[CMake] How to skip steps and use default values in ExternalProject_Add command?

[Cedric Doucet]

Thank you very much for your help, Petr! 
I will try it! 
Cheers, 
Cédric 

----- Mail original -----

> De: "Petr Kmoch" <petr.kmoch at gmail.com>
> À: "Cedric Doucet" <cedric.doucet at inria.fr>
> Cc: cmake at cmake.org
> Envoyé: Jeudi 21 Mai 2015 14:21:48
> Objet: Re: [CMake] How to skip steps and use default values in
> ExternalProject_Add command?

> No idea on this one. The trick I showed is "vanilla CMake," a direct
> consequence of the CMake parsing & string processing algorithm. What you're
> asking is about the internals of ExternalProject_Add, of which I know
> nothing.

> Petr

> On Thu, May 21, 2015 at 1:43 PM, Cedric Doucet < cedric.doucet at inria.fr >
> wrote:

> > Hi Petr!
> 

> > Thank you for the trick: it's very powerful!
> 

> > Does this mean that these two calls are equivalent if I write:
> > set(the_configure_command CONFIGURE_COMMAND) ?
> 

> > ExternalProject_Add(${${LIBRARY}_LOWERNAME}
> 
> > PREFIX ${${LIBRARY}_PREFIX}
> 
> > URL ${${LIBRARY}_URL}
> 
> > ${the_configure_command}
> 
> > )
> 

> > ExternalProject_Add(${${LIBRARY}_LOWERNAME}
> 
> > PREFIX ${${LIBRARY}_PREFIX}
> 
> > URL ${${LIBRARY}_URL}
> 
> > )
> 

> > I guess the default value of CONFIGURE_COMMAND will be used, right?
> 

> > Cédric
> 

> > > De: "Petr Kmoch" < petr.kmoch at gmail.com >
> > 
> 
> > > À: "Cedric Doucet" < cedric.doucet at inria.fr >
> > 
> 
> > > Cc: cmake at cmake.org
> > 
> 
> > > Envoyé: Jeudi 21 Mai 2015 13:33:27
> > 
> 
> > > Objet: Re: [CMake] How to skip steps and use default values in
> > > ExternalProject_Add command?
> > 
> 

> > > Hi Cedric.
> > 
> 

> > > When doing things like that, remember that CMake's "named arguments" are
> > > arguments just like any other. So you can easily obtain them from
> > > variable
> > > expansion; something like this:
> > 
> 

> > > if(${LIBRARY}_CONFIGURE_COMMAND)
> > 
> 
> > > set(the_configure_command CONFIGURE_COMMAND
> > > ${${LIBRARY}_CONFIGURE_COMMAND})
> > 
> 
> > > else()
> > 
> 
> > > set(the_configure_command "")
> > 
> 
> > > endif()
> > 
> 

> > > ExternalProject_Add(${${LIBRARY}_LOWERNAME}
> > 
> 
> > > PREFIX ${${LIBRARY}_PREFIX}
> > 
> 
> > > URL ${${LIBRARY}_URL}
> > 
> 
> > > ${the_configure_command}
> > 
> 
> > > BUILD_COMMAND ${${LIBRARY}_BUILD_COMMAND}
> > 
> 
> > > INSTALL_COMMAND ${${LIBRARY}_INSTALL_COMMAND}
> > 
> 
> > > )
> > 
> 

> > > The same trick can be applied to any other command you need to
> > > conditionally
> > > exclude, of course.
> > 
> 

> > > Petr
> > 
> 

> > > On Thu, May 21, 2015 at 1:10 PM, Cedric Doucet < cedric.doucet at inria.fr >
> > > wrote:
> > 
> 

> > > > Hello,
> > > 
> > 
> 

> > > > I would like to loop on a list of libraries to download and install, by
> > > > calling the ExternalProject_Add command for each of these libraries.
> > > 
> > 
> 
> > > > To do that, I need to define some commands for each library, like
> > > > CONFIGURE_COMMAND, BUILD_COMMAND and INSTALL_COMMAND.
> > > 
> > 
> 
> > > > These commands may differ from one library to another; for example,
> > > > some
> > > > of
> > > > them may be based on make, or autoconfig, or cmake, etc.
> > > 
> > 
> 
> > > > Furthermore, some of these libraries may not need to be built.
> > > 
> > 
> 

> > > > What is the good way to skip some steps?
> > > 
> > 
> 
> > > > Is it possible to use default values for some commands?
> > > 
> > 
> 

> > > > The problem in my situation is that I have to fill in each command
> > > > since
> > > > I
> > > > want to design way of downloading and installing third party libraries.
> > > 
> > 
> 
> > > > To be clear, I wrote a loop which looks like this:
> > > 
> > 
> 

> > > > ==========================================================================
> > > 
> > 
> 
> > > > foreach(LIBRARY IN LISTS NOT_FOUND_LIBRARIES)
> > > 
> > 
> 
> > > > ExternalProject_Add(${${LIBRARY}_LOWERNAME}
> > > 
> > 
> 
> > > > PREFIX ${${LIBRARY}_PREFIX}
> > > 
> > 
> 
> > > > URL ${${LIBRARY}_URL}
> > > 
> > 
> 
> > > > CONFIGURE_COMMAND ${${LIBRARY}_CONFIGURE_COMMAND}
> > > 
> > 
> 
> > > > BUILD_COMMAND ${${LIBRARY}_BUILD_COMMAND}
> > > 
> > 
> 
> > > > INSTALL_COMMAND ${${LIBRARY}_INSTALL_COMMAND}
> > > 
> > 
> 
> > > > )
> > > 
> > 
> 
> > > > endforeach(LIBRARY)
> > > 
> > 
> 
> > > > ==========================================================================
> > > 
> > 
> 

> > > > However, if a library is based on cmake, I do not need to specify
> > > > commands
> > > > for configuration and building.
> > > 
> > 
> 
> > > > Is it possible to say that the default value of CONFIGURE_COMMAND will
> > > > be
> > > > used for example?
> > > 
> > 
> 
> > > > The only way I know to do that is to suppress the line defining
> > > > CONFIGURE_COMMAND but I can't do that since other libraries may need to
> > > > define it.
> > > 
> > 
> 

> > > > To skip steps, I replace the corresponding command by 'ls' but it's not
> > > > very
> > > > clean.
> > > 
> > 
> 
> > > > That is to say, the value of ${LIBRARY}_CONFIGURE_COMMAND is 'ls' when
> > > > I
> > > > want
> > > > to skip the configuration step.
> > > 
> > 
> 

> > > > Thank you very much for your help.
> > > 
> > 
> 

> > > > Cédric
> > > 
> > 
> 

> > > > --
> > > 
> > 
> 

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