The Right Approach to Exceptions

Jacob Carlborg doob at
Tue Feb 21 00:12:28 PST 2012

On 2012-02-20 21:25, Nick Sabalausky wrote:
> "H. S. Teoh"<hsteoh at>  wrote in message
> news:mailman.704.1329767254.20196.digitalmars-d at
>> On Mon, Feb 20, 2012 at 08:36:56PM +0100, Andrej Mitrovic wrote:
>>> On 2/20/12, Juan Manuel Cabo<juanmanuel.cabo at>  wrote:
>>>> will be trouble. Instead please do:
>>>>          "The '%1$s' file's size is %2$d which is wrong"
>>> That is the shittiest formatting specifier ever invented. The
>>> unreadability of it is why I never, ever, use it. Python solved this
>>> nicely with its {0} {1} syntax:
>>>>>> print '{0} and {1}'.format('foo', 'bar')
>> Actually, even that isn't ideal. How is the translator to know what on
>> earth {0} and {1} are? Sometimes you need to know in order to make a
>> good translation. This would be even better:
>> "The ${file}'s size is ${size}, which is wrong"
>> The usefulness of named arguments is even more apparent in complex
>> message like this one:
>> "${file}:${line}: Expecting ${expectedtoken}, got ${inputtoken}"
>> Without named parameters, you'd have:
>> "{0}:{1}: expecting {2}, got {3}"
>> which is almost impossible to translate. What are {0} and {1}? What are
>> {2} and {3}? Does it mean "12:30pm: expecting program to succeed, got
>> general protection fault"?
>> Using named parameters makes it clear this is a parser error, not
>> something else. This difference may mean using a completely different
>> grammatical structure to translate the message.
> vote++; I've been drooling over the idea of named argument format strings in
> D for a long while.
> I also agree with posix-style specifiers being barely readable. I fell in
> love with C#'s "Hello {1}" style at first sight, and was thrilled that Tango
> adopted it. Then I moved to Phobos2, and have been missing those wonderful
> curly braces ever since.

Tango doesn't even require you put a number in the parameter, just 
"Hello {}". It is still possible to put a number if you want, something 
like this "Hello {2} {1} {1}".

/Jacob Carlborg

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