[OE-core] what is meaning of "SRC_URI_append_whatever +=" ??

[Richard Purdie]

On Wed, 2012-03-21 at 11:11 +0000, Phil Blundell wrote:
> On Wed, 2012-03-21 at 06:28 -0400, Robert P. J. Day wrote:
> >   of course, if all of the above is perfectly valid, i'm going to be
> > embarrassed.
> 
> All the constructs you mentioned are syntactically valid, though it
> isn't clear that all of them are very useful.
> 
> There is a subtle difference between SRC_URI_append = "..." and
> SRC_URI_append += "..." in that the latter will insert a space whereas
> the former will not.  But I don't think there is any situation where
> this distinction serves any useful purpose.  As far as I know, with
> current bitbake at least,
> 
> SRC_URI = "a"
> SRC_URI_append = "b"
> SRC_URI_append += "c"
> 
> and
> 
> SRC_URI = "a"
> SRC_URI_append = "b"
> SRC_URI_append = " c"
> 
> will both produce exactly the same effect, viz. SRC_URI = "ab c".  I
> think it might have been the case with some older bitbakes that the
> middle line would have no effect in this situation but that doesn't
> appear to be true now.
> 
> >  SRC_URI_append = "..."                (why not just SRC_URI +=?)
> 

I hadn't realised the += combined with append would insert a space
although I can see why it would happen :)

Cheers,

Richard