Re: [Qemu-devel] [PATCH] trace: Allow events without arguments

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Tue, Sep 06, 2016 at 10:47:33AM +0200, Lluís Vilanova wrote:
> Stefan Hajnoczi writes:
> 
> > On Fri, Aug 26, 2016 at 11:12:47AM +0200, Lluís Vilanova wrote:
> >> Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
> >> ---
> >> scripts/tracetool/__init__.py |    5 +++++
> >> 1 file changed, 5 insertions(+)
> >> 
> >> diff --git a/scripts/tracetool/__init__.py b/scripts/tracetool/__init__.py
> >> index be24039..96657e6 100644
> >> --- a/scripts/tracetool/__init__.py
> >> +++ b/scripts/tracetool/__init__.py
> >> @@ -72,6 +72,11 @@ class Arguments:
> >> arg_str : str
> >> String describing the event arguments.
> >> """
> >> +        # check for empty argument list
> >> +        arg_str = arg_str.strip()
> >> +        if arg_str == "":
> >> +            return Arguments([])
> >> +
> 
> > Why is this necessary?  C syntax uses f(void) and not f().
> 
> > We already have trace events with no argument.  They use the correct C
> > syntax.
> 
> Sorry, I wasn't aware of that. My bad.

BTW the details of this syntax difference exists between C and C++:

In C++ foo() means foo(void).

In C you can say foo() but it means something different.  It means the
parameters are unspecified.  You can pass any arguments and the compiler
will do no type-checking!

Stefan

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