Question

[pzz2011]

感觉对unset的行为有点困惑。

An option that the user can select. Can accept condition to control when option is available for user.

Usage:

mxnet_option(<option_variable> "doc string" [IF ])

function(mxnet_option variable description value)
set(__value ${value})
set(__condition "")
set(__varname "__value")
foreach(arg ${ARGN})
if(arg STREQUAL "IF" OR arg STREQUAL "if")
set(__varname "__condition")
else()
list(APPEND ${__varname} ${arg})
endif()
endforeach()
unset(__varname) ==========>这里为什么要unset() unset之后这个变量不是不起作用？
if("${__condition}" STREQUAL "")
set(__condition 2 GREATER 1)
endif()

if(${__condition})
if("${__value}" MATCHES ";")
if(${__value})
option(${variable} "${description}" ON)
else()
option(${variable} "${description}" OFF)
endif()
elseif(DEFINED ${__value})
if(${__value})
option(${variable} "${description}" ON)
else()
option(${variable} "${description}" OFF)
endif()
else()
option(${variable} "${description}" ${__value})
endif()
else()
unset(${variable} CACHE)
endif()
endfunction()