Re: The explanation of order-only prerequisites is not clear

[Paul Smith]

Please don't top-post on technical mailing lists.  Thanks.

I recommend that you change the way you create your requests as follows:
first, create the message you want to send.  As we can all see, you're
very frustrated and your messages are, to be blunt, rude and impolite.

Then, once you've written your message and expressed your frustration,
you should save that message for an hour or so without sending it.
Then, once you've calmed down, go back and edit your message and remove
all the parts that are unspecific, accusatory, and demanding, and leave
just those parts that are honest requests for help and explanations, and
those parts which are reporting straightforward errors.  Send that
message instead.

Believe me, I've rewritten almost every reply I've made to your posts,
some more than once.


On Wed, 2010-09-08 at 08:36 +0430, ali hagigat wrote:
> The section of order-only prerequisites does not explain the function
> of this sort of prerequisite well in my opinion. After one sentence ,
> it starts several lines about how to specify an order-only
> prerequisite by pipe symbol and so on(only it insists on syntax
> issue).

I don't see how you can say that since I quoted a long explanatory
section over three paragraphs, and nowhere in there does it talk about
pipe symbols at all, much less concentrate only on syntax.

Did you actually read the section I quoted?

Perhaps if you go through that section and read it slowly and carefully
and try to understand each sentence, then come back and explain which
parts did not make sense, we can improve it.

> 1) If I specify  an order-only prerequisite, will be evaluated sooner
> than other normal prerequisites?

No.  Why would it?

> 2) Instead of "target to be updated" you could say, the command or
> recipe of the target which is to be executed" as follows:
> 
> If a target has an order-only prerequisite and that order-only
> prerequisite is a file(or directory) and it is updated(because it may
> be the target of some other rule itself), the command or recipe of
> that target will not be executed.
> Did i understand the purpose of the order-only prerequisite?
> Is my sentence more clear than the manual?!!

First, this is not more clear than the manual.  For one small example,
you say "if ... [the] order-only prerequisite is a file (or directory)".
That implies it might NOT be a file or directory.  What's the
alternative?  And what happens in that case?

Second, it's flat-out wrong.  If an order-only prerequisite is updated
that doesn't mean that the recipe of the target will not run: that would
be silly.  Order-only prereqs are not some kind of "exclusive
or" (either one or the other but not both), which is what your text here
says.

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