From: matz@... (Yukihiro Matsumoto)
Date: 2001-08-02T03:28:46+09:00
Subject: [ruby-talk:18988] Re: "Bang" versions of numerical methods on non-immediate values [was: Numbers classes.. Rational number? ]

Hi,

In message "[ruby-talk:18977] "Bang" versions of numerical methods on non-immediate values [was: Numbers classes.. Rational number? ]"
    on 01/08/02, Kent Dahl <kentda@stud.ntnu.no> writes:

|Summary: I want methods add!, sub!, div! and mul! for all numeric
|objects.

immediate values (fixnums and symbols) cannot be modified from method,
so you cannot implement any bang method for fixnums.  You need
assignment to alter value in a variable.

You want

|	a = b = 1
|	a.add!(1)	# a==2 and b==1, due to immediate values

but since 1 is a fixnum, thus the value of a cannot be changed.
Considering this fact and that fixnums are most common numeric, bang
method for numeric is not a good idea.

							matz.