From: eden li <eden.li@...>
Date: 2007-03-11T22:59:07+09:00
Subject: Re: string to int: ruby documentation?

irb(main):036:0> Class.constants.map { |c| eval(c).new rescue
nil }.compact.map { |s| Integer(s) rescue $! }.select { |c| c.is_a?
(Exception) }.map { |c| c.class }.uniq
=> [TypeError, ArgumentError, NoMethodError]

Looks like it could TypeError and NoMethodError as well...

On Mar 11, 8:40 pm, 7stud 7stud <dol...@excite.com> wrote:
> Hi,
>
> In trying to convert a string to an integer, I found this passage in the
> ruby documentation:http://dev.rubycentral.com/ref/
>
> -------------
> str.to_i -> anInteger
>
> Returns the result of interpreting leading characters in str as a
> decimal integer. Extraneous characters past the end of a valid number
> are ignored. If there is not a valid number at the start of str, 0 is
> returned. The method never raises an exception.
> -------------
>
> That description seems complete.  It talks about edge cases, and what
> happens, and that the method doesn't throw an exception.  Then I found
> this passage:
>
> -----------
> Integer( arg ) -> anInteger
>
> Converts arg to a Fixnum or Bignum. Numeric types are converted directly
> (with floating point numbers being truncated). If arg is a String,
> leading radix indicators (0, 0b, and 0x) are honored. This behavior is
> different from that of String#to_i.
> ------------
>
> In that description, there is no mention of exceptions that can be
> thrown, but when I try the Integer() method, this is the output:
>
> irb(main):002:0> Integer("10")
> => 10
> irb(main):003:0> Integer("10abc")
> ArgumentError: invalid value for Integer: "10abc"
>         from (irb):3:in `Integer'
>         from (irb):3
> irb(main):004:0> Integer("hello")
> ArgumentError: invalid value for Integer: "hello"
>         from (irb):4:in `Integer'
>         from (irb):4
> irb(main):005:0>
>
> So, it seems pretty clear that the Integer() method can throw an
> ArgumentError exception, and I'm wondering why the docs don't mention
> what exceptions Integer() throws?  Is that typical of the docs?  If it
> doesn't say "no exceptions are thrown", should I assume it can throw
> some as yet unidentified exception?
>
> --
> Posted viahttp://www.ruby-forum.com/.