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

[Cedric Doucet]

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 

----- 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 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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