Code{H5Lvisit2}). + </p> + <p>The function names ending in '1' or '2' are referred to as \Emph{versioned names}, + and the corresponding functions are referred to as \Emph{versioned functions}. + For new code development, The HDF Group recommends use of the compatibility macro + mapped to the latest version of the function. The original version of the function + should be considered deprecated and, in general, should not be used when developing + new code. + </p> + </td> + </tr> + </table> + + \section options Compatibility Macro Mapping Options + To determine the mapping for a given API compatibility macro in a given application, + a combination of user-controlled selections, collectively referred to as the + \Emph{compatibility macro mapping options}, is considered in the following sequence: + + <table border="0" style="width: 100.0%;"> + <tr> + <td valign="top" width="50%"> + <ol> + <li>What compatibility macro configuration option was used to build the HDF5 library? + We refer to this selection as the \Emph{library mapping}.</li> + <li>Was a compatibility macro global compile-time option specified when the application + was built? We refer to this (optional) selection as the \Emph{application mapping}. + If an application mapping exists, it overrides the library mapping. + \Emph{(See adjacent notes.)}</li> + <li>Were any compatibility macro function-level compile-time options specified when the + application was built? We refer to these (optional) selections as \Emph{function mappings}. + If function mappings exist, they override library and application mappings for the + relevant API compatibility macros. \Emph{(See adjacent notes.)}</li> + </ol> + </td> + <td valign="top" width="50%"> + <table border="1" cellpadding="10" style="width: 100.0%;"> + <tr><td> + \Bold{Notes:} An application mapping can map APIs to the same version or to a version + older than the configured library mapping. When the application attempts to map APIs + to a newer version of the API than the library was configured with, it will fail to + "upgrade" the mapping (and may fail silently). + + When it is necessary to "upgrade" the macro mappings from those set in the library mapping, + it must be done at the per-function level, using the function-level mappings. As long as + one does not try to map a function to a version that was compiled out in the library mapping, + individual functions can be upgraded or downgraded freely. + </td> + </tr> + </table> + </td> + </tr> + </table> + + \subsection lib-options Library Mapping Options + When the HDF5 library is built, \Code{configure} flags can be used to control the API + compatibility macro mapping behavior exhibited by the library. This behavior can be + overridden by application and function mappings. One configure flag excludes deprecated + functions from the HDF5 library, making them unavailable to applications linked with the + library. + + <div align="center">Table 1: Library Mapping Options + <table border="1" cellpadding="3"> + <tr> + <th>\Code{configure} flag</th> + <th>Macros map to release <br/> (versioned function; \Code{H5Lvisit} shown)</th> + <th>Deprecated functions available? <br/> (\Code{H5Lvisit1})</th> + </tr> + <tr align="center"> + <td>\Code{--with-default-api-version=v112} <br/> (the default in 1.12)</td> + <td>1.12.x (\Code{H5Lvisit2})</td> + <td>yes</td> + </tr> + <tr align="center"> + <td