[Scons-dev] Question about SCons CSIG behavior

[William Blevins]

I think that treating an empty file and a missing file equivalently is
dangerous because they are in no way semantically equivalent.  It is common
practice in software to use an empty file as a lock (like with
Side-effects).

If nothing else, this makes debugging csig information difficult because
missing files have signatures.

Unless someone is extremely opposed.  I will create an issue on for this if
it turns out not to be a quick patch.

V/R,
William

On Sat, Aug 15, 2015 at 6:40 PM, anatoly techtonik <techtonik at gmail.com>
wrote:

> On Thu, Jul 30, 2015 at 8:02 PM, William Blevins <wblevins001 at gmail.com>
> wrote:
>
>> Team,
>>
>> I noticed something peculiar when examining how CSIG's are generated for
>> Nodes.  In the case that get_content returns an error (IE. file is
>> missing), then the signature becomes MD5( '' ).
>>
>> This seems a bit counter-intuitive.  Would it make more sense for
>> get_csig() to return None until the node can actually be evaluated because
>> otherwise a missing file has the same signature as an empty file, and those
>> are two very different things.
>>
>
> It depends on usage scenario. For identification purposes it is better to
> use prefixes that will reflect additional Node statuses. This will make it
> more generic than just missing file check. The question if it is really
> what is needed?
> --
> anatoly t.
>
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