Re: Conversion of types

On 14 Jul 2004, at 22:50, Dion Almaer wrote:
> Hi -
>
> What do you guys think about smart conversion of types in situations?
>
> E.g. compare a Perl script to a Groovy one:
>
> Perl
>
> ---------------------------------------------------
> #!/usr/local/bin/perl
>
> my $amount = "1";
>
> if ($amount < 2) {
>         print "Amount is less than two\n";
> }
> ---------------------------------------------------
>
> (this will print 'Amount is less than two')
>
> ---------------------------------------------------
> amount = "1";
>
> if (amount < 2) {
>         println "Amount is less than two";
> }
> ---------------------------------------------------
>
> (this won't work)
>
> What are peoples thoughts on this?

I'm a little worried about 'clever' auto-type coercion, especially when 
using strings and numbers. Often Java methods return an int/Integer 
meaning a 'character' and so comparisons/operations are meant to coerce 
an int into a Character.

e.g. many of the stream methods return type 'int' for a character.

String text = "f"
Reader r = ...
int ch = reader.read()
if (text == ch) {
     ...
}

In the above we are coercing things into a Character and performing 
comparisons.

This would seem to conflict with treating ch as a number.

So to avoid confusion I think I prefer explicit coercion of strings to 
numbers. Also remember, numbers as a string are frequently 
locale-dependent - so we often need to know which locale to use.

e.g.

// use JVM default
"1,200".toNumber()

// use specific locale
"1,200".toNumber(myLocale)

James
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