question about meta/class/qmake-base.bbclass

question about meta/class/qmake-base.bbclass

[Kang Kai]

Hi Holger,

When I read the file  meta/class/qmake-base.bbclass, I find that that 
are 2 lines:
     unset QMAKESPEC || true
     ${OE_QMAKE_QMAKE} -makefile -spec ${QMAKESPEC} -o Makefile 
$QMAKE_VARSUBST_PRE $AFTER $PROFILES $QMAKE_VARSUBST_POST || die "Error 
calling ${OE_QMAKE_QMAKE} on $PROFILES"

I am confused that why unset QMAKESPEC first and then use it a argument 
for qmake?
Could you help me to get out of that?

Thanks and Regards,
Kai

Re: question about meta/class/qmake-base.bbclass

[Paul Eggleton]

On Monday 22 August 2011 10:42:42 Kang Kai wrote:
> When I read the file  meta/class/qmake-base.bbclass, I find that that
> are 2 lines:
>      unset QMAKESPEC || true
>      ${OE_QMAKE_QMAKE} -makefile -spec ${QMAKESPEC} -o Makefile
> $QMAKE_VARSUBST_PRE $AFTER $PROFILES $QMAKE_VARSUBST_POST || die "Error
> calling ${OE_QMAKE_QMAKE} on $PROFILES"
> 
> I am confused that why unset QMAKESPEC first and then use it a argument
> for qmake?

It's not obvious, but think that the difference here is between $QMAKESPEC and 
${QMAKESPEC} - the first one is a reference to an environment variable, the 
second is a reference to an OE/BitBake variable. So "unset QMAKESPEC" is just 
clearing out the environment variable; ${QMAKESPEC} would still have a value.

Cheers,
Paul

-- 

Paul Eggleton
Intel Open Source Technology Centre

Re: question about meta/class/qmake-base.bbclass

[Kang Kai]

On 2011年08月23日 02:46, Paul Eggleton wrote:
> On Monday 22 August 2011 10:42:42 Kang Kai wrote:
>> When I read the file  meta/class/qmake-base.bbclass, I find that that
>> are 2 lines:
>>       unset QMAKESPEC || true
>>       ${OE_QMAKE_QMAKE} -makefile -spec ${QMAKESPEC} -o Makefile
>> $QMAKE_VARSUBST_PRE $AFTER $PROFILES $QMAKE_VARSUBST_POST || die "Error
>> calling ${OE_QMAKE_QMAKE} on $PROFILES"
>>
>> I am confused that why unset QMAKESPEC first and then use it a argument
>> for qmake?
> It's not obvious, but think that the difference here is between $QMAKESPEC and
> ${QMAKESPEC} - the first one is a reference to an environment variable, the
> second is a reference to an OE/BitBake variable. So "unset QMAKESPEC" is just
> clearing out the environment variable; ${QMAKESPEC} would still have a value.
>
> Cheers,
> Paul
>
Hi Paul,

Thanks for your detailed answer.

Regards,
Kai

Re: question about meta/class/qmake-base.bbclass

[Kang Kai]

On 2011年08月22日 19:30, Holger Freyther wrote:
> On 08/22/2011 11:42 AM, Kang Kai wrote:
>> Hi Holger,
>>
>> I am confused that why unset QMAKESPEC first and then use it a argument for
>> qmake?
>> Could you help me to get out of that?
> Hi,
>
> it has been a long time and I can only speculate right now. It might have been
> that QMAKESPEC was not shell exported, and we really wanted to make sure that
> it is using the QMAKESPEC we use in the recipe. Alternatively  it might be a
> style issue, e.g. it is easier to see which spec is used by looking at the
> qmake invocation (also when changing the .pro in the ${S} the right spec would
> be used again).
>
> holger
>

Hi Holger,

Thanks for your reply, and I think I can understand them right now.

Thank you!
Kai