AVRO-3088: [C++] Export CMake package config file #3299
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| find_package (Boost 1.70 REQUIRED CONFIG COMPONENTS system) | ||
| if (TARGET Boost::system) | ||
| message("Found Boost version: ${Boost_VERSION}") | ||
| else () | ||
| message(FATAL_ERROR "Boost::system not found") | ||
| endif () |
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You mark this dependency as required. I think this check if target exists is not needed. CMake will fail if it does not find Boost and all requested components.
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I just want to make sure that the target with Boost:: namespace exists. Same for Snappy::snappy and ZLIB::ZLIB
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Snappy and ZLIB are not marked as required.
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Boost is not required. It is required only when AVRO_BUILD_TESTS or AVRO_USE_BOOST is enabled.
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I think what @mitjap was trying to say is that this if statement is superfluous as find_package is called with a REQUIRED keyword. It will fail by itself when Boost::system is not found, no need for doing it explicitly
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This is slightly different. CMIW, sometimes Boost::system target is not available even if Boost_FOUND is true since older Boost distributions may not add Boost:: namespace.
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I'd say in that case maybe reflect this in an error message? At this point Boost::system is definitely available. But it would not be available as a target.
Not sure however what would be the best error message in that case.
| configure_package_config_file( | ||
| "${CMAKE_CURRENT_SOURCE_DIR}/cmake/AvroConfig.cmake.in" | ||
| "${CMAKE_CURRENT_BINARY_DIR}/AvroConfig.cmake" | ||
| INSTALL_DESTINATION lib/cmake/Avro |
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I see an inconsistency here. The headers are installed in include/avro while cmake files are in lib/cmake/Avro. Maybe it should be lib/cmake/avro instead?
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This is a case-sensitive package name and it affects the behavior of calling find_package by downstream.
lib/cmake/avro->find_package(avro)lib/cmake/Avro->find_package(Avro)
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I'm actually not sure which one is more preferable here. I'll probably want to hear from the committers to this repo regarding the naming.
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In my (poor) experience the convention is to use the one with the capital letter.
What is the purpose of the change
Verifying this change
I have manually verified that the exported config file can be used by downstream projects like below:
Documentation