Re: [Firebird-devel] Exceptions with custom message text

[Mike N. <ta...@al...>]

Alex Peshkov wrote:

> This syntax with string-only substitution sounds good for me.
> Must we enable exceptions like:
> FOO='Hey {3}, you can't {1} record #{3}!'
> Should we treat this as a bug or:
> 'Hey Mike, you can't delete record #Mike!'

The latter. Even if perhaps a bit odd to not use parameter 2 in this
example, I don't see why reusing parameters like this would be a
problem.

> Should we require precise match for number of exception params
> and {n} in exception or may replace missing one with empty strings
> and ignore unneeded?

I think parameters that are requested in format string but not present
at the point of use (i.e. the exception clause) should be allowed, at
least we shouldn't SEGV. :-)

What such missing parameter should be replaced with, I do not know. An
empty string is one possibility, but perhaps the string "{missing
exception parameter n}", where 'n' would be the parameter number
expected, such as "{3}". I'd also expect that string to be hard-coded
and not subject to localisation.

What could pose another problem, maybe even more interesting, would be
to give too many parameters. What should the outcome of that be? I
believe it should do substitution as requested, but maybe display even
the error? Something like:

Hey nn, ... (the real message)
Too many parameters to exception FOO from SP BARF. Expected 3 but got 6
parameters.
param4: "Symphony of destruction"
param5: "3.1415926535897932384626433832795"
param6: "80:4711"

The "from SP BARF" might or might not be a good thing to have, to help
in tracking down such offenders.


But this is still all an academic discussion, right? :-)

/Mike