To get all user-defined functions in PHP, you can use get_defined_functions()['user']; the specific steps are: 1. Call get_defined_functions() to get an array containing all functions; 2. Access the 'user' key from the return result to get a list of user-defined functions; 3. Make sure that the method is called after the function definition to obtain accurate results; this method is suitable for debugging, plug-in system, and document generation. Note that function names are case-sensitive, namespace functions will have backslashes, anonymous functions will not be listed, and have little performance impact.
In PHP, if you want to know all user-defined functions in the current environment, you can use the built-in function get_defined_functions() and combined with filtering. It itself returns a complete list of built-in functions and user-defined functions, but you can get only the parts you care about with parameters or subsequent processing.
Methods to get all user-defined functions
PHP provides the get_defined_functions() function, which returns an array containing all defined functions. By default, it returns two keys: internal (built-in function) and user (user defined function).
$functions = get_defined_functions(); $userFunctions = $functions['user'];
The above code can get an array of function names written by all users themselves.
It should be noted that only functions that have been defined before calling get_defined_functions() will be listed. So you'd better call it later in the script running, or make sure that the function you want to check has been loaded.
Examples of usage scenarios: debugging, plug-in system, document generation, etc.
- Debug Tools : Some debug panels list all available functions to help developers understand the functions in the current environment.
- Plugin mechanism : If you are writing a plugin system that allows users to register callbacks, checking whether the user function exists is a common operation.
- Document Generator : Automatically extract user functions and generate document descriptions, such as tools like PHPDoc.
For example:
function my_custom_function() {
echo "Hello";
}
$funcs = get_defined_functions();
if (in_array('my_custom_function', $funcs['user'])) {
echo 'function exists';
}This is useful when building scalable systems.
Notes and FAQs
- Case insensitive : PHP function names are case insensitive, so it is also recommended to use case insensitive when comparing.
- Namespace function : If you use a namespace, the function name will be backslashed, such as
'MyNamespace\myFunc'. - Anonymous functions/closures do not appear here :
get_defined_functions()records only functions that are explicitly defined usingfunction name(), and does not include closures or dynamically created functions. - The performance impact is very small : it will not usually become a bottleneck, but if used in high-frequency loops, you should still pay attention.
Basically that's it. Mastering the usage of get_defined_functions()['user'] is very convenient when you need to see which functions are available in the current context.
The above is the detailed content of How to get all user-defined functions in PHP?. For more information, please follow other related articles on the PHP Chinese website!
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