| Re: Using function prototypes in code [message #175040 is a reply to message #175036] |
Fri, 05 August 2011 06:35   |
alvaro.NOSPAMTHANX
Messages: 277
Registered: September 2010
Karma:
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Senior Member |
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El 05/08/2011 2:53, webber escribió/wrote:
> In the interest of clarity and maintainability I would like to be able
> to write code that makes it clear what kind of arguments a function
> expects and what it returns.
>
> This is what I tried:
>
> function integer int_func(string $s) {
> // does something like, say, converting "five" to 5
> }
>
> There are two problems:
> 1 The appearance of a type name before the function name is treated as
> a syntax error
> 2 Even if I forget about declaring the return type and code it instead
> as
>
> function int_func(string $s) {
> ...
> }
>
> I get a run-time error when I call the function with a string. (eg
> $var = int_func("five");) The error message says"Catchable fatal
> error: Argument 1 passed to int_func() must be an instance of string,
> string given".
>
> It seems that basic data types cannot be specified in ths way although
> (intstances of) classes can. I have successfully used the technique to
> catch run-time errors of wrong object types when testing, but am
> surprised that I can't use it to trap unexpected basic types - or at
> least to document what is expected.
PHP data types are explained at "Language Reference-> Types":
http://www.php.net/manual/en/language.types.php
And type hinting is at "Language Reference-> Classes and Objects-> type
Hinting":
http://www.php.net/manual/en/language.oop5.typehinting.php
«Type Hints can only be of the object and array (since PHP 5.1) type.
Traditional type hinting with int and string isn't supported.»
function int_func(string $s) {} does not trigger a syntax error because
it's perfectly possible to do this:
class string{
}
> To confuse me a bit further, I can't find a definitive list of the
> basic type names. For example, is it "integer" or "int"?
In PHP you cannot define variables as integer, float or string, so there
aren't keywords as such. The closest you'll find is:
http://www.php.net/manual/en/language.types.type-juggling.php#language.type s.typecasting
--
-- http://alvaro.es - Álvaro G. Vicario - Burgos, Spain
-- Mi sitio sobre programación web: http://borrame.com
-- Mi web de humor satinado: http://www.demogracia.com
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