On Fri, 7 Oct 2016, Nikolaus Rath wrote:
> On Oct 06 2016, Julia Lawall <[email protected]> wrote:
> >> Somehow I'm having a really hard time grasping the fundamentals. The
> >> first two examples make sense - I could adapt them for similar
> >> situations. But then, I still have absolutely no idea how I would come
> >> up with the third example, or how to adapt it. What does "idexpression"
> >> mean? What does "ptr@p1" mean? Is this documented anywhere?
> >
> > idexpression is an expression that is resricted to be an identifier. It
> > allows you to put a type on an expression that has the form of an
> > identifier. You can also say identifier x; But that is just a name. It
> > has no type. It could be an expression, a field name, a parameter name,
> > etc.
>
> Hm. Based on your last two sentences I'd conclude that 'idexpression'
> matches variable names for variables of a specific type. But that
> doesn't seem to be what you describe in your first two sentences. Could
> you explain what you meant iwth "expression that has the form of an
> identifier"?
>
> To me, an identifier is something that's written literally into the
> source code and cannot be meaningfully taken apart, e.g. a function
> name, variable name, or the member of a struct. An expression, on the
> other hand, is something that can be meaningfully split into
> sub-components. Is that also how you use these terms?
An expression is something that has a value. So an idexpression would be
something that cannot be taken apart, but it is also used in a context
where it has a value. Unlike in the case of a parameter name or field
name, where it is a name for something that will get a value in the
future.
>
> > @ connects patterns that match the same term. So match a term against the
> > explicit name ptr and also match it against an identifier expression that
> > has a particular type. This is not exactly a beginner example.
>
> Okay, I'll just ignore that for now.
>
> >> I'd hate to waste your time asking tons of such trivial questions on the
> >> mailing list, but I just can't find any helpful documentation at all...
> >
> > If you look on the web page in the papers and slides section, at the top
> > there are several tutorials and overview talks, some with video.
>
> I think I looked at everything that is not a video. But none of it
> mentioned that you can put an arbitrary name between the @@ or explained
> what the different metavariable types (idexpression, expression, etc)
> are.
The name is illustrated in Advanced SmPL:
http://coccinelle.lip6.fr/papers/cocciwk4_talk2.pdf
A variety of metavariable types are listed in slide 11 of the Linux
oriented tutorial: http://coccinelle.lip6.fr/papers/tutorial.pdf
julia
> Anyway, enough whining. Coccinelle seems like a really useful tool, even
> if I'm having an impedance mismatch with its documentation.
>
>
> Best,
> -Niko
>
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