From: Adiel Mittmann <adiel@...>
Date: 2011-03-17T06:28:38+09:00
Subject: Re: NoMethodError#message takes very long

Hi, I discovered what's causing the problem.

Ruby's function name_err_mesg_to_str (file error.c, line 929, SVN snapshot),
which produces the dreaded message, proceeds as follows:

1. It converts the object that does not possess the method in question to a
string, by calling #inspect;

2. If it doesn't like that string (i.e., if it's nil or is bigger than 65
characters), then it creates a simpler representation and use it instead.

In other words, if you happen to call a method on an object that doesn't define
to_s but that does contain a lot of data, then calling an undefined method and
trying to print the resulting exception's message will take a long time because
all the data in the object will have to be converted to a string -- just to be
discarded.

Maybe in a case like this the message should always return the simpler
representation of the object instead of calling to_s?

-- 
Adiel Mittmann