Re: [CMake] getting a build parameter from a file

2015-06-09 Thread David Cole via CMake 
Why not just use configure_file to write ${metals} into the file...
configure_file only actually touches/writes-to/updates the file if the
contents are different...

Then you can just depend on that file and you don't need a separate
timestamp file.


HTH,
David C.


On Tue, Jun 9, 2015 at 1:05 AM, Dave Yost d...@yost.com wrote:


 First, my cmake code does this:

 sets ${metals} from a cmake command-line argument
 compares the contents of ${metals} against the contents of a file to note
 whether the variable is being changed since the last run of cmake
 writes the new value to that file for next time
 call an add_timestamp_file_target function. which touches the file
 metalsTimestamp if the variable is being changed or if the file doesn’t
 exist.

 Then comes this:

 set(CMAKE_CXX_FLAGS ${CMAKE_CXX_FLAGS} -DMETALS=${metals})
 add_executable   (metals metals.cc)
 add_dependencies (metals metalsTimestamp)


 My add_timestamp_file_target function has to use one of
add_custom_target
add_custom_command
 to make metalsTimestamp visible to the add_dependencies function.

 Problem is, it seems that those commands have to touch the file every time
 cmake runs, but I want to touch it only when necessary.

 Is there a way to make this work?


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Re: [CMake] getting a build parameter from a file

2015-06-09 Thread Dave Yost 

 On 2015-06-09, at 8:05 AM, David Cole dlrd...@aol.com wrote:
 
 Why not just use configure_file

because I didn’t know about it. Thanks!

 to write ${metals} into the file...
 configure_file only actually touches/writes-to/updates the file if the
 contents are different...
 
 Then you can just depend on that file and you don't need a separate
 timestamp file.
 
 
 HTH,
 David C.
 
 
 On Tue, Jun 9, 2015 at 1:05 AM, Dave Yost d...@yost.com wrote:
 
 
 First, my cmake code does this:
 
 sets ${metals} from a cmake command-line argument
 compares the contents of ${metals} against the contents of a file to note
 whether the variable is being changed since the last run of cmake
 writes the new value to that file for next time
 call an add_timestamp_file_target function. which touches the file
 metalsTimestamp if the variable is being changed or if the file doesn’t
 exist.
 
 Then comes this:
 
 set(CMAKE_CXX_FLAGS ${CMAKE_CXX_FLAGS} -DMETALS=${metals})
 add_executable   (metals metals.cc)
 add_dependencies (metals metalsTimestamp)
 
 
 My add_timestamp_file_target function has to use one of
   add_custom_target
   add_custom_command
 to make metalsTimestamp visible to the add_dependencies function.
 
 Problem is, it seems that those commands have to touch the file every time
 cmake runs, but I want to touch it only when necessary.
 
 Is there a way to make this work?
 
 
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[CMake] getting a build parameter from a file

2015-06-08 Thread Dave Yost 


First, my cmake code does this:
sets ${metals} from a cmake command-line argument
compares the contents of ${metals} against the contents of a file to note 
whether the variable is being changed since the last run of cmake
writes the new value to that file for next time
call an add_timestamp_file_target function. which touches the file 
metalsTimestamp if the variable is being changed or if the file doesn’t exist.
Then comes this:
set(CMAKE_CXX_FLAGS ${CMAKE_CXX_FLAGS} -DMETALS=${metals})
add_executable   (metals metals.cc http://metals.cc/)
add_dependencies (metals metalsTimestamp)

My add_timestamp_file_target function has to use one of
   add_custom_target
   add_custom_command
to make metalsTimestamp visible to the add_dependencies function.

Problem is, it seems that those commands have to touch the file every time 
cmake runs, but I want to touch it only when necessary.

Is there a way to make this work?

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