If you use the variable $objectVar to change the state of the Object instance, those changes also show up under $assignment, because it is pointing at that same Object instance.īut it is not exactly the same as a reference. This makes it behave in some ways like a reference. $assignment has a different data slot from $objectVar, but its data slot holds a handle to the same object. ![]() But they are not references, so if one of the variables is assigned a new value, it does not affect the other variable. This means that both variables can change the state of the same object instance. What makes this tricky is that when you take a variable which holds an object handle, and you assign it to another variable, that other variable gets a copy of the same object handle. So, the object handle, although not directly visible to the programmer, is one of the basic datatypes. This is an identifier that points at one particular instance of an obect. ![]() Instead, an object's "handle" goes in the data slot. They cannot be held in the data slots directly. Now, the trick is that object instances are not like the basic data types. When you assign one variable to another, you are copying the contents of one data slot to another data slot. When you create a reference, you are making a second name that points at the same data slot. ![]() ![]() Each one is a name that points to a data slot that can hold a value that is one of the basic data types: a number, a string, a boolean, etc. But I think I've figured out what's going on.įirst, think of variables in PHP as data slots. I was confused at first about object assignment, because it's not quite the same as normal assignment or assignment by reference. Getting Started Introduction A simple tutorial Language Reference Basic syntax Types Variables Constants Expressions Operators Control Structures Functions Classes and Objects Namespaces Enumerations Errors Exceptions Fibers Generators Attributes References Explained Predefined Variables Predefined Exceptions Predefined Interfaces and Classes Predefined Attributes Context options and parameters Supported Protocols and Wrappers Security Introduction General considerations Installed as CGI binary Installed as an Apache module Session Security Filesystem Security Database Security Error Reporting User Submitted Data Hiding PHP Keeping Current Features HTTP authentication with PHP Cookies Sessions Dealing with XForms Handling file uploads Using remote files Connection handling Persistent Database Connections Command line usage Garbage Collection DTrace Dynamic Tracing Function Reference Affecting PHP's Behaviour Audio Formats Manipulation Authentication Services Command Line Specific Extensions Compression and Archive Extensions Cryptography Extensions Database Extensions Date and Time Related Extensions File System Related Extensions Human Language and Character Encoding Support Image Processing and Generation Mail Related Extensions Mathematical Extensions Non-Text MIME Output Process Control Extensions Other Basic Extensions Other Services Search Engine Extensions Server Specific Extensions Session Extensions Text Processing Variable and Type Related Extensions Web Services Windows Only Extensions XML Manipulation GUI Extensions Keyboard Shortcuts ? This help j Next menu item k Previous menu item g p Previous man page g n Next man page G Scroll to bottom g g Scroll to top g h Goto homepage g s Goto search
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