[cmake-developers] Bad error message when a package could not be found - make find_package() not search config files by default

[Brad King]

On 2/16/2012 8:19 AM, Alexander Neundorf wrote:
> Comments, objections ?

The entire point of find_package's interface is that the caller
does not need to care how the package is found, and the actual
method used for the find can change under the hood.

Ideally every package would provide a package config file in its
installation and we would never need Find modules.  In that case
having the extra keyword in every find_package call would be ugly.

If you don't like the error message then you are free to write

   find_package(Foo NO_MODULE)

anywhere you want.  Perhaps you can add an alternative keyword so
that this can be written

   find_package(Foo CONFIG)

instead for those authors who want to do so.  Furthermore if you
want to guarantee that a Find module is used then add a mode like

   find_package(Foo MODULE)

so that the command knows that it is an error if FindFoo does not
exist in CMAKE_MODULE_PATH.

In any of the above modes the error message can be more explicit.
It is up to the author of the project to choose to do this.  I do
not want it to be required.

For the default case perhaps the wording can be better than it is
now.  Currently the wording is trying to cover both the case that
the developer of the code is reading it and the case that an end
user is reading it while running cmake to build a project.  The
two cases are very different.

This is not the first time we've had to deal with messages that
are readable by developers but not by users and vice versa.  I
wonder if we should introduce some kind of use case mode setting
that tells CMake who will be reading the messages.  Then they
can be tailored more effectively to the context.

-Brad