Uri Guttman <u...@stemsystems.com> writes:
> On 06/24/2013 08:46 AM, lee wrote:
>> John Delacour <johndelac...@gmail.com> writes:
>>>
>>> “Stop if it’s raining, open your umbrella.”
>>>
>>> Nobody would know what you intend to say. No condition is actually
>>> attached to “stop”.
>> last if $its_raining;
>>
>> By your logic, no condition is attached to "last". The problem with
>> perl is that it doesn't allow you to open your umbrella.
>>
>>
>
> i have been following this thread and i haven't seen a good
> explanation to you about what is really going on.
Thank you for your explanation!
> first off, last and th if modifier have nothing to do with each
> other.
Yes --- and you actually call it an "if modifier". I was merely
expecting an 'if' to be an 'if' like always. But perl has two different
'if's, the usual one and the modifying one.
> last is a just a normal builtin and the if modifier can be
> appended to any statement. why you think last behaves differently with
> if i cannot fathom.
That's not what I'm thinking. The 'last' statement was only an example
because I was trying to figure out what exactly it does, particularly
when used together with 'if'.
> the important point is that last executes immediately and any
> expressions after it will not be executed.
The 'if modifier' is executed, that is what makes a 'last if ...'
particularly confusing. It's also confusing to have two different
'if's.
> last and print "foo" ; # will never print foo.
That's very irregular, considering that there is
last if $condition; # will always execute the code after last
> print "foo" and last ; # will always print foo.
>
> both of those could be appended with an if modifier. and guess what?
> they behave the same as before IF the if condition gets met.
Yes, and the 'if' behaves differently than 'if'.
> otherwise the entire statement is skipped. the if modifier is great
> but is best used on short simple statements. complex statements
> (multiple parts with and/or/comma, etc) are best done in an if block.
Well, I find a simple statement like
print "unless\n" unless 0;
totally confusing. I have to translate 'unless' into 'if not' first.
Then I would, quite naturally, expect
unless 0 {
print "unless\n";
}
to work, but it doesn't compile. It is another irregularity that one
time you must use brackets and another time you don't need them.
When you try
unless 0 print "unless\n";
it doesn't compile, either. Where's the logic in that?
> last by itself is simple and goes well with if modifier.
>
> last if SOME_LOOP_CHECK ;
> next unless OTHER_CHECK ;
>
> those are very common and readable perl statements.
It's an inconsistency.
> as for the ternary (or conditional) operator, it is designed for its
> return value. its precedence and that of other ops works fine if it
> just returns one of two expression. when you get into assignment, the
> precedence blows up and you need parens.
That's a really good point :)
> so you can code however you want but when people look at your code
> later on they will question it and wonder why you chose the wrong
> idioms. this will affect code review, job prospects, and more. there
> are reasons both logical and social why some idioms are better than
> others. learn the reasons and your code will be better and easier to
> read and maintain.
That's another good point --- and I like it when my code looks good, no
matter whether anyone else ever sees it or not. Besides it being easier
to work with, beautiful code is very pleasing.
--
"Object-oriented programming languages aren't completely convinced that
you should be allowed to do anything with functions."
http://www.joelonsoftware.com/items/2006/08/01.html
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