Subj : Re: Supressing errors?
To   : netscape.public.mozilla.jseng
From : Brendan Eich <brendan@meer.net>
Date : Fri Jan 30 2004 12:01 pm

Brendan Eich wrote:

> Brian Genisio wrote:
>
>> Hi all,
>>
>> I was wondering what the best way to supress specific errors are?  I 
>> can think of couple ways to do it, but none are extremely keen in my 
>> book.
>>
>> Here is where I want to supress the error:
>>
>> When a non-numeric string is passed to JS_ValueToInt32, an error is 
>> reported, and it returns false.  All I care about is that we return 
>> false.  If I get false, I will use a default value, and move on.
>
>
> Do you want JS_ValueToECMAInt32 instead?  JS_ValueToInt32 range-errors 
> if the value doesn't convert to a number, or if it converts to a 
> number that doesn't fit in a 32-bit signed int; then it rounds to 
> nearest.  JS_ValueToECMAInt32 takes non-finite (NaN, +/-Infinity) as 
> 0, then computes fmod of the number with 2^32, then truncates the fmod 
> result toward zero.
>
> The practical differences are:
>
> 1.  fmod vs. range error;
> 2.  round to nearest vs. truncation toward zero. 


Of course, JS_ValueToECMAInt32 will throw an error exception if you pass 
it a string value beginning with other than a numeric literal (possibly 
preceded by whitespace).

Why do you want to suppress errors?  Users who make mistakes, obvious or 
subtle, will be left scratching their heads.  With try/catch/finally 
exception handling in JS and ECMA for many years now, it seems to me 
much better to give the user some signal that something is amiss.

/be

.