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Subject: Re: [PHP-DEV] invalid params return value
From: stas@zend.com (Stanislav Malyshev)

Hi!

> Would changing the returning value to Null to indicate invalid
> arguments (or any other error condition) would create a significant BC
> surely? Just how many functions are documented with the entity
> &return.falseforfailure;? (198 files using this so far vs Return
> &null; which is used very rarely).

There are different kinds of failure. There's failure for the function 
(i.e. function tried to do something and failed, like couldn't open the 
file) and failure where function wheren't even executed (like you called 
fopen without giving it a filename). Some functions return the same in 
both cases, some do not. I'm sure half of the functions documented as 
&return.falseforfailure; return NULL on incorrect args.

As for BC - it may break some scripts that don't check properly but 
having each function do different thing is worse, since you couldn't 
even write a proper check - since you have no way of knowing what to 
check for.

> Differentiating between False/Null (something was wrong) and
> False/Null (the answer to the question you asked is False or Null) is
> pretty impossible without constantly checking the manual to see what
> the return values for failure is.

It's impossible with or without the change, it's entirely different 
question.

> Of course, the question I would next ask (and, oh look, am doing so)
> is could an exception be thrown? Invalid arguments is a pretty

No, exception is not a good thing (that's why I didn't mention it) since 
a lot of code isn't organized in a way that exceptions can be properly 
handled, and using exceptions in this case would pretty much lead to 
using exceptions for any error handling which I don't think PHP 
community agrees to, and also entirely different topic.
-- 
Stanislav Malyshev, Zend Software Architect
stas@zend.com   http://www.zend.com/
(408)253-8829   MSN: stas@zend.com