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From: Joel Brobecker <brobecker@adacore.com>
To: gdb-patches@sourceware.org
Subject: Re: [RFC] Strings and arrays without malloc
Date: Thu, 13 Mar 2008 19:22:00 -0000	[thread overview]
Message-ID: <20080313192157.GJ3738@adacore.com> (raw)
In-Reply-To: <20080309161335.GA26917@caradoc.them.org>

> Here's some things which call malloc today, and do not with the patch
> applied - yes, even the sizeof and ptype ones:

Woohoo! :)

> Here's some expressions which used to call malloc and still do; these
> are operations which involve pointers, so we need to call malloc to
> get a valid pointer for them.
> 
>   print *"abc"
>   print "abc" + 1
>   print &"abc"
>   print strcmp ("abc", "def")
>   print &{4, 5, 6}

Honestly, except maybe for the case where strcmp is involved, I find
that the semantics of the expressions could be debated. But you were
able to preserve the previous behavior, which is great.

> Here's some expressions which used to call malloc and will now produce
> an error about "value not located in memory":
> 
>   print &{4, 5, 6}[1]
>   ptype &{4, 5, 6}[1]

As per the above, I personally am not really all that much concerned
about this kind of limitation, and I agree that subscripting is more
interesting than getting the address of a subscripted element.

It's still possible to get the answer by doing a sequence of
commands instead of one convenient expression, but the following
should work, right?

    print &{4, 5, 6}
    print &(*$)[1]

Or, in one expression (if I get my precedence right):

    print &(*&{4, 5, 6})[1]

Perhaps we could add this to the documentation too.

I haven't looked at the code itself, but the benefits are really
exciting IMO.

-- 
Joel


  parent reply	other threads:[~2008-03-13 19:22 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-03-09 16:14 Daniel Jacobowitz
2008-03-09 22:20 ` Eli Zaretskii
2008-03-11  6:58 ` Tom Tromey
2008-03-13  6:12   ` Tom Tromey
2008-03-13 14:16     ` Thiago Jung Bauermann
2008-03-13 14:54       ` Tom Tromey
2008-03-13 16:22         ` Thiago Jung Bauermann
2008-03-13 16:59           ` Tom Tromey
2008-03-13 20:47             ` Tom Tromey
2008-03-13 19:22 ` Joel Brobecker [this message]
2008-03-21 15:03   ` Daniel Jacobowitz

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