PHP/resource

About

In PHP, a "resource" value is an opaque internal pointer for handling certain types of I/O-ish operations.

Syntax

As of PHP 8.5, although "resource" is "soft-reserved and is used as a documentation pseudotype, there is no actual "resource" type; the only type which is currently known to be compatible with resource variables is "mixed". PHP currently interprets invocation of "resource" as a type as a reference to an unknown class named "Template:Fmt/arg\resource".

Types

There are many specialty resource-types defined by extensions, and a handful of more general types:

type	subtype	functions
/curl/	cURL handle
/process/		proc_open(), proc_get_status(), proc_terminate(), proc_close()
/stream/	dir handle
/stream/	file handle
/stream/	process handle
/socket/	file handle
/ssh2/ session
/ssh2/ listener
/ssh2/ SFTP
/ssh2/ publickey system

Source: List of Resource Types

Advanced

New stream resource types can be defined in code with stream_wrapper_register().

Functions

These are just the general functions that apply to all resources; there are many others that do things with specific types of resources. In general, this is all not very well documented (there is plenty of documentation, but very little of it explains how things work).

• get_resource_id()
• get_resource_type()
• is_resource()
• If passed a resource variable, get_debug_type() will indicate whether it is open or closed. (Surely there is some more rigorous way to get this information, however.)

Links

Reference

• Resources
  • List of Resource Types