align="left">\Code{--with-default-api-version=v110}</td> + <td>1.10.x (\Code{H5Lvisit1})</td> + <td>yes</td> + </tr> + <tr align="center"> + <td align="left">\Code{--with-default-api-version=v18}</td> + <td>1.8.x (\Code{H5Lvisit1})</td> + <td>yes</td> + </tr> + <tr align="center"> + <td align="left">\Code{--with-default-api-version=v16}</td> + <td>1.6.x (\Code{H5Lvisit1})</td> + <td>yes</td> + </tr> + <tr align="center"> + <td align="left">\Code{--disable-deprecated-symbols}</td> + <td>1.12.x (\Code{H5Lvisit2})</td> + <td>no</td> + </tr> + </table> + </div> + Refer to the file \Code{libhdf5.settings} in the directory where the HDF5 library is + installed to determine the \Code{configure} flags used to build the library. In particular, + look for the two lines shown here under \Emph{Features}: + + \Code{Default API mapping: v112} + + \Code{With deprecated public symbols: yes} + + \subsection app-options Application Mapping Options + When an application using HDF5 APIs is built and linked with the HDF5 library, + compile-time options to \Code{h5cc} can be used to control the API compatibility + macro mapping behavior exhibited by the application. The application mapping + overrides the behavior specified by the library mapping, and can be overridden + on a function-by-function basis by the function mappings. + + If the HDF5 library was configured with the \Code{--disable-deprecated-symbols} flag, then + the deprecated functions will not be available, regardless of the application mapping options. + + <div align="center">Table 2: Application Mapping Options + <table border="1" cellpadding="3"> + <tr> + <th>\Code{h5cc} option</th> + <th>Macros map to release <br/>(versioned function; \Code{H5Lvisit} shown)</th> + <th>Deprecated functions available? <br/>(\Code{H5Lvisit1})</th> + </tr> + <tr align="center"> + <td align="left">\Code{-DH5_USE_112_API} <br/> \Emph{(Default behavior if no option specified.)}</td> + <td>1.12.x (\Code{HLvisit2})</td> + <td>yes* <br/> \Emph{*if available in library}</td> + </tr> + <tr align="center"> + <td align="left">\Code{-DH5_USE_110_API}</td> + <td>1.10.x (\Code{HLvisit1})</td> + <td>yes* <br/> \Emph{*if available in library}</td> + </tr> + <tr align="center"> + <td align="left">\Code{-DH5_USE_18_API}</td> + <td>1.8.x (\Code{H5Lvisit1})</td> + <td>yes* <br/> \Emph{*if available in library}</td> + </tr> + <tr align="center"> + <td align="left">\Code{-DH5_USE_16_API}</td> + <td>1.6.x (\Code{H5Lvisit1})</td> + <td>yes* <br/> \Emph{*if available in library}</td> + </tr> + <tr align="center"> + <td align="left">\Code{-DH5_NO_DEPRECATED_SYMBOLS}</td> + <td>1.10.x (\Code{H5Lvisit1})</td> + <td>no</td> + </tr> + </table> + </div> + + \subsection fun-options Function Mapping Options + Function mappings are specified when the application is built. These mappings + can be used to control the mapping of the API compatibility macros to + underlying functions on a function-by-function basis. The function mappings + override the library and application mappings discussed earlier. + + If the HDF5 library was configured with the \Code{--disable-deprecated-symbols} + flag, or \Code{-DH5_NO_DEPRECATED_SYMBOLS} is used to compile the application, + then the deprecated functions will not be available, regardless of the function + mapping options. + + For every function with multiple available versions, a compile-time version flag + can be defined to selectively map the function macro to the