Class Properties

This chapter covers how to define a class property.

Code sample for this chapter, with additional examples, is available here.

Userland PHP Code Snippet

The code below shows how a class property would be declared in userland PHP code.

class Hdi {
  public int $value;
}

Internal PHP Code

The following sections show all required code to declare and implement a class property internally in PHP.

PHP Stub (hdi.stub.php)

The stub file may or may not declare class properties, but the stub generator script (gen_stub.php) will not produce any output related to them as they are implementation specific.

Argument Information (hdi_arginfo.h)

Class properties are not referred to nor registered in the argument information file, so it can be skipped.

Implementation (hdi.c)

zend_string *propName = zend_string_init("value", sizeof("value") - 1, false);
zval propDefaultValue;
/* default property value (undefined) */
ZVAL_UNDEF(&propDefaultValue);

zend_declare_typed_property(
  classEntry,
  propName,
  &defaultValue,
  ZEND_ACC_PRIVATE,
  NULL,
  (zend_type)ZEND_TYPE_INIT_MASK(MAY_BE_LONG)
);
zend_string_release(propName);

Macros and Functions:

Visibility options:

Type options:

Manipulating Property Values

Update/Set a Property

Updating a property value is straight forward:

  • update function (zend_update_property_long)
    • class entry (classEntry)
    • object reference (Z_OBJ_P(ZEND_THIS) ie. $this)
    • property name string ("value")
    • property name size (sizeof)
    • value (42)
zend_update_property_long(
  classEntry,
  Z_OBJ_P(ZEND_THIS),
  "value",
  sizeof("value") - 1,
  42
);

Note that for static properties, zend_update_property_long must be replaced by its static version (zend_update_static_property_long), that does not have an object argument.

Macros and Functions:

Read a Property

Reading a property value requires a bit more leg work:

  • read function (zend_read_property)
    • class entry (classEntry)
    • object reference (Z_OBJ_P(ZEND_THIS) ie. $this)
    • property name string ("value")
    • property name size (sizeof)
    • ???
    • ???
zval rv;
zval *value = zend_read_property(
  classEntry,
  Z_OBJ_P(ZEND_THIS),
  "value",
  sizeof("value") - 1,
  true,
  &rv
);

Note that for static properties, zend_read_property must be replaced by its static version (zend_read_static_property), that does not have an object argument.

Macros and Functions:

Copyright (c) 2022 - Flavio Heleno