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Re: [Qemu-devel] [PATCH v6 01/15] qapi: add 'if' to top-level expression
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [PATCH v6 01/15] qapi: add 'if' to top-level expressions |
Date: |
Thu, 28 Jun 2018 16:57:26 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) |
Marc-André Lureau <address@hidden> writes:
> Accept 'if' key in top-level elements, accepted as string or list of
> string type. The following patches will modify the test visitor to
> check the value is correctly saved, and generate #if/#endif code (as a
> single #if/endif line or a series for a list).
>
> Example of 'if' key:
> { 'struct': 'TestIfStruct', 'data': { 'foo': 'int' },
> 'if': 'defined(TEST_IF_STRUCT)' }
>
> The generated code is for now *unconditional*. Later patches generate
> the conditionals.
>
> A following patch for qapi-code-gen.txt will provide more complete
> documentation for 'if' usage.
This paragraph looks obsolete now, because...
> Signed-off-by: Marc-André Lureau <address@hidden>
> Reviewed-by: Markus Armbruster <address@hidden>
> ---
> scripts/qapi/common.py | 35 ++++++++++++++++++++----
> tests/test-qmp-cmds.c | 6 ++++
> docs/devel/qapi-code-gen.txt | 22 +++++++++++++++
... you update documentation right in this patch (I like that).
[...]
> diff --git a/docs/devel/qapi-code-gen.txt b/docs/devel/qapi-code-gen.txt
> index 88a70e4d45..7af60b48f3 100644
> --- a/docs/devel/qapi-code-gen.txt
> +++ b/docs/devel/qapi-code-gen.txt
> @@ -739,6 +739,28 @@ Example: Red Hat, Inc. controls redhat.com, and may
> therefore add a
> downstream command __com.redhat_drive-mirror.
>
>
> +=== Configuring the schema ===
> +
> +Top-level QAPI expressions.
This sentence no verb :) I suspect an editing accident ate "can take an
'if' key".
> The value must be a string or a list of
> +string.
s/string/strings/
> The corresponding generated code will then guard the inclusion
> +of that member in the larger struct or function with #if IFCOND
> +(or several #if lines for a list), where IFCOND is the value of the
> +'if' key.
"that member" makes little sense; top-level expressions aren't members.
> +
> +'struct', 'enum', 'union', 'alternate', 'command' and 'event'
> +top-level QAPI expressions can take an 'if' keyword like:
> +
> +{ 'struct': 'IfStruct', 'data': { 'foo': 'int' },
> + 'if': 'defined(IFCOND)' }
Repetitive.
Moreover, I'd like to see the example spell out how conditions affect
generated code.
Here's my try:
=== Configuring the schema ===
The 'struct', 'enum', 'union', 'alternate', 'command' and 'event'
top-level expressions can take an 'if' key. Its value must be a string
or a list of strings. A string is shorthand for a list containing just
that string. The code generated for the top-level expression will then
be guarded by #if COND for each COND in the list.
Example: a conditional struct
{ 'struct': 'IfStruct', 'data': { 'foo': 'int' },
'if': ['defined(CONFIG_FOO)', 'defined(HAVE_BAR)'] }
gets its generated code guarded like this:
#if defined(CONFIG_FOO)
#if defined(HAVE_BAR)
... generated code ...
#endif /* defined(HAVE_BAR) */
#endif /* defined(CONFIG_FOO) */
> +
> +Please note that you are responsible to ensure that the C code will
> +compile with an arbitrary combination of conditions, since the
> +generators are unable to check it at this point.
> +
> +The presence of 'if' keys in the schema is reflected through to the
> +introspection output depending on the build configuration.
> +
> +
> == Client JSON Protocol introspection ==
>
> Clients of a Client JSON Protocol commonly need to figure out what
[...]
I'm happy to apply these proposals without a respin, if you like them.
- [Qemu-devel] [PATCH v6 00/15] qapi: add #if pre-processor conditions to generated code (part 1), Marc-André Lureau, 2018/06/27
- [Qemu-devel] [PATCH v6 01/15] qapi: add 'if' to top-level expressions, Marc-André Lureau, 2018/06/27
- Re: [Qemu-devel] [PATCH v6 01/15] qapi: add 'if' to top-level expressions,
Markus Armbruster <=
- [Qemu-devel] [PATCH v6 02/15] tests, Marc-André Lureau, 2018/06/27
- [Qemu-devel] [PATCH v6 03/15] qapi: pass 'if' condition into QAPISchemaEntity objects, Marc-André Lureau, 2018/06/27
- [Qemu-devel] [PATCH v6 04/15] qapi: leave the ifcond attribute undefined until check(), Marc-André Lureau, 2018/06/27
- [Qemu-devel] [PATCH v6 06/15] qapi: mcgen() shouldn't indent # lines, Marc-André Lureau, 2018/06/27
- [Qemu-devel] [PATCH v6 05/15] qapi: add 'ifcond' to visitor methods, Marc-André Lureau, 2018/06/27