Re: [PATCH v2 1/2] tracing/events: make __string() more general

[Steven Rostedt]

On Wed, 27 May 2009, Li Zefan wrote:
> Yeah, it does look somewhat ugly..
> 
> > Could we instead perhaps add a __dynamic_array? That would take a length, 
> > and append itself to after the strings?
> > 
> 
> I thought about this actually. ;)
> 
> What troubled me is to give this new macro a better name.
> 
> We have __array() which is fixed-size, but __dynamic_array() is not
> a dynamic-size version of __array(). How about __dyn_string() or
> __dynamic_string()?

String in many languages are non fixed size. But why not call it a dynamic 
array. We can make it into a varible length array. But the assignment may 
need to be careful.

> 
> > stage 1:
> > 
> > #define __dynamic_array(item, len)	int __dyn_loc_##item;
> > 
> > stage 2:
> > 
> > #define __dynamic_array(item, len)	int item;
> > 
> > stage 3:
> > 
> > #define __get_dynamic_array(item)	\
> > 	((void *)__entry + __entry->__str_loc_##field
> > 
> > stage 4:
> > 
> > #define __dynamic_array(item, len)	\
> > 	__str_offsets.item = __str_size + \
> > 		offsetof(typeof(*entry), __str_data);	\
> > 	__str_size += len;
> > 
> 
> Then we can make __string() reuse __dynamic_array().

Yeah, the __string() can end up being a wrapper around a __dynamic_array 
macro that just adds the strlen().

-- Steve

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