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[Bug translator/5219] printd and printdln broken
- From: "hunt at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sources dot redhat dot com
- Date: 25 Oct 2007 20:41:05 -0000
- Subject: [Bug translator/5219] printd and printdln broken
- References: <20071025184143.5219.hunt@redhat.com>
- Reply-to: sourceware-bugzilla at sourceware dot org
------- Additional Comments From hunt at redhat dot com 2007-10-25 20:41 -------
Subject: Re: printd and printdln broken
On Thu, 2007-10-25 at 19:39 +0000, joshua dot i dot stone at intel dot
com wrote:
> ------- Additional Comments From joshua dot i dot stone at intel dot com 2007-10-25 19:39 -------
> (In reply to comment #0)
> > printd[ln] cannot take a string variable as the first argument.
> > probe begin {
> > b = ","
> > printd(b,"foo","bar")
> > println("")
> > exit()
> > }
>
> Currently a call like printd(",", "foo", 42, "bar") gets synthesized into
> _stp_printf("%s,%d,%s", "foo", 42, "bar"). Using non-literal delimiters, would
> have to be instead:
> _stp_printf("%s%s%d%s%s", "foo", delim, 42, delim, "bar")
That looks fine to me.
> Perhaps we could still optimize the literal case though.
Why bother? I timed the above examples and measured their speed as
identical within a few percent.
Of course, if everything was a literal, we could do some serious
optimization, but that case will likely never happen in real life.
> Do you really see a need to have non-literal delimiters?
It came up in some code I was writing, the first time I ever used
printd. What about examples where you might want to specify the
delimiter on the command line. I think it is also bad to have hidden
requirements that some strings need be literals.
>
> > Also printd[ln] cannot handle case where there is only one values to print:
>
> This is consistent with the documentation, which specifies "two or more values."
OK then. Forget that part.
Martin
--
http://sourceware.org/bugzilla/show_bug.cgi?id=5219
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