Julia Lawall wrote:
> On Thu, 9 Feb 2012, Michael Stefaniuc wrote:
>
>> Hello,
>>
>> the type of an expression metavariable when passed to python is
>> <type 'instance'>
>> but an expression list gets flattened to a string aka
>> <type 'str'>
>
> Perhaps. I was hoping to get rid of the instance idea, as I don't see
> the point of having anything other than string, ast least if itis not
> going to contain any useful information.
Well, yeah it is just a wrapper object around a string. An array of
strings would be fine too for the expression list. I was thinking to do
simple regexp matches against the expression thus avoiding any parsing
of the expression. With a flat string for the whole expression I cannot
do that any longer.
>> Can the expression list be passed instead as a list/array of 'instance'?
>> That way one could get to the expressions without having to write a
>> (simplified) C parser in python.
>>
>> What I'm trying to do is to add additional checks to the Wine debug
>> functions ERR/FIXME/TRACE/WARN. Those are printf style functions with
>> varargs. While they do use __attribute__(format) there are stricter
>> checks that can be done for those. But those require the parsing of the
>> format string and thus the need to go through python.
>
> Could another option be to process the arguments individually? I'm not
> sure to understand how the __attribute__(format) fits in, but if one
> considers the normal printf, then one could write
>
> @@
> expression str,e;
> expression list[n] es;
> @@
>
> printf(str,es,e,...)
>
> Then afterwards one could inherit n, and use that to check that the
> corresponding ยค directive in str is compatible with e.
Yes, I had that initially but then I'll hit the python rule a lot more
often which from past experience can be a severe performance penalty.
Though I need to measure this to see how big the impact is.
Also I'll need to cache the parsed format string to not have to re-parse
it over and over. But that is trivial to do and I planned to do it
anyway as some format strings are very common.
thanks
bye
michael
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