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Peter Lynch wrote:
> Hi
>  I am still a beginner at Ruby, and have just arrived at this in my 
> learning curve.
> 
>  I would like to code
>      not(condition1) && not(condition2)
>  This is accepted in irb -
>      not(condition1) && condition2
>  but this produces a syntax error
>      condition1 && not(condition2)
> 
>  I do not get it (obviously). I do not even know what to ask in reply -How do I code a compound condition, without introducing extra wrappers 
> like -
>      (not(condition1)) && (not(condition2))
> 
>  Regards
>  Peter
> 
> 
> 

For compound conditions, I'd use ! instead of not, likewise && and ||
instead of and and or. With copious parentheses. I prefer the word
variants when the result would read like a sentence - with compound
booleans all hope is lost anyway, and I prefer to be able to tell terms
apart from operators easier (one being letters, the other special
characters).

Also, due to the low binding of not, I prefer to use "unless" and
"until" instead of "if not" and "while not".

Also, I think the (!(condition1) && !(condition2)) is slightly bad form.
Inverting the logic makes things simpler to read: (condition1 ||
condition2). Yay freshman discrete maths. (Although I admit to cheating,
I fired up IDEA to tell me this.)

David


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