desired versioned + function. The function mapping consists of the function name followed by + "\Code{_vers}" which is mapped by number to a specific function or + struct: + <table> + <tr> + <th>Macro</th> + <th>Function Mapping</th> + <th>Mapped to function or struct</th> + </tr> + <tr><td>\Code{H5xxx}</td> + <td>\Code{H5xxx_vers=1}</td> + <td>\Code{H5xxx1}</td> + </tr> + <tr> + <td> </td> + <td>\Code{H5xxx_vers=2}</td> + <td>\Code{H5xxx2}</td> + </tr> + </table> + + For example, in version 1.10 the \Code{H5Rreference} macro can be mapped to + either \Code{H5Rreference1} or \Code{H5Rreference2}. When used, the value of + the \Code{H5Rreference_vers} compile-time version flag determines which + function will be called: + + <ul> + <li>When \Code{H5Rreference_vers} is set to \Code{1}, the macro \Code{H5Rreference} + will be mapped to \Code{H5Rreference1}. <br/> + \Code{H5cc ... -DH5Rreference_vers=1 ...}</li> + <li>When \Code{H5Rdereference_vers} is set to \Code{2}, the macro \Code{H5Rdereference} + will be mapped to \Code{H5Rdereference2}. <br/> + \Code{h5cc ... -DH5Rreference_vers=2 ...}</li> + <li>When \Code{H5Rreference_vers} is not set, the macro \Code{H5Rreference} will be + mapped to either \Code{H5Rreference1} or \Code{H5Rreference2}, based on the + application mapping, if one was specified, or on the library mapping. <br/> + \Code{h5cc ... }</li> + </ul> + + \warning Please be aware that some function mappings use mapped structures, as + well. If compiling an application with a function mapping that uses + a mapped structure, you must include each function and mapped structure + plus EVERY function that uses the mapped structure, whether or not that + function is used in the application. \Emph{In 1.12, mappings of structures + are used by the H5L and H5O function mappings.}\n\n + For example, an application \Code{application.c} only calls \Code{H5Lvisit}, + \Code{H5Ovisit}, and \Code{H5Oget_info_by_name}. To compile this application + with 1.10 APIs in 1.12 with the function specific mappings, then not only must + \Code{H5Lvisit_vers}, \Code{H5Ovisit_vers}, and \Code{H5Oget_info_by_name_vers} + be specified on the command line, but the mapped structures and every + function that uses the mapped structures must be included, as well. + The full compile line is shown below: + \code{.sh} + h5cc -DH5Lvisit_vers=1 -DH5Ovisit_vers=1 -DH5Oget_info_by_name_vers=1 \ + -DH5Lvisit_by_name_vers=1 -DH5Literate_vers=1 \ + -DH5Literate_by_name_vers= -DH5O_info_t_vers=1 -DH5L_info_t_vers=1 \ + -DH5L_iterate_t_vers=1 -DH5Lget_info_by_idx_vers=1 \ + -DH5Lget_info_vers=1 application.c + \endcode + + \subsubsection fun-options-112 Function Mapping Options in Releases 1.12.x + <table> + <tr> + <th style="text-align: left;">Macro <br/> (\Code{H5xxx})</th> + <th>Default function used if no macro specified + <ul><li>Function/struct mapping:\Code{H5xxx_vers=N}</li></ul> + </th> + <th>Function used if specifying 1.10 + <ul><li>Function/struct mapping: \Code{H5xxx_vers=1}</li></ul> + </th> + </tr> + <tr> + <td>H5Lget_info()</td> + <td>H5Lget_info2() + <ul> + <li>Function mapping:\Code{H5Lget_info_vers=2}</li> + <li>Struct mapping:\Code{H5L_info_t_vers=2}</li> + </ul> + </td> + <td>H5Lget_info1() + <ul> + <li>Function mapping \Code{H5Lget_info_vers=1}</li> + <li>Struct mapping: \Code{H5L_info_t_vers=1}</li> + </ul> + </td> + </tr> + <tr> + <td>H5Lget_info_by_idx()</td> + <td>H5Lget_info_by_idx2() + <ul> + <li>Function