[ruby-core:23446] Some expect.rb miprovements

Hello,

I was using expect.rb to substitute expect command (as I'm not in a mood to
learn Tcl). However, it demands some attention.

I took expect(1) command as a idea, but not a rule, of how expect should
behave.

First, a little bug that incorrect pattern classes are not treated
correctly. It would result in a "e_pat unspecified" which gives no clues of
what happened. Now I raise an exception. I let the another one parameter,
timeout, unchecked cause the error messagem like "String can't be coerced
into Fixnum" would give a good hint of what is wrong.

I changed pat and e_pat to pattern to meet some other similar parameter
references.

Back to the timeout parameter, timeout was not a global timeout but a single
char timeout. If the io keeps giving input, it never stops. For example:
While using expect.rb to interact with a dlink switch telnet, if it
generates any log information on the terminal (as it does constantly like
"link down") before the timeout time, even if my expression never occurs,
the timeout is never over. I changed this to use timeout as a global timeout
as expect command does.

Keeping on timeout stuff, if it read some input and times out, where this
buffer goes? In expect.rb, it is just lost. For the expect command, this
buffer can be used in the next matching. I use a instance variable to keep
and reuse the unused buffer on the next expect call.

I changed the default timeout value to meet the expect command default one.
If someone really wants to use 9999999 seconds, just go ahead ans specify it
on parameters. However, interactive scripts generally deal with unexpected
behaviors. 30s, as expect command uses, seems to be reasonable.

I also added some documentation that was missing.

This is my first patch sent to ruby. I should submit this to
redmine.ruby-lang.org, isn't it? But which version? Contribution
documentation seems to be a litte disperse.

Cheers,

---
    Luiz Angelo Daros de Luca, Me.
           [e-mail]