adding a watch expression

[amiracam]

HI, today I noticed one can add a "watch" expression , something which I was doing during a live debug session, which it thought pretty cool , well for Ruby circles, but some expressions I could add and some I could not. So I wonder what the rules are or is it also that some expressions you can not add during a live debug session.

To be clear I was in a debug session and I highlighted , popped mouse and clicked on "add watch" e.g.


      File.directory?(mypath)   false   False

which is fine

but:

      processfiles(mypath)   undefined local variable or method   

is not fine

note that both rely on the mypath local scope var

now, not a biggie problem per se, I can live with trial and error for a bit, however I am curious as to what the tools underlying rules are in this situation.

thanks

[Huw Collingbourne]

Which version of Ruby In Steel is this (1 or 2 and, if the latter, beta 1 or beta 2)?

Huw

[amiracam]

Ris 2 beta 2
ruby 1.92
same as I was using for Ris 2 beta 1

[Dermot]

There's no special rules for the watch window. The debugger just uses Ruby to 'eval' the expression in the stack frame where the debugger is halted. If Ruby can successfully evaluate the expression, the result is displayed. If not an error message is given. So it's down to the interpreter, really.

There are some very tricky problems to deal with concerning Ruby 'inspectors' (these are user written routines return the result for more complicated types), but probably won't come across these in simple examples.

Dermot