1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
|
<h1>Limiting function parameters</h1>
<p>
PHP has a mechanism to enforce function parameters types, and to accept
parameters either by reference or by value. In the examples above, we have
not yet used that mechanism yes: it is up to the function implementations
themselves to inspect the 'Parameters' object, and check if the
variables are of the right type.
</p>
<p>
However, the 'Extension::add()' method takes a third optional parameter that
you can use to specify the number of parameters that are supported, whether
the parameters are passed by reference or by value, and what the type of
the parameters is:
</p>
<p>
<pre class="language-c++"><code>
#include <phpcpp.h>
extern void example(Php::Parameters &params);
extern "C" {
PHPCPP_EXPORT void *get_module() {
static Php::Extension myExtension("my_extension", "1.0");
myExtension.add("example", example, {
Php::ByVal("a", Php::Type::Numeric),
Php::ByVal("b", "ExampleClass"),
Php::ByRef("c", "OtherClass")
});
return myExtension.module();
}
}
</pre></code>
</p>
<p>
Above you see that we passed in additional information when we registered the
"example" function. We tell our extension that our function accepts three parameters:
the first parameter must be a regular number, while the other ones are object
instances of type "ExampleClass" and "OtherClass". In the end, your native C++
"example" function will still be called with a Php::Parameters instance, but
the moment it gets called, you can be sure that the Php::Parameters object
will be filled with three members, and that two of them are objects of the
appropriate type, and that the third one is also passed by reference.
</p>
<h2>Working with variables</h2>
<p>
Variables in PHP are non-typed. A variable can thus hold any possible type:
an integer, string, a floating point number, and even an object or an array.
C++ on the other hand is a typed language. In C++ an integer variable always
has a numeric value, and a string variable always hold a string value.
</p>
<p>
When you mix native code and PHP code, you will need to convert the non-typed
PHP variables into native variables, and the other way round: convert native
variables back into non-typed PHP variables. The PHP-CPP library offers the
"Value" class that makes this a very simple task.
</p>
<p>
|
