Re: is standard for COMPATIBLE_MACHINE to use "()" or not?

["Robert P. J. Day" <rpjday@crashcourse.ca>]

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On Fri, 6 Mar 2015, Mike Looijmans wrote:

> On 05-03-15 09:43, Robert P. J. Day wrote:
> >
> >    a style guide thing ... it appears that COMPATIBLE_MACHINE happily
> > acccepts a matching RE within parentheses or not, is there a
> > preference?
> >
> >    also, in checking that, i ran across this in oe-core:
> >
> > linux-yocto_3.14.bb:COMPATIBLE_MACHINE =
> > "qemuarm|qemuarm64|qemux86|qemuppc|qemumips|qemumips64|qemux86-64"
> > linux-yocto_3.19.bb:COMPATIBLE_MACHINE =
> > "qemuarm|qemuarm64|qemux86|qemuppc|qemumips|qemumips64|qemux86-64"
> > linux-yocto-dev.bb:COMPATIBLE_MACHINE =
> > "(qemuarm|qemux86|qemuppc|qemumips|qemumips64|qemux86-64)"
>
> The regex should have been "qemu(arm|x86|ppc|mips|mips64|x86-64)"
>
> And since "x86-64" already matches "x86", that could have been omitted.
>
> > where the first two recipes list "qemuarm64" but the dev version
> > doesn't ... is that deliberate?
>
> Probably not, but "qemuarm64" matches "qemuarm" already.

  more nitpcking pedantry, but as i read it from the python code in
base.bbclass:

        need_machine = d.getVar('COMPATIBLE_MACHINE', True)
        if need_machine:
            import re
            compat_machines = (d.getVar('MACHINEOVERRIDES', True) or "").split(":")
            for m in compat_machines:
                if re.match(need_machine, m):
                    break

the "re.match"ing does not implicitly anchor the RE to the beginning
or end of string, correct? it couldn't, or "qemuarm64" could not
possibly match "qemuarm".

  does that not suggest that one should add those anchors to avoid the
(admittedly unlikely) situation where i define a machine named, say,
"rdayqemux86" which, as i read it, will match a "qemux86" machine even
if i didn't want it to? would i then avoid this by setting:

  COMPATIBLE_MACHINE = "^rdayqemu"

to match *all* machines whose names *start* with "rdayqemu"? this
really isn't explained carefully anywhere i can see.

rday

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Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
LinkedIn:                               http://ca.linkedin.com/in/rpjday
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