Re: [Qemu-devel] [PATCH 02/14] qlit: move qlit from check-qjson to qobject/

[Markus Armbruster]

Eduardo Habkost <address@hidden> writes:

> On Thu, Aug 24, 2017 at 12:33:38PM +0200, Marc-André Lureau wrote:
>> Fix code style issues while at it, to please check-patch.
>> 
>> Signed-off-by: Marc-André Lureau <address@hidden>
>> ---
>>  include/qapi/qmp/qlit.h | 49 +++++++++++++++++++++++++
>>  qobject/qlit.c          | 89 +++++++++++++++++++++++++++++++++++++++++++++
>>  tests/check-qjson.c     | 96 
>> +------------------------------------------------
>>  qobject/Makefile.objs   |  2 +-
>>  4 files changed, 140 insertions(+), 96 deletions(-)
>>  create mode 100644 include/qapi/qmp/qlit.h
>>  create mode 100644 qobject/qlit.c
>> 
>> diff --git a/include/qapi/qmp/qlit.h b/include/qapi/qmp/qlit.h
>> new file mode 100644
>> index 0000000000..4e2e760ef1
>> --- /dev/null
>> +++ b/include/qapi/qmp/qlit.h
>> @@ -0,0 +1,49 @@
>> +/*
>> + * Copyright IBM, Corp. 2009
>> + * Copyright (c) 2013, 2015, 2017 Red Hat Inc.
>> + *
>> + * Authors:
>> + *  Anthony Liguori   <address@hidden>
>> + *  Markus Armbruster <address@hidden>
>> + *  Marc-André Lureau <address@hidden>
>> + *
>> + * This work is licensed under the terms of the GNU LGPL, version 2.1 or 
>> later.
>> + * See the COPYING.LIB file in the top-level directory.
>> + *
>> + */
>> +#ifndef QLIT_H_
>> +#define QLIT_H_
>> +
>> +#include "qapi-types.h"
>> +#include "qobject.h"
>> +
>> +typedef struct LiteralQDictEntry LiteralQDictEntry;
>> +typedef struct LiteralQObject LiteralQObject;
>> +
>> +struct LiteralQObject {
>> +    int type;
>> +    union {
>> +        int64_t qnum;
>> +        const char *qstr;
>> +        LiteralQDictEntry *qdict;
>> +        LiteralQObject *qlist;
>> +    } value;
>> +};
>> +
>> +struct LiteralQDictEntry {
>> +    const char *key;
>> +    LiteralQObject value;
>> +};
>> +
>> +#define QLIT_QNUM(val) \
>> +    (LiteralQObject){.type = QTYPE_QNUM, .value.qnum = (val)}
>> +#define QLIT_QSTR(val) \
>> +    (LiteralQObject){.type = QTYPE_QSTRING, .value.qstr = (val)}
>> +#define QLIT_QDICT(val) \
>> +    (LiteralQObject){.type = QTYPE_QDICT, .value.qdict = (val)}
>> +#define QLIT_QLIST(val) \
>> +    (LiteralQObject){.type = QTYPE_QLIST, .value.qlist = (val)}
>
> I'm still trying to understand why this exists.  Doesn't this
> provide exactly the same functionality as QObject?

The value-add is initializers.  Check out check-qjson.c for examples.

Use cases:

* Specify expected output as data (QLitObject initializer), then use
  qlit_equal_qobject() to verify actual output matches.  Example:
  check-qjson.c.  I think it compares nicely to the qdict_get morass we
  use elsewhere.

* Specify a QObject as data (QLitObject initializer), build it with
  qobject_from_qlit().  Example: PATCH 14.  I think it beats specifying
  the QObject in code (qdict_new(), qdict_put(), ...) at least when the
  QObject is big.