Auto-generated XML interfaces and dependencies

Brad King brad.king at
Sat Dec 29 17:13:35 CET 2007

Alexander Neundorf wrote:
> Ok, so in one directory the xml file is created using add_custom_command(), 
> and used later on in targets in other directories.
> The official way to express the dependency to a generated file is to add the 
> generated file to the sources of the target.


> I'm not quite sure how the dependencies are handled between directories.
> Brad ?

Custom commands are only hooked into targets in the same directory in 
which they are defined (not even subdirectories).

> I guess then one way would be to add a helper target
> add_custom_target(CREATE_DBUS_STUFF)
> which creates all the dbus xml interfaces, and have all the targets which need 
> these interfaces depend on this helper target.

Using a target-level dependency is the correct approach.  Having the 
rule to generate the file in more than one target could result in 
corruption during parallel builds.

> OTOH, if other targets need some part of what is built when kmail is being 
> built, then it doesn't seem to be that wrong to make them depend on kmail (or 
> the helper target).

Any approach that puts the generation rule in a single target on which 
all other targets that use the file depend is correct.  Avoiding a 
helper target in favor of a target on which a dependency must be added 
anyway is probably good.


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