The PHP development team is proud to announce the immediate availability of PHP 5.5.0. This release includes a large number of new features and bug fixes.
The key features of PHP 5.5.0 include:
20-Jun-2013
Drop support for bison < 2.4 when building PHP from GIT source
Improved Zend Engine:
Added ARMv7/v8 versions of various Zend arithmetic functions that are implemented using inline assembler
Added systemtap support by enabling systemtap compatible dtrace probes on linux
Optimized access to temporary and compiled VM variables. 8% less memory reads
The VM stacks for passing function arguments and syntaticaly nested calls were merged into a single stack. The stack size needed for op_array execution is calculated at compile time and preallocated at once. As result all the stack push operations don't require checks for stack overflow any more
General improvement:
Added generators and coroutines.
Added "finally" keyword.
Added simplified password hashing API.
Added support for constant array/string dereferencing.
Added Class Name Resolution As Scalar Via "class" Keyword
Added support for using empty() on the result of function calls and other expressions
Added support for non-scalar Iterator keys in foreach
Added support for list in foreach
Core:
Added Zend Opcache extension and enable building it by default.
Added array_column function which returns a column in a multidimensional array
Added boolval()
Added "Z" option to pack/unpack
Added optional second argument for assert() to specify custom message
Added support for changing the process's title in CLI/CLI-Server SAPIs. The implementation is more robust that the proctitle PECL module
Improve set_exception_handler while doing reset
Return previous handler when passing NULL to set_error_handler and set_exception_handler