Re: Exception Specification Compromise
A compiler *could* offer the static checking of no-throw functions as
an extension, but you will very quickly run into practical problems.
For example, should the compiler, with the feature enabled, complain
about this function:
void write_to_log(char* text) throw()
{
FILE* logfile = fopen("/var/log/mylogs", "a");
fprintf(logfile, "%s", text);
fclose(logfile);
}
None of the functions used here have a no-throw specification, so the
compiler must assume they can throw an exception (unless the compiler
has special knowledge about these functions, but then just substitute
simple wrappers from an internal, company-specific library).
You're right, but the solution is actually quite simple. Either you just
keep your function as it probably looks today, without throw(), as below.
void write_to_log(char* text)
{
FILE* logfile = fopen("/var/log/mylogs", "a");
fprintf(logfile, "%s", text);
fclose(logfile);
}
Or you explain to the compiler that this is indeed a no-throw function
using throw() and try/catch(...) as below.
void write_to_log(char* text) throw()
{
try
{
FILE* logfile = fopen("/var/log/mylogs", "a");
fprintf(logfile, "%s", text);
fclose(logfile);
}
catch(...) {}
}
The only way around that is to change the declaration of *every*
function that is known not to throw any exceptions, which is a
prohibitive amount of work.
I realize that we probably can't change existing libraries, but if we
could have an optional static check on no-throw functions, i.e. declared
throw(), it would be a start of an opening for better exception safety
without affecting those who don't want or aren't able to use it.
{excess quoting deleted --mod}
Bart v Ingen Schenau
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