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Diffstat (limited to 'Help/command/macro.rst')
| -rw-r--r-- | Help/command/macro.rst | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/Help/command/macro.rst b/Help/command/macro.rst index 33249c9..6bee69c 100644 --- a/Help/command/macro.rst +++ b/Help/command/macro.rst @@ -24,6 +24,10 @@ This facilitates creating macros with optional arguments. Additionally ``${ARGV}`` holds the list of all arguments given to the macro and ``${ARGN}`` holds the list of arguments past the last expected argument. +Referencing to ``${ARGV#}`` arguments beyond ``${ARGC}`` have undefined +behavior. Checking that ``${ARGC}`` is greater than ``#`` is the only +way to ensure that ``${ARGV#}`` was passed to the function as an extra +argument. See the :command:`cmake_policy()` command documentation for the behavior of policies inside macros. @@ -37,10 +41,15 @@ replacements much like the C preprocessor would do with a macro. Therefore you will NOT be able to use commands like:: if(ARGV1) # ARGV1 is not a variable + if(DEFINED ARGV2) # ARGV2 is not a variable + if(ARGC GREATER 2) # ARGC is not a variable foreach(loop_var IN LISTS ARGN) # ARGN is not a variable -In the first case you can use ``if(${ARGV1})``, in the second case, you can -use ``foreach(loop_var ${ARGN})`` but this will skip empty arguments. +In the first case, you can use ``if(${ARGV1})``. +In the second and third case, the proper way to check if an optional +variable was passed to the macro is to use ``if(${ARGC} GREATER 2)``. +In the last case, you can use ``foreach(loop_var ${ARGN})`` but this +will skip empty arguments. If you need to include them, you can use:: set(list_var "${ARGN}") |