[Scons-users] Scanners

Brian Cody brian.j.cody at gmail.com
Wed Jan 20 09:20:20 EST 2016


Silly question--does the implicit dependency order actually matter? I know
the sources list does. I ask because I've made plenty of scanners and I've
never knowingly run into a rebuild due to the implicit dependency order
changing.
On Jan 20, 2016 9:08 AM, "Tom Tanner (BLOOMBERG/ LONDON)" <
ttanner2 at bloomberg.net> wrote:

> There are many things that can cause the generated lists of dependencies
> to change order. mostly these are concerned with getting lists from glob,
> but it also can happen if you change the scanners mechanism which can
> result in getting the same list but in a different order. I changed my
> python scanner recently to use the python ast library to determine imports,
> rather than regexes. This works great, but it finds and process things in a
> slightly different order to how it used to
>
> From: wblevins001 at gmail.com At: Jan 20 2016 13:52:54
> To: Tom Tanner (BLOOMBERG/ LONDON) <ttanner2 at bloomberg.net>,
> scons-users at scons.org
> Subject: Re: [Scons-users] Scanners
>
> I don't believe there is a magic switch for this. I assume the real issue
> is that the order of the dependencies must always be the same, and not
> necessarily sorted alphabetically. What tool are you using that requires
> sorting? Is this related to caching?
>
> V/R,
> William
>
>
>
> On Wed, Jan 20, 2016 at 11:22 AM, Tom Tanner (BLOOMBERG/ LONDON) <
> ttanner2 at bloomberg.net> wrote:
>
>> Is there any way to tell the Scanner class to sort the list of scanned
>> dependencies? I have a hand written scanner and it has to sort the
>> dependencies it returns so as not to get unexpected rebuilds depending on
>> the vagaries of todays choice of filing system and how python has decided
>> to order dictionaries today.
>>
>> But even that isn't always enough as the scanner is recursive so it can
>> possibly build multiple lists which are individually sorted but the total
>> result isn't.
>>
>> But at least specifically in my case, and possibly in others, the order
>> of the dependencies isn't important.
>>
>> Note: I'm using the scanner factory to create my scanner which I see is
>> sort-of-deprecated, but it's the one I found the documentation when writing
>> my scanner in the first place.
>>
>>
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>
>
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