27 May
2012
27 May
'12
12:16 a.m.
On Sat, 26 May 2012 18:03:46 -0500
"David C. Rankin" <drankinatty(a)suddenlinkmail.com> wrote:
On 05/26/2012 02:54 AM, Francois Andriot wrote:
In a word, yes—an inline declaration like that one should be valid until the end
of the scope in which it was made, just like Francois said. It doesn't matter
whether there's a chunk of code between the beginning of the scope and the
declaration.
Le 26/05/2012 01:21, David C. Rankin a écrit :
Thank you Francios,
In this case, the 'it' declared at 475 isn't unreferenced until the 475
for
loop ends at line 548. That's what makes this unclear to me. The problem I must
not be explaining correctly is this (starting line 475):
for ( TQMap<TQGuardedPtr<KMFolder>, bool>::Iterator it =
mPendingUpdates.begin();
it != mPendingUpdates.end(); ++it)
{
<snip - next line 485 (originally '::Iterator it') >
TQMap<TQGuardedPtr<KMFolder>, int>::Iterator unread_it =
mFoldersWithUnread.find(fldr);
<snip - next line 496>
int diff = unread - it.data();
<snip - next line 548 - closing for>
}
Since there are no bounding braces '{}' for the line 485 redeclaration, there
is nothing that specifically limits the scope of the 485 redeclaration. So if in
the code between 485 and 548 there were additional references to 'it.something',
how can you tell whether it is the it from the 475 declaration or the 'it' (now
unread_it) that belongs to 485 redeclaration? What if there was at say line 530
something like:
KMFolder *prev_fldr_with_unread = it.key() - jump;
Can you say that just because there was a redeclaration at 485, that the 'it'
at line 530 must be associated with with the redeclaration, even though it is
still within the code-block for the original it?
OK,
I see how that happened, but I still don't think I could have discerned
whether the 'it' at 496 went with the 'it' from 475 or the 'it'
from 485 since
it is within the code-block for TQMap<TQGuardedPtr<KMFolder>,
bool>::Iterator
it, but it is _not_ expressly in the code-block for
TQMap<TQGuardedPtr<KMFolder>, int>::Iterator unread_it
How would you know which 'it' needed to go to 'unread_it' or
'it' in this
case? When we went over it before, the way was to start with the inner-most
'it' and work out from there to separate code-blocks. That didn't work in
this
case. Any other tricks?
Hello,
in the original code, the "it" is first declared in a "for" statement
(line
475), then redeclared differently inside this "for" loop. (line 485).
Inside that loop, any "it" usage BEFORE the redeclaration (line 476 to 484)
refer the first declaration, and any "it" AFTER the redeclaration (line 486 to
end of loop) refer to the new declaration. The redeclaration implies that the
original variable is unreferenced, so it cannot be used anymore.
So, when you rename the variable of a conflicting redeclaration (this is
mandatory for GCC 4.7), you must update all references to this variable that
come AFTER the redeclaration too.
Francois