[PATCH cygport] Add 'vars' command to output arbitrary .cygport variables

[Jon Turney]

On 28/05/2021 17:06, Brian Inglis wrote:
> On 2021-05-26 13:06, Jon Turney wrote:
>> Since variables in a .cygport file can be computed from arbitrary shell
>> expressions, perhaps containing variables that cygport itself defines,
>> other programs can't determine their value just by parsing the .cygport
>> file.
>>
>> Add 'vars' command to output arbitrary variables defined by the .cygport
>> file.
>>
>> The idea is that the output from this should be eval-able in a shell to
>> be further used, but it probably needs some additional escaping (of
>> newlines?) to be completely right in all cases.
>>
>> e.g
>>
>>> $ cygport libX11.cygport vars PVR BUILD_REQUIRES
>>> PVR='1.7.1-1'
>>> BUILD_REQUIRES='xtrans xorgproto libxcb-devel xmlto 
>>> xorg-sgml-doctools docbook-xml43'
>>
>>> eval $(cygport libX11.cygport vars BUILD_REQUIRES) ; for r in 
>>> ${BUILD_REQUIRES} ; do echo $r; done
> 
> bash "declare -p NAME..." seems to do what you want and produce 
> .source-able output:
> 
> $ ( . mingw64-x86_64-nghttp2/mingw64-x86_64-nghttp2.cygport; declare -p 
> BUILD_REQUIRES DESCRIPTION; echo echo \$BUILD_REQUIRES \$DESCRIPTION) | 
> bash -svx

Yeah, I should probably use 'declare -p'.

But just sourcing the .cygport is not adequate, as this can't determine 
variables which are generated by cygport itself (e.g. VR, 'inherit' for 
some cygclasses sets ARCH=noarch, etc.)