Chris, On Fri, Jan 31, 2014 at 10:08 AM, Chris Snyder <chsny...@gmail.com> wrote:
> On Thu, Jan 30, 2014 at 12:12 PM, Jerry B. Altzman <jba...@altzman.com>wrote: > >> >> 'Variable variables' aren't pure evil; they just provide a level of >> indirection that allows for fine-grained loss of control at runtime. >> > > Not only are they not evil, they're necessary for a lot of Don't Repeat > Yourself optimizations. > Variable-variables as put here are not necessary in any situation. In general they are dangerous, and a potential security hole. If you MUST break down to native variables, use an array, and then extract() with the "overwrite" flag as false (to prevent potential issues). http://us2.php.net/extract > I use this pattern all the time: > > foreach( array('pages', 'posts', 'comments') AS $collection ) { > ${$collection} = $model->load( $collection ); > // do more stuff with ${$collection} here > $template->assign( ${$collection}, $collection ); > } > Yes, and that's significantly worse than: $container = array(); foreach( array('pages', 'posts', 'comments') AS $collection ) { $container[$collection] = $model->load( $collection ); // do more stuff with $container[$collection] here $template->assign( $container[$collection], $collection ); } It's even more clear, since it shows outright where the data is. You can tell instantly with any read where a variable was set. Using variable-variables, you have literally no idea until runtime (stepping through with a debugger) what area of code touches what variable. Without them (using arrays or objects) you can clearly see *what* container is being used, if not the specific element of it. It's a little bit harder to read until you get used to it, but because it's > DRY it's much easier to manage over time. > Many a great evil in programs have been done in the name of DRY. DRY != easier to manage. Clean coding with a focus on readability improve maintainability in the long term. Hacks to save a few characters of writing at the expense of cognitive load do not. In short, the only form of variable-variables that I believe should **ever** be used are variable object property/method references: $obj->$property = blah; $obj->$method(); Any other usage is simply mis-using variables where you should use a more appropriate data structure (like an array or object)... Anthony > _______________________________________________ > New York PHP User Group Community Talk Mailing List > http://lists.nyphp.org/mailman/listinfo/talk > > http://www.nyphp.org/show-participation >
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