mapping: \Code{H5Lget_info_by_idx_vers=2}</li> + <li>Struct mapping: \Code{H5L_info_t_vers=2}</li> + </ul> + </td> + <td>H5Lget_info_by_idx1() + <ul> + <li>Function mapping: \Code{H5Lget_info_by_idx_vers=1}</li> + <li>Struct mapping: \Code{H5L_info_t_vers=1}</li> + </ul> + </td> + </tr> + <tr> + <td>H5Literate()</td> + <td>H5Literate2() + <ul> + <li>Function mapping: \Code{H5Literate_vers=2}</li> + <li>Struct mapping: \Code{H5L_iterate_t_vers=2}</li> + </ul> + </td> + <td>H5Literate1() + <ul> + <li>Function mapping: \Code{H5Literate_vers=1}</li> + <li>Struct mapping: \Code{H5L_iterate_t_vers=1}</li> + </ul> + </td> + </tr> + <tr> + <td>H5Literate_by_name()</td> + <td>H5Literate_by_name2() + <ul> + <li>Function mapping: \Code{H5Literate_by_name_vers=2}</li> + <li>Struct mapping: \Code{H5L_iterate_t_vers=2}</li> + </ul> + </td> + <td>H5Literate_by_name1() + <ul> + <li>Function mapping: \Code{H5Literate_by_name_vers=1}</li> + <li>Struct mapping: \Code{H5L_iterate_t_vers=1}</li> + </ul> + </td> + </tr> + <tr> + <td>H5Lvisit()</td> + <td>H5Lvisit2() + <ul> + <li>Function mapping: \Code{H5Lvisit_vers=2}</li> + <li>Struct mapping: \Code{H5L_iterate_t_vers=2}</li> + </ul> + </td> + <td>H5Lvisit1() + <ul> + <li>Function mapping: \Code{H5Lvisit_vers=1}</li> + <li>Struct mapping: \Code{H5L_iterate_t_vers=1}</li> + </ul> + </td> + </tr> + <tr> + <td>H5Lvisit_by_name()</td> + <td>H5Lvisit_by_name2() + <ul> + <li>Function mapping: \Code{H5Lvisit_by_name_vers=2}</li> + <li>Struct mapping: \Code{H5L_iterate_t_vers=2}</li> + </ul> + </td> + <td>H5Lvisit_by_name1() + <ul> + <li>Function mapping: \Code{H5Lvisit_by_name_vers=1}</li> + <li>Struct mapping: \Code{H5L_iterate_t_vers=1}</li> + </ul> + </td> + </tr> + <tr> + <td>H5Oget_info()</td> + <td>H5Oget_info3() + <ul> + <li>Function mapping: \Code{H5Oget_info_vers=3}</li> + <li>Struct mapping: \Code{H5O_info_t_vers=2}</li> + </ul> + </td> + <td>H5Oget_info1() + <ul> + <li>Function mapping: \Code{H5Oget_info_vers=1}</li> + <li>Struct mapping: \Code{H5O_info_t_vers=1}</li> + </ul> + </td> + </tr> + <tr> + <td>H5Oget_info_by_idx()</td> + <td>H5Oget_info_by_idx3() + <ul><li>Function mapping: \Code{H5Oget_info_by_idx_vers=3}</li> + <li>Struct mapping: \Code{H5O_info_t_vers=2}</li> + </ul> + </td> + <td>H5Oget_info_by_idx1() + <ul> + <li>Function mapping: \Code{H5Oget_info_by_idx_vers=1}</li> + <li>Struct mapping: \Code{H5O_info_t_vers=1}</li> + </ul> + </td> + </tr> + <tr> + <td>H5Oget_info_by_name()</td> + <td>H5Oget_info_by_name3() + <ul> + <li>Function mapping: \Code{H5O_get_info_by_name_vers=3}</li> + <li>Struct mapping: \Code{H5O_info_t_vers=2}</li> + </ul> + </td> + <td>H5Oget_info_by_name1() + <ul> + <li>Function mapping: \Code{H5O_get_info_by_name_vers=1}</li> + <li>Struct mapping: \Code{H5O_info_t_vers=1}</li> + </ul> + </td> + </tr> + <tr> + <td>H5Ovisit()</td> + <td>H5Ovisit3() + <ul> + <li>Function mapping: \Code{H5Ovisit_vers=3}</li> + <li>Struct mapping: \Code{H5O_iterate_t_vers=2}</li> + </ul> + </td> + <td>H5Ovisit1() + <ul><li>Function mapping: \Code{H5Ovisit_vers=1}</li> + <li>Struct mapping: \Code{H5O_iterate_t_vers=1}</li> + </ul> + </td> + </tr> + <tr> + <td>H5Ovisit_by_name()</td> + <td>H5Ovisit_by_name3() + <ul> + <li>Function mapping: \Code{H5Ovisit_by_name_vers=3}</li> + <li>Struct mapping: \Code{H5O_iterate_t_vers=2}</li> + </ul> + </td> + <td>H5Ovisit_by_name1() + <ul> + <li>Function