The feature set remains in flux, but continued speed improvement remains a critical goal, according to Zeev Suraski, CTO of Zend, which has led development of the engine for PHP. "We're continuing to work on performance, although we won't be seeing anything nearly as dramatic as what we've seen in 7.0."
There are a lot of syntax-level RFCs (Request for Comments) in a discussion phase pertaining to proposed features, but it's not yet clear which ones will be accepted, Zuaraski said.
Features due in PHP 7.1 include nullable types; catching of multiple exception types in a single catch statement; curl HTTP/2 server push support; void return types, performing an action that does not return anything; and generalized support of negative string offsets. The 7.1 release also will feature warnings about invalid strings in arithmetic, and a class constant visibility modifiers capability introduces modifiers to mirror properties and methods.
"Ultimately I think people care a lot more about performance than some fancy new syntax," Zuraski said "PHP is a mature language, which explains the relatively slow adoption of recent versions of PHP 5.x and the apparently relatively fast adoption of PHP 7, which is predominantly about performance."
Although a tentative release schedule has PHP 7.1 possibly shipping this November following a multitude of release candidates, the actual release could slip until as far out as 2018, Suraski said.