Re: nil encoding as synonym for binary encoding

In article <[e-mail]>,
  Dave Thomas <[e-mail]> writes:

>     "cat".force_encoding("binary).upcase       # => "cat"

Why the result is "cat"?

BINARY has no ASCII characters.  So 'c', 'a' and 't' is not
usable.

QUOTATION MARK is an ASCII character.  So '"' is not usable.

String#inspect returns a string which encoding is same as
self.  So inspect returns a BINARY string for a BINARY
string.

But there is no way to represent QUOTATION MARK in BINARY.

So inspect should raise an exception for BINARY string?

It is too inconvenient.

> The reason for this is that if a string is truly binary, it contains  
> bytes, not characters. There's no way of breaking it into characters,  
> so there's no way you can perform character-related operations on it.  
> (For example, it might be UTF-32, for all you know, so upcasing it  
> byte by byte would be silly). Or it might be a TCP packet, so upcasing  
> it is again meaningless. Only when you know the encoding of a sequence  
> of bits can you then treat them as characters.

Sometimes we don't distinguish ASCII and BINARY clearly.

For example, when I capture TCP packets for HTTP, I may need
case insensitive match of "GET".

Separating BINARY forces us to separate them clearly.
But the separation is not a purpose of program, I think.
-- 
Tanaka Akira