mapping: \Code{H5Ovisit_by_name_vers=1}</li> + <li>Struct mapping: \Code{H5O_iterate_t_vers=1}</li> + </ul> + </td> + </tr> + <tr> + <td>H5Pencode()</td> + <td>H5Pencode2() + <ul> + <li>Function mapping: \Code{H5Pencode_vers=2}</li> + </ul> + </td> + <td>H5Pencode1() + <ul> + <li>Function mapping: \Code{H5Pencode_vers=1}</li> + </ul> + </td> + </tr> + <tr> + <td>H5Sencode()</td> + <td>H5Sencode2() + <ul> + <li>Function mapping: \Code{H5Sencode_vers=2}</li> + </ul> + </td> + <td>H5Sencode1() + <ul> + <li>Function mapping: \Code{H5Sencode_vers=1}</li> + </ul> + </td> + </tr> + </table> + + \subsubsection fun-options-110 Function Mapping Options in Releases 1.10.x + <table> + <tr> + <th>Macro</th> + <th>Default function used <br/> <sub>(if no macro specified)</sub></th> + <th>Introduced in</th> + <th>\Code{h5cc} version flag and value</th> + <th>Mapped to function or struct</th> + </tr> + <tr> + <td rowspan="2">H5Rdereference()</td> + <td rowspan="2">H5Rdereference2()</td> + <td rowspan="2">HDF5-1.10.0</td> + <td>\Code{-DH5Rdereference_vers=1}</td> + <td>H5Rdereference1()</td> + </tr> + <tr> + <td>\Code{-DH5Rdereference_vers=2}</td> + <td>H5Rdereference2()</td> + </tr> + <tr> + <td rowspan="2">H5Fget_info()</td> + <td rowspan="2">H5Fget_info2()</td> + <td rowspan="2">HDF5-1.10.0</td> + <td>\Code{-DH5Fget_info_vers=1}</td> + <td>H5Fget_info1() with struct \ref H5F_info1_t</td> + </tr> + <tr> + <td>\Code{-DH5Fget_info_vers=2}</td> + <td>H5Fget_info2() with struct \ref H5F_info2_t</td> + </tr> + <tr> + <td rowspan="2">H5Oget_info()</td> + <td rowspan="2">H5Oget_info1()</td> + <td rowspan="2">HDF5-1.10.3</td> + <td>\Code{-DH5Oget_info_vers=1}</td> + <td>H5Oget_info1()</td> + </tr> + <tr> + <td>\Code{-DH5Oget_info_vers=2}</td> + <td>H5Oget_info2()</td> + </tr> + <tr> + <td rowspan="2">H5Oget_info_by_idx()</td> + <td rowspan="2">H5Oget_info_by_idx1()</td> + <td rowspan="2">HDF5-1.10.3</td> + <td>\Code{-DH5Oget_info_by_idx_vers=1}</td> + <td>H5Oget_info_by_idx1()</td> + </tr> + <tr> + <td>\Code{-DH5Oget_info_by_idx_vers=2}</td> + <td>H5Oget_info_by_idx2()</td> + </tr> + <tr> + <td rowspan="2">H5Oget_info_by_name()</td> + <td rowspan="2">H5Oget_info_by_name1()</td> + <td rowspan="2">HDF5-1.10.3</td> + <td>\Code{-DH5Oget_info_by_name_vers=1}</td> + <td>H5Oget_info_by_name1()</td> + </tr> + <tr> + <td>\Code{-DH5Oget_info_by_name_vers=2}</td> + <td>H5Oget_info_by_name2()</td> + </tr> + <tr> + <td rowspan="2">H5Ovisit()</td> + <td rowspan="2">H5Ovisit1()</td> + <td rowspan="2">HDF5-1.10.3</td> + <td>\Code{-DH5Ovisit_vers=1}</td> + <td>H5Ovisit1()</td> + </tr> + <tr> + <td>\Code{-DH5Ovisit_vers=2}</td> + <td>H5Ovisit2()</td> + </tr> + <tr> + <td rowspan="2">H5Ovisit_by_name()</td> + <td rowspan="2">H5Ovisit_by_name1()</td> + <td rowspan="2">HDF5-1.10.3</td> + <td>\Code{-DH5Ovisit_by_name_vers=1}</td> + <td>H5Ovisit_by_name1()</td> + </tr> + <tr> + <td>\Code{-DH5Ovisit_by_name_vers=2}</td> + <td>H5Ovisit_by_name2()</td> + </tr> + </table> + + \subsubsection fun-options-18 Function Mapping Options in Releases 1.8.x + At release 1.8.0, the API compatibility macros, function mapping compile-time + version flags and values, and corresponding versioned functions listed in the + following table were introduced. If the application being compiled to run with + any 1.10.x release was written to use any 1.6.x release of HDF5, you must also + consider these macros and mapping options. + + <div