[Spice-devel] [PATCH spice-common] Meson: make use of features in 0.47

[Frediano Ziglio]

> 
> Spice-server and spice-gtk already require 0.47, and with this release,
> there were some interesting additions we can make use:
> 
>  - Options with 'feature' type:
> 
>    This built-in type is used instead of the tri-state string combo
>    (auto/true/false), simplifying the dependency checks.
> 
>    http://mesonbuild.com/Build-options.html#features
> 
>  - Dictionary:
> 
>    Easier to iterate and improves readability of the code by replacing
>    the use of nested lists.
> 
>    http://mesonbuild.com/Reference-manual.html#dictionary-object
> 
> Signed-off-by: Eduardo Lima (Etrunko) <etrunko at redhat.com>
> ---
>  meson.build       | 37 ++++++++++++++++---------------------
>  meson_options.txt |  7 ++-----
>  2 files changed, 18 insertions(+), 26 deletions(-)
> 
> diff --git a/meson.build b/meson.build
> index 226d9f4..6fa67dc 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -2,7 +2,7 @@
>  # project definition
>  #
>  project('spice-common', 'c',
> -         meson_version : '>= 0.45.0',
> +         meson_version : '>= 0.47.0',
>           license : 'LGPLv2.1')
>  
>  if not meson.is_subproject()
> @@ -98,32 +98,27 @@ endif
>  glib_version = '2.38'
>  glib_version_info = '>= @0@'.format(glib_version)
>  
> -deps = [['spice-protocol', '>= 0.12.12'],
> -        ['glib-2.0', glib_version_info],
> -        ['gio-2.0', glib_version_info],
> -        ['gthread-2.0', glib_version_info],
> -        ['pixman-1', '>= 0.17.7'],
> -        ['openssl', '>= 1.0.0']]
> +deps = {'spice-protocol' : '>= 0.12.12',
> +        'glib-2.0'       : glib_version_info,
> +        'gio-2.0'        : glib_version_info,
> +        'gthread-2.0'    : glib_version_info,
> +        'pixman-1'       : '>= 0.17.7',
> +        'openssl'        : '>= 1.0.0'}
>  
> -foreach dep : deps
> -  spice_common_deps += dependency(dep[0], version : dep[1])
> +foreach dep, version : deps
> +  spice_common_deps += dependency(dep, version : version)
>  endforeach
>  

surely more readable, note that dictionary does not keep
the order of the items while arrays does, but is not a problem
with current code.

>  #
>  # Non-mandatory/optional dependencies
>  #
> -optional_deps = [
> -                    ['celt051', '>= 0.5.1.1'],
> -                    ['opus', '>= 0.9.14'],
> -                ]
> -foreach dep : optional_deps
> -  option_value = get_option(dep[0])
> -  if option_value != 'false'
> -    d = dependency(dep[0], required: (option_value == 'true'), version :
> dep[1])
> -    if d.found()
> -      spice_common_deps += d
> -
> spice_common_config_data.set('HAVE_ at 0@'.format(dep[0].underscorify().to_upper()),
> '1')
> -    endif
> +optional_deps = {'celt051' : '>= 0.5.1.1',
> +                 'opus'    : '>= 0.9.14'}
> +foreach dep, version : optional_deps
> +  d = dependency(dep, required : get_option(dep), version : version)
> +  if d.found()
> +    spice_common_deps += d
> +
> spice_common_config_data.set('HAVE_ at 0@'.format(dep.underscorify().to_upper()),
> '1')
>    endif
>  endforeach
>  
> diff --git a/meson_options.txt b/meson_options.txt
> index b88f209..1b80257 100644
> --- a/meson_options.txt
> +++ b/meson_options.txt
> @@ -11,15 +11,12 @@ option('extra-checks',
>      description : 'Enable extra checks on code')
>  
>  option('celt051',
> -    type : 'combo',
> -    choices : ['true', 'false', 'auto'],
> -    value : 'auto',
> +    type : 'feature',
>      yield : true,
>      description: 'Enable celt051 audio codec')
>  
>  option('opus',
> -    type : 'combo',
> -    choices : ['true', 'false', 'auto'],
> +    type : 'feature',
>      yield : true,
>      description: 'Enable Opus audio codec')
>  

I would say yes.

What worry me is that this Meson looks like a moving target.
The fact that they don't want to add function requires them to
to write new and new modules/functions and have new releases.
The main concern for us is that is hard to predict when we could
remove autoconf stuff having to continue to maintain 2 build systems.
Will be hard to have Meson 0.47 in next RHEL7 which will mean we
need at least to wait other 6 months/1 year.

Maybe for older distros we could package Meson in a tarball and
use it inside higher packager (like spec file) to use a newer
meson without the needs to have it installed (I looked and there
are mainly python files so seems doable, just requires a recent
python3 installed in the system).

Frediano