[CMake] How best to capture the current Date/Time

[Michael Jackson]

On Mar 20, 2009, at 10:12 AM, Bill Hoffman wrote:

> Michael Jackson wrote:
>> On Mar 20, 2009, at 5:30 AM, Eric Noulard wrote:
>>> 2009/3/20 Philip Lowman <philip at yhbt.com>:
>>>> On Thu, Mar 19, 2009 at 11:18 PM, Michael Jackson
>>>> <mike.jackson at bluequartz.net> wrote:
>>>>>
>>>>> I am trying to find a nice portable solution for generating  
>>>>> version
>>>>> strings based on the date (seems reasonable). I even have my own  
>>>>> c++ code
>>>>> that can generate the proper string for me. The problem that I  
>>>>> can not seem
>>>>> to get my head around is that I need to compile and run the  
>>>>> program at cmake
>>>>> time which probably isn't really going to happen, at least easily.
>>>>> So. what is everyone else doing for this?
>>>>>
>>>>> My main goal is to automate the generation of cmake code like the
>>>>> following:
>>>>>
>>>>> set ( ${${Project_Name}_VERSION} "2009.03.10")
>>>>>
>>>>> so that I can later use it for OS X bundle building.
>>>>>
>>>>> On Unix systems I can easily spawn a "date" command to get what  
>>>>> I need but
>>>>> what to do on windows?
>>>
>>> I use 'date' on unix and nothing but a "nodate" string on  
>>> windows :-(
>>>
>>>>
>>>> Ugly, but apparently possible with batch file scripting!
>>>> http://www.tech-recipes.com/rx/956/windows-batch-file-bat-to-get-current-date-in-mmddyyyy-format/
>>>>
>>>> Another option is you could write a small program which uses  
>>>> localtime() and
>>>> other posix functions to get you the format that you want and  
>>>> then use the
>>>> output from the program via a CHECK_C_SOURCE_COMPILES configure  
>>>> test.
>>>
>>> may be the same idea, use TRY_RUN with your home made portable  
>>> source
>>> to get your string at CMake time.
>>>
>>> another solution would be to try to find some script language  
>>> installed
>>> (perl, python, ...) then EXECUTE_PROCESS with appropriate pieces  
>>> of code
>>> for getting the date you want.
>>>
>>> I think it would be worth a feature request for cmake -E date  
>>> <format>
>>> the "how to get date" is popping again and again.
>>>
>>> -- 
>>> Erk
>> That was the ticket. The try_run is working as best as I would  
>> expect it to. I plan to wrap that code in a CMake variable so that  
>> I can trigger the try_run when I need to increment the version  
>> string.
>> After all of this I'll probably put in a feature request for this  
>> functionality to be a part of CMake. Actually, if we could just get  
>> the following variables set by CMake it would be great:
>> CMAKE_CURRENT_YEAR
>> CMAKE_CURRENT_MONTH
>> CMAKE_CURRENT_DAY
>> CMAKE_CURRENT_HOUR
>> CMAKE_CURRENT_MINUTE
>> CMAKE_CURRENT_SECOND
> I don't think you could do this as a set of variables.  It would be  
> better as some sort of command.  file(GETDATE result) or something.
>
> -Bill

Well, I could but I am really interested in _why_ I would _not_ want  
to? Besides the obvious that the variables would basically change  
every time that cmake ran which might have some unwanted side effects.

Mike