align="center">Table 5: Function Mapping Options in Releases 1.8.x + <table border="1" cellpadding="3" style="width: 90.0%;"> + <tr> + <th>Macro</th> + <th><code>h5cc</code> version flag and value</th> + <th>Mapped to function <br/> or struct</th> + </tr> + <tr> + <td rowspan="2">H5Acreate()</td> + <td>\Code{DH5Acreate_vers=1}</td> + <td>H5Acreate1()</td> + </tr> + <tr> + <td>\Code{DH5Acreate_vers=2}</td> + <td>H5Acreate2()</td> + </tr> + <tr> + <td rowspan="2">H5Aiterate()</td> + <td>\Code{DH5Aiterate_vers=1}</td> + <td>H5Aiterate1() <br/> with struct \ref H5A_operator1_t</td> + </tr> + <tr> + <td>\Code{DH5Aiterate_vers=2}</td> + <td>H5Aiterate2() <br/> with struct \ref H5A_operator2_t</td> + </tr> + <tr> + <td rowspan="2">H5Dcreate()</td> + <td>\Code{DH5Dcreate_vers=1}</td> + <td>H5Dcreate1()</td> + </tr> + <tr> + <td>\Code{DH5Dcreate_vers=2}</td> + <td>H5Dcreate2()</td> + </tr> + <tr><td rowspan="2">H5Dopen()</td> + <td>\Code{DH5Dopen_vers=1}</td> + <td>H5Dopen1()</td> + </tr> + <tr> + <td>\Code{DH5Dopen_vers=2}</td> + <td>H5Dopen2()</td> + </tr> + <tr> + <td rowspan="2">H5Eclear()</td> + <td>\Code{DH5Eclear_vers=1}</td> + <td>H5Eclear1()</td> + </tr> + <tr> + <td>\Code{DH5Eclear_vers=2}</td> + <td>H5Eclear2()</td> + </tr> + <tr> + <td rowspan="2">H5Eprint()</td> + <td>\Code{DH5Eprint_vers=1}</td> + <td>H5Eprint1()</td> + </tr> + <tr> + <td>\Code{DH5Eprint_vers=2}</td> + <td>H5Eprint2()</td> + </tr> + <tr> + <td rowspan="2">H5Epush()</td> + <td>\Code{DH5Epush_vers=1}</td> + <td>H5Epush1()</td> + </tr> + <tr> + <td>\Code{DH5Epush_vers=2}</td> + <td>H5Epush2()</td> + </tr> + <tr> + <td rowspan="2">H5Eset_auto()</td> + <td>\Code{DH5Eset_auto_vers=1}</td> + <td>H5Eset_auto1()</td> + </tr> + <tr> + <td>\Code{DH5Eset_auto_vers=2}</td> + <td>H5Eset_auto2()</td> + </tr> + <tr> + <td rowspan="2">H5Eget_auto()</td> + <td>\Code{DH5Eget_auto_vers=1}</td> + <td>H5Eget_auto1()</td> + </tr> + <tr> + <td>\Code{DH5Eget_auto_vers=2}</td> + <td>H5Eget_auto2()</td> + </tr> + <tr> + <td rowspan="2">\ref H5E_auto_t <br/> struct for H5Eset_auto() <br/> and H5Eget_auto()</td> + <td>\Code{DH5E_auto_t_vers=1}</td> + <td>\ref H5E_auto1_t</td> + </tr> + <tr> + <td>\Code{DH5E_auto_t_vers=2}</td> + <td>\ref H5E_auto2_t</td> + </tr> + <tr> + <td rowspan="2">H5Ewalk()</td> + <td>\Code{DH5Ewalk_vers=1}</td> + <td>H5Ewalk1() <br/> with callback \ref H5E_walk1_t <br/> and struct \ref H5E_error1_t</td> + </tr> + <tr> + <td>\Code{DH5Ewalk_vers=2}</td> + <td>H5Ewalk2() <br/> with callback \ref H5E_walk2_t <br/> and struct \ref H5E_error2_t</td> + </tr> + <tr> + <td rowspan="2">H5Gcreate()</td> + <td>\Code{DH5Gcreate_vers=1}</td> + <td>H5Gcreate1()</td> + </tr> + <tr> + <td>\Code{DH5Gcreate_vers=2}</td> + <td>H5Gcreate2()</td> + </tr> + <tr> + <td rowspan="2">H5Gopen()</td> + <td>\Code{DH5Gopen_vers=1}</td> + <td>H5Gopen1()</td> + </tr> + <tr> + <td>\Code{DH5Gopen_vers=2}</td> + <td>H5Gopen2()</td> + </tr> + <tr> + <td rowspan="2">H5Pget_filter()</td> + <td>\Code{DH5Pget_filter_vers=1}</td> + <td>H5Pget_filter1()</td> + </tr> + <tr> + <td>\Code{DH5Pget_filter_vers=2}</td> + <td>H5Pget_filter2()</td> + </tr> + <tr> + <td rowspan="2">H5Pget_filter_by_id()</td> + <td>\Code{DH5Pget_filter_by_id_vers=1}</td> + <td>H5Pget_filter_by_id1()</td> + </tr> + <tr> + <td>\Code{DH5Pget_filter_by_id_vers=2}</td> + <td>H5Pget_filter_by_id2()</td> + </tr> + <tr> + <td