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RE: Desire clarification of 'override' behavior

From: Krejsa, Dan
Subject: RE: Desire clarification of 'override' behavior
Date: Tue, 11 Sep 2007 11:38:32 -0700

Hi Paul,

Thanks for the clarification!  It isn't clear from the
documentation that 'override' changes the 'power' needed
to subsequently set a variable (although one eventually
finds out ;-).

- Dan 

-----Original Message-----
From: Paul Smith [mailto:address@hidden 
Sent: Tuesday, September 11, 2007 11:33 AM
To: Krejsa, Dan
Cc: address@hidden
Subject: Re: Desire clarification of 'override' behavior

"Krejsa, Dan" <address@hidden> writes:
> However, using 'override' also seems to prevent subsequent assignments
> to the variable, done within the Makefile without 'override', from
> taking effect, as if using 'override' made the variable look as if it
> had been defined on the command line.  This does not appear to be
> documented.

This behavior is correct, although your description of it is not quite
correct.  Also, both examples given in the mailing list message you
reference are correct; there is no bug here.

The "override" keyword applies to only that particular setting of the
variable, with which it is associated.  It doesn't "reset" the variable
to be a normal make variable which is then able to be modified as if it
were never set on the command line.  There is no way to do that.

Once a variable is set via "override", the most powerful type of
setting, there's no way it can be modified further unless all further
modifications ALSO use "override".  Any lesser setting (including from
the command line, makefile, environment, etc.) will be ignored.

I agree this should be made explicit in the documentation.

 Paul D. Smith <address@hidden>
 "Please remain calm--I may be mad, but I am a professional."--Mad

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