Re: [PATCH] perf: Make printing table easily

[Hitoshi Mitake]

On 03/17/10 16:50, Hitoshi Mitake wrote:
> On 03/11/10 23:06, Arnaldo Carvalho de Melo wrote:
>  > Em Thu, Mar 11, 2010 at 01:51:26PM +0100, Ingo Molnar escreveu:
>  >>
>  >> * Hitoshi Mitake<mitake@xxxxxxxxxxxxxxxxxxxxx> wrote:
>  >>
>  >>> Hi,
>  >>>
>  >>> Making table of matrix by printf is painful work,
>  >>> but it can be found in perf here and there.
>  >>> So I'd like to propose semi-automation of making table.
>  >>> New files util/table.c provides stuffs for easy table printing.
>  >>
>  >> Looks quite reasonable in theory. I suspect it would be useful to
> see a few
>  >> table printing places converted to this facility, to see the
> simplification
>  >> factor in practice.
>  >
>  > I'm going thru the printing routines now to get them usable by 
TUI/GUIs,
>  > starting with a libnewt based browser integrating initially report and
>  > annotate, after I get the first patch in shape for merging I'll 
revisit
>  > this table class of yours :-)
>
> Thanks Arnaldo!
>
> But I noticed fatal weak point of table.c.
>
> User of table.c can reduce the cost of specifying
> format specifier for printf, but like this case:
>
> table_add_fixed(t, "%p", SIZE_OF_ADDR);
> if (some_cond1)
> table_add_fixed(t, "%10d", sizeof(int));
> if (some_cond2)
> table_add_string(t, "%30s", 30);
>
> table_printf() may produces a lot of if-branch like this:
>
> if (some_cond1 && some_cond2)
> table_printf(t, table_test, 2501, "one");
> else if (!some_cond1 && some_cond2)
> table_printf(t, table_test, "one");
> else if (some_cond1 && !some_cond2)
> table_printf(t, table_test, 2501);
>
> It is not so good, as Ingo told, at least table of this style
> is not useful in real world...
>
> But, how about this style?
>
> First, user declare column with name like this:
> table_add_column(t, "num1", "%10d", sizeof(int));
>
> Then, user can add values with name,
> table_add_field(t, "num1", 2501);
>
> Finally, flush stored column
> table_flush_line(t);
>

Another suggestion:
If table_add_column() returns "column ID",
table_add_field() can specify tha column with it
and duplication of string can be reduced.
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