Re: Define python hooks

[nojhan <nojhan at nojhan dot net>]

Here are the three complete examples, I hope this will be more clear.

Or in a gist:
https://gist.github.com/nojhan/c3bc28e2fa0608f21551

-- 
nojhan


On Wed, Oct 29, 2014 at 7:39 PM, Doug Evans <xdje42@gmail.com> wrote:
> On Tue, Oct 28, 2014 at 6:17 AM, nojhan <nojhan@nojhan.net> wrote:
>> The documentation states that "It is valid for a hook to call the
>> command which it hooks. If this occurs, the hook is not re-executed,
>> thereby avoiding infinite recursion."
>> But this does not seems to be true for the python API.
>>
>> Here what I tried:
>> 1) Defining the hook as a python function that would gdb.execute the
>> same command. Failed, because then the command is executed twice.
>
> You mean the hook is executed twice, right?
> The docs say the hook won't be executed twice, but executing the
> command twice is ok.
>
> I tried a trivial example and couldn't reproduce symptoms of the hook
> being executed twice.
> This is with current sources and 7.8 (release and branch).
>
> (gdb) define foo
> echo Hi there.\n
> end
> (gdb) define hookpost-foo
> echo Me again.\n
> python gdb.execute("foo")
> end
> (gdb) foo
> Hi there.
> Me again.
> Hi there.
> (gdb)
>
>> Additionally, I did not find how to access the arguments of the
>> command.
>
> I'm not sure what you mean here.
> Access the arguments of the command from the hook?
> I don't think we support that.
>
>> 2) Overload the existing command with a python class binded on the
>> same command name. Failed because of infinite recursion.
>
> Infinite recursion because command -> hook -> command -> hook -> ...
> or something else?
> Just trying to understand if and how this is different from (1).
>
> If it's easy, providing an example so that we can see it for ourselves
> will help.
>
>> 3) Use a named pipe to communicate. Failed (sort of) because one
>> should sleep a variable amount of time waiting for the pipe to be
>> consumed before returning to the prompt.
>
> I don't understand how this relates to (1) and (2).
> Communicate what between whom?

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