PHP Extension Development with PHP-CPP: Object Oriented Code

This article continues the exploration of building PHP extensions using PHP-CPP, focusing on object-oriented features. We'll create a Complex number class to illustrate the library's capabilities.

To begin, we'll adapt the PHP-CPP project template. Rename yourtextension.ini to complex.ini and update its content to extension=complex.so. Modify the Makefile as follows:

<code class="language-makefile">NAME                =   complex
INI_DIR             =   /etc/php5/cli/conf.d</code>

Next, we'll define the Complex class in main.cpp.

Key Concepts:

• PHP-CPP simplifies object-oriented PHP extension development using familiar C syntax.
• The Complex class showcases C and PHP-style constructors/destructors for seamless integration.
• Methods like mod() and add() demonstrate method registration, allowing PHP scripts to directly use C class functionality.
• PHP "magic methods" (e.g., __toString()) enhance interaction with objects in PHP scripts.
• The article provides a complete guide to configuring, compiling, and testing PHP extensions.

C and PHP Constructors/Destructors:

C uses constructors (functions with the class name, no return type) and destructors (class name prefixed with ~, no return type, no parameters). PHP uses __construct() and __destruct(). PHP-CPP supports both:

<code class="language-cpp">class Complex : public Php::Base {
private:
    double r = 0, i = 0;

public:
    Complex() {}
    virtual ~Complex() {}

    Php::Value getReal() { return r; }
    Php::Value getImage() { return i; }

    void __construct(Php::Parameters &params) {
        if (params.size() == 2) {
            r = params[0];
            i = params[1];
        } else {
            r = 0;
            i = 0;
        }
    }
    // ... other methods ...
};</code>

Important points:

1. All classes must inherit from Php::Base.
2. Both C and PHP-style constructors are implemented.
3. getReal() and getImage() provide access to private members.
4. The PHP constructor handles initialization.

mod() Method:

This method calculates the modulus of a complex number:

<code class="language-cpp">Php::Value mod() const {
    return (double)sqrt(r * r + i * i);
}</code>

Remember to include <cmath></cmath> for sqrt(). PHP-CPP supports specific member function signatures (see the article for details).

add() Method:

Adding two complex numbers:

<code class="language-cpp">Php::Value add(Php::Parameters &params) {
    Php::Value t = params[0];
    Complex *a = (Complex *)t.implementation();

    r += (double)a->getReal();
    i += (double)a->getImage();

    return this;
}</code>

t.implementation() is crucial for casting a Php::Value to its underlying C object.

__toString() Method:

For user-friendly output:

<code class="language-cpp">Php::Value __toString() {
    std::ostringstream os;
    os << r;
    if (i >= 0) os << "+";
    os << i << "i";
    return os.str();
}</code>

Include <sstream></sstream> for string manipulation.

Function Registration:

Registering the class and its methods:

<code class="language-cpp">extern "C" {
    PHPCPP_EXPORT void *get_module() {
        static Php::Extension myExtension("complex", "1.0");
        Php::Class<complex> complex("Complex");
        complex.method("mod", &Complex::mod, {});
        complex.method("__construct", &Complex::__construct);
        complex.method("add", &Complex::add, {Php::ByVal("op", "Complex", false, true)});
        myExtension.add(std::move(complex));
        return myExtension;
    }
}</complex></code>

Compilation, Installation, and Testing:

Compile and install using make && sudo make install. Test with PHP code (see the original article for examples).

Namespace Encapsulation:

Wrapping the class in a namespace (trComplex in this example) requires minimal changes (see the original article for details). The key is adjusting the namespace in the get_module() function and using the fully qualified name in PHP code.

Conclusion:

PHP-CPP offers a streamlined approach to creating PHP extensions. While documentation improvements are suggested, its ease of use and features make it a valuable tool. The article provides a comprehensive guide, covering essential aspects of object-oriented PHP extension development.

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