Edit report at https://bugs.php.net/bug.php?id=63156&edit=1
ID: 63156
Updated by: ni...@php.net
Reported by: herb at bobbingwide dot com
Summary: using if ( expression ) requires functions to be
declared before calls
Status: Duplicate
Type: Bug
Package: *Programming Data Structures
Operating System: Windows XP
PHP Version: 5.3.17
Block user comment: N
Private report: N
New Comment:
@herb: You are using a conditional function definitions, in which case PHP
*can't* know which function will be used, at least not in the general case.
Function hoisting only works with "top-level" function declarations.
This is also documented on http://php.net/manual/en/functions.user-defined.php.
See in particular those two lines:
> Functions need not be defined before they are referenced, *except* when a
> function is conditionally defined as shown in the two examples below.
> When a function is defined in a conditional manner such as the two examples
> shown. Its definition must be processed *prior* to being called.
A very simple solution to your particular problem (which at the same time will
yield cleaner code) is to abort early if the constant is defined:
<?php
if (defined('CONSTANT')) {
return;
}
// the rest of the file here
Previous Comments:
------------------------------------------------------------------------
[2012-09-25 14:11:14] herb at bobbingwide dot com
laruence... agreed. That's how I solved it, as documented in my original report.
I was just commenting on the original response in #17055.
It was the unexpected behaviour that threw me more than anything.
------------------------------------------------------------------------
[2012-09-25 12:22:07] larue...@php.net
hmm, it's not the only way, since you can get it works well by declare it
before reference to it:
<?php
if ( true ) {
function a() {
echo "a" . PHP_EOL;
}
a();
}
------------------------------------------------------------------------
[2012-09-25 11:33:02] herb at bobbingwide dot com
I accept that this is a duplicate of #17055.
And since derick said, in response to #17055, "I don't see any fast
implementation of this.", 10 years ago (May 2002), I'm inclined to agree that
this will have to be dealt with as a documentation problem.
However, in my particular scenario the original response to the problem... "The
only way to prevent this is to move out the function declaration out of the
branch and in the main scope of the script." is not acceptable since the whole
point of the encapsulating code was to prevent the functions from being
multiply
defined.
So I believe the documentation should provide a clear explanation of the
parsing
and interpretation processes involved.
------------------------------------------------------------------------
[2012-09-25 09:46:26] larue...@php.net
dup to #17055
------------------------------------------------------------------------
[2012-09-25 05:13:48] re...@php.net
Top level declaration are available after compiling, but conditional declaration
can only be available after executed. (since PHP itself didn't do optimization,
i`f(true) {doSomething();}` is not equal to `doSomething();` exactly )
the same rules for class declarations.
This could be classified as a documentation problem.
------------------------------------------------------------------------
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