From: sto.mar@...
Date: 2013-01-12T01:34:18+09:00
Subject: Re: Best practice for &&, ||, and, or

Am 05.01.2013 13:35, schrieb sto.mar@web.de:
> Hi group,
>
> I really would be interested in your thoughts about this
>
>    a. in the context of your own projects, and
>    b. with regard to teaching programming newbies
>
> The GitHub Ruby Styleguide [1] states: "The and and or keywords are
> banned. It's just not worth it. Always use && and || instead".

Thanks to all for your interesting input.

To sum up: I have come to the conclusion to ban 'and'/'or' completely
from my teaching (except for mentioning their existence).
In the limited time I have I can only discuss a small subset
of the Ruby language anyway, and flow control with 'and'/'or'
rather falls in the category of syntactic sugar, especially for
a beginner.

I have been confirmed in the believe that 'and'/'or' for logical
expressions -- though very readable -- is just BAD and dangerous,
because the behavior is too surprising.
A student (and maybe not only a student) might happily refactor

   if cond1 and cond2
     ...
   end

to

   condition = cond1 and cond2
   if condition
     ...
   end

without ever noticing that this would break the logic of the code.

I still might use 'and'/'or' for flow control in my personal projects,
but I use this idiom very seldom anyway and rather prefer if/unless.

Regards,
Marcus


> So what's your practice/recommendation:
>
>    1. use only &&, ||
>    2. use only `and', `or'
>    3. distinguish between boolean expressions (if this && that)
>       and control flow (loot = give_money  or die)
>    4. ???
>
> 1. and 2. might require extra parentheses that often could be
> avoided with 3., but using parentheses might be clearer anyway.
> Especially for students who might have a hard time coping with
> the different precedences.
>
> I tend to 1., and for own projects maybe to 3.
>
> Regards,
> Marcus
>
>
> [1] https://github.com/styleguide/ruby/

-- 
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