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Re: conditional statements in list constructorsby kcott (Archbishop) |
on Mar 27, 2014 at 14:48 UTC ( [id://1079937]=note: print w/replies, xml ) | Need Help?? |
G'day Don Coyote, if may be used as a Compound Statement or as a Statement Modifier. It is not an operator. Placing an if statement in a do block, as you show, can emulate the ternary operator but, as is fairly obvious, results in clunky code with poor readability and maintainability. So, if introduces a compound statement (or statement modifier) and ?: is an operator. They are not synonymous. With do blocks, parentheses, and other syntactical tricks, you can usually (if not always) replace one with the other; however, this is typically not a good idea. [For more on this, see "Re: Code blocks with ternary operator or trailing conditionals", which I wrote a few weeks ago.] The ternary operator can be used in any list, not just to generate an array, so an improvement on the print examples you show, might be (using equivalent code):
Although, perhaps a more likely scenario might be something like:
When using the ternary operator, take care with precedence issues and add parentheses where needed (the documentation shows some examples). A final point, unrelated to conditionals, regarding your test:
Taking a reference to a list actually returns a list of references to each item in the original list. Accordingly, it would probably be a good idea to avoid any instances of:
While that may work when first written using a list with only one item, any subsequent modifications which result in additional list items will cause problems. A better option would be:
Item 2. of "perlref: Making References" has more information on this. -- Ken
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