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Date: Tue, 18 Feb 2014 18:26:21 +0100
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] qom: add object_property_is_set
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To: Marcel Apfelbaum <marcel.a@redhat.com>
Cc: peter.crosthwaite@xilinx.com, mst@redhat.com, qemu-devel@nongnu.org, anthony@codemonkey.ws, imammedo@redhat.com, afaerber@suse.de

Il 18/02/2014 18:11, Marcel Apfelbaum ha scritto:
> It is used to replace qemu_opt_get_bool that provides a
> parameter for a default value. In this case we need to
> differentiate "no value" from "false."

But what would the getter return in that case?  If possible, it's better 
to initialize to the default value in an instance_init method.

> I could send it with QemuMachine QOMify feature,
> but this will be a fairly large series and I *really* want
> to minimize it as much as I can, this is why I release small,
> stand-alone patches, that fixes some issue (see [Qemu-devel]
> [PATCH] qapi: output visitor crashes qemu if it encounters a NULL value),
> or adds a fairly useful feature like this one.

It depends, features are not necessarily useful without users.

Paolo