rowspan="2">H5Pinsert()</td> + <td>\Code{DH5Pinsert_vers=1}</td> + <td>H5Pinsert1()</td> + </tr> + <tr> + <td>\Code{DH5Pinsert_vers=2}</td> + <td>H5Pinsert2()</td> + </tr> + <tr> + <td rowspan="2">H5Pregister()</td> + <td>\Code{DH5Pregister_vers=1}</td> + <td>H5Pregister1()</td> + </tr> + <tr> + <td>\Code{DH5Pregister_vers=2}</td> + <td>H5Pregister2()</td> + </tr> + <tr> + <td rowspan="2">H5Rget_obj_type()</td> + <td>\Code{DH5Rget_obj_typevers=1}</td> + <td>H5Rget_obj_type1()</td> + </tr> + <tr> + <td>\Code{DH5Rget_obj_type_vers=2}</td> + <td>H5Rget_obj_type2()</td> + </tr> + <tr> + <td rowspan="2">H5Tarray_create()</td> + <td>\Code{DH5Tarray_create_vers=1}</td> + <td>H5Tarray_create1()</td> + </tr> + <tr> + <td>\Code{DH5Tarray_create_vers=2}</td> + <td>H5Tarray_create2()</td> + </tr> + <tr> + <td rowspan="2">H5Tcommit()</td> + <td>\Code{DH5Tcommit_vers=1}</td> + <td>H5Tcommit1()</td> + </tr> + <tr> + <td>\Code{DH5Tcommit_vers=2}</td> + <td>H5Tcommit2()</td> + </tr> + <tr> + <td rowspan="2">H5Tget_array_dims()</td> + <td>\Code{DH5Tget_array_dims_vers=1}</td> + <td>H5Tget_array_dims1()</td> + </tr> + <tr> + <td>\Code{DH5Tget_array_dims_vers=2}</td> + <td>H5Tget_array_dims2()</td> + </tr> + <tr> + <td rowspan="2">H5Topen()</td> + <td>\Code{DH5Topen_vers=1}</td> + <td>H5Topen1()</td> + </tr> + <tr> + <td>\Code{DH5Topen_vers=2}</td> + <td>H5Topen2()</td> + </tr> + <tr> + <td rowspan="2">\ref H5Z_class_t struct for H5Zregister()</td> + <td>\Code{DH5Z_class_t_vers=1}</td> + <td>\ref H5Z_class1_t</td> + </tr> + <tr> + <td>\Code{DH5Z_class_t_vers=2}</td> + <td>\ref H5Z_class2_t</td> + </tr> + </table> + </div> + + \subsubsection further Further Information + It is possible to specify multiple function mappings for a single application build: + \code{.sh} + h5cc ... -DH5Rdereference_vers=1 -DH5Fget_info_vers=2 ... + \endcode + As a result of the function and struct mappings in this compile example, all + occurrences of the macro \Code{H5Rdereference} will be mapped to \Code{H5Rdereference1} + and all occurrences of the macro \Code{H5Fget_info} will be mapped to \Code{H5Fget_info2} + for the application being built. + + The function and struct mappings can be used to guarantee that a given API compatibility + macro will be mapped to the desired underlying function or struct version regardless of + the library or application mappings. In cases where an application may benefit greatly + from features offered by some of the later APIs, or must continue to use some earlier + API versions for compatibility reasons, this fine-grained control may be very important. + + As noted earlier, the function mappings can only reference versioned functions that are + included in the HDF5 library, as determined by the configure flag used to build the + library. For example, if the HDF5 library being linked with the application was built + with the \Code{--disable-deprecated-symbols} option, version 1 of the underlying functions + would not be available, and the example above that defined \Code{H5Rdereference_vers=1} + would not be supported. + + The function mappings do not negate any available functions. If \Code{H5Rdereference1} + is available in the installed version of the HDF5 library, and the application was not + compiled with the \Code{-DH5_NO_DEPRECATED_SYMBOLS} flag, the function \Code{H5Rdereference1} + will remain available to the application through its versioned name. Similarly, + \Code{H5Rdereference2} will remain available to the