Re: When operator>> can throw...
Erik WikstrFm <Erik-wikstrom@telia.com> wrote:
On 2008-01-19 16:15, Daniel T. wrote:
This is basically what I have now...
class Foo { /* definition irrelevant */ };
istream& operator>>( istream& is, Foo& foo ); // could throw
int main() {
ifstream file( "file.txt" );
Foo foo;
int i = 0;
try {
while ( file >> foo ) {
//process foo;
++i;
}
}
catch ( exception& e ) {
cout << "error at: " << i << '\n';
}
}
The problem I'm having is that op>> could throw. If it does, I don't
want to process the foo object that threw, but I want the program to
report an error and continue extracting foo objects.
I could make op>> a no-throw and give Foo some sort of error or invalid
state, but that doesn't feel right. I can't report the error inside the
op>> because I don't have enough information to make a full report.
Does anyone have a better idea, or do I give Foo and error state and
query it after the read?
Something like this perhaps?
int main() {
ifstream file( "file.txt" );
Foo foo;
int i = 0;
while ( file.eof() == false ) {
try {
file >> foo;
} catch ( exception& e )
cout << "error at: " << i << '\n';
continue;
}
++i;
}
}
That doesn't handle the end of file correctly...
I could do something like:
typedef int Foo;
int main() {
ifstream file( "file.txt" );
Foo foo;
int i = 0;
while ( file.eof() == false ) {
try {
while ( file >> foo ) {
// process foo
++i;
}
} catch ( exception& e ) {
cout << "error at: " << i << '\n';
}
}
}
But that seems strange.
Does anyone have a different idea?
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