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Date: Fri, 27 Feb 2015 17:51:12 +0000
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Subject: Re: [PHP-DEV] Coercive STH - some real world tests and updated RFC
From: lester@lsces.co.uk (Lester Caine)

On 27/02/15 16:46, Damien Tournoud wrote:
> You probably haven't read the examples that I pasted. If you think that it
> makes sense to return an error code if the function is called with invalid
> arguments, it should be done consistently. The current behavior is just an
> absurdly inconsistent, it is really hard to find an argument in favor of
> it, other than the argument in favor of backward compatibility.

That some changes to the logic of substr have been made is a fact.
Negative values were added to read back from the end of the string a
function that has been played with over time,

# It is NOT OK to start reading past the end of the string, no, no. Bad
programmer.
If there are no characters left ... the string is empty.

# But it is OK to ask for a bigger slice than the length of the string.
Yes ... length is the MOST it will return, if less are available then
that is all you can get.

# It is also OK to read past the begining of the string, why not.
If the reading point does not cut characters then yes this is
consistent. If the length requested was '2', then I would expect 'a' and
false which I think was what the 'bug fix' for PHP5.2.2 was supposed to
do, but it was reverted later in 5.2.7

# On the other hand, it is NOT OK to stop reading before the end of the
string. Bad programmer.
Take 2 characters off the string ... empty string.

This may not be what YOU want substr to do and it would perhaps be
useful to ADD additional checks so that 'false' is returned when it
can't created a string because of the 'invalid arguments', but type
hints makes