application as \Code{H5Rdereference2}. + The function mapping version flag \Code{H5Rdereference_vers} only controls the mapping of + the API compatibility macro \Code{H5Rdereference} to one of the two available functions. + + This can be especially useful in any case where the programmer does not have direct control + over global macro definitions, such as when writing code meant to be copied to multiple + applications or when writing code in a header file. + + \section macros Compatibility Macros in HDF5 1.6.8 and Later + A series of similar compatibility macros were introduced into the release 1.6 + series of the library, starting with release 1.6.8. These macros simply alias the + '1' version functions, callbacks, and typedefs listed above to their original + non-numbered names. + + These macros were strictly a forward-looking feature at that time; they were not + necessary for compatibility in 1.6.x. These macros were created at that time to + enable writing code that could be used with any version of the library after 1.6.8 + and any library compilation options except \Code{H5_NO_DEPRECATED_SYMBOLS}, by always + using the '1' version of versioned functions and types. For example, \Code{H5Dopen1} + will always be interpreted in exactly the same manner by any version of the library + since 1.6.8. + + \section use-case Common Use Case + A common scenario where the API compatibility macros may be helpful is the migration + of an existing application to a new HDF5 release. An incremental migration plan is + outlined here: + <ol> + <li>Build the HDF5 library without specifying any library mapping \Code{configure} + flag. In this default mode, the 1.6.x, 1.8.x, and 1.10.x versions of the + underlying functions are available, and the API compatibility macros will + be mapped to the current HDF5 versioned functions.</li> + <li>Compile the application with the \Code{-DH5_USE_NN_API} application mapping + option if it was written for use with an earlier HDF5 library. Because the + application mapping overrides the library mapping, the macros will all be + mapped to the earlier versions of the functions.</li> + <li>Remap one API compatibility macro at a time (or sets of macros), to use the + current HDF5 versions. At each stage, use the function mappings to map the macros + being worked on to the current versions. For example, use the + \Code{-DH5Rdereference_vers=2} version flag setting to remap the \Code{H5Rdereference} + macro to \Code{H5Rdereference2}, the 1.10.x version. + + During this step, the application code will need to be modified to change the calling + parameters used with the API compatibility macros to match the number and type + of the 1.10.x versioned functions. The macro name, for example \Code{H5Rdereference}, + should continue to be used in the code, to allow for possible re-mappings to later + versioned functions in a future release.</li> + <li>After all macros have been migrated to the latest versioned functions in step 3, + compile the application without any application or function mappings. This build + uses the library mappings set in step 1, and maps API compatibility macros to the + latest versions.</li> + <li>Finally, compile the application with the application mapping + \Code{-DH5_NO_DEPRECATED_SYMBOLS}, and address any failures to complete + the application migration process.</li> + </ol> + + */
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