зеркало из https://github.com/microsoft/vcpkg.git
49 строки
1.5 KiB
CMake
49 строки
1.5 KiB
CMake
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#[===[.md:
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# z_vcpkg_forward_output_variable
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This macro helps with forwarding values from inner function calls,
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through a local function scope, into pointer out parameters.
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```cmake
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z_vcpkg_forward_output_variable(ptr_to_parent_var var_to_forward)
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```
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is equivalent to
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```cmake
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if(DEFINED ptr_to_parent_var)
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if(DEFINED value_var)
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set("${ptr_to_parent_var}" "${value_var}" PARENT_SCOPE)
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else()
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unset("${ptr_to_parent_var}" PARENT_SCOPE)
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endif()
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endif()
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```
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Take note that the first argument should be a local variable that has a value of the parent variable name.
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Most commonly, this local is the result of a pointer-out parameter to a function.
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If the variable in the first parameter is not defined, this function does nothing,
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simplifying functions with optional out parameters.
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Most commonly, this should be used in cases like:
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```cmake
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function(my_function out_var)
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file(SHA512 "somefile.txt" local_var)
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z_vcpkg_forward_output_variable(out_var local_var)
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endfunction()
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```
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#]===]
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macro(z_vcpkg_forward_output_variable ptr_to_parent_var var_to_forward)
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if("${ARGC}" GREATER "2")
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message(FATAL_ERROR "z_vcpkg_forward_output_variable was passed extra arguments: ${ARGN}")
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endif()
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if(DEFINED "${ptr_to_parent_var}")
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if(DEFINED "${var_to_forward}")
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set("${${ptr_to_parent_var}}" "${${var_to_forward}}" PARENT_SCOPE)
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else()
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unset("${${ptr_to_parent_var}}" PARENT_SCOPE)
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endif()
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endif()
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endmacro()
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