# RFC http://wiki.php.net/rfc/horizontalreuse#traits_-_reuse_of_behavior
# Ok, here we go, I guess that will result in more discussion, which is fine
# by me. But now, the patch is here, and properly archived.
#
# See below a list of notes to the patch, it also includes a list of
# points which should be fixed
#
# Internals of the Traits Patch
# -----------------------------
#
# Open TODOs
# """"""""""
#
# - Reflection API
# - support for traits for internal classes
# - currently destroy_zend_class does not handle that case
#
# Introduced Structures
# """""""""""""""""""""
#
# Data structures to encode the composition information specified in the
# source:
# - zend_trait_method_reference
# - zend_trait_precedence
# - zend_trait_alias
#
# Changes
# """""""
#
# zend_class_entry
# - uses NULL terminated lists of pointers for
# - trait_aliases
# - trait_precedences
# - do you prefer an explicit counter?
# - the information is only necessary during class composition
# but might be interesting for reflection
# - did not want to blow up class further with not really necessary length counters
#
# added keywords
# - trait
# - insteadof
#
# Added opcodes
# ZEND_ADD_TRAIT
# - similar to ZEND_ADD_INTERFACE
# - adds the trait to the list of traits of a class, no actual composition done
# ZEND_BIND_TRAITS
# - emitted in zend_do_end_class_declaration
# - concludes the class definition and will initiate the trait composition
# when the class definition is encountered during runtime
#
# Added Flags
# ZEND_ACC_TRAIT = 0x120
# ZEND_ACC_IMPLEMENT_TRAITS = 0x400000
# ZEND_FETCH_CLASS_TRAIT = 14
#
# zend_vm_execute.h
# - not sure whether the handler initialization (ZEND_ADD_TRAIT_SPEC_HANDLER,
# ZEND_BIND_TRAITS_SPEC_HANDLER) is correct, maybe it should be more selective
#
# zend_compile.c
# - refactored do_inherit_method_check
# split into do_inherit_method_check and do_inheritance_check_on_method
# - added helper functions use a '_' as prefix and are not mentioned in the
# headers
# - _copy_functions
# prepare hash-maps of functions which should be merged into a class
# here the aliases are handled
# - _merge_functions
# builds a hash-table of the methods which need to be added to a class
# does the conflict detection
# - reused php_runkit_function_copy_ctor
# - it is not identical with the original code anymore, needed to update it
# think I fixed some bugs, not sure whether all have been reported back to runkit
# - has to be renamed, left the name for the moment, to make its origin obvious
# - here might be optimization potential
# - not sure whether everything needs to be copied
# - copying the literals might be broken
# - added it since the literals array is freed by efree and gave problems
# with doubled frees
# - all immutable parts of the zend_op array should not be copied
# - am not sure which parts are immutable
# - and not sure how to avoid doubled frees on the same arrays on shutdown
# - _merge_functions_to_class
# does the final merging with the target class to handle inherited
# and overridden methods
# - small helper for NULL terminated lists
# zend_init_list, zend_add_to_list
#
# zend_language_parser.y
# - reused class definition for traits
# - there should be something with regard to properties
# - if they get explicitly defined, it might be worthwhile to
# check that there are no collisions with other traits in a composition
# (however, I would not introduce elaborate language features to control that
# but a notice for such conflicts might be nice to the developers)
The following pseudo-code explains how it should be used in opcode cache.
function cache_compile_file($filename) {
if (!is_cached($filename)) {
...
orig_compiler_options = CG(compiler_optins);
CG(compiler_options) |= ZEND_COMPILE_IGNORE_INTERNAL_CLASSES |
ZEND_COMPILE_DELAYED_BINDING;
$op_array = orig_compile_file($filename);
CG(compiler_options) = orig_copiler_options;
...
} else {
$op_array = restore_from_cache($filename);
}
zend_do_delayed_early_binding($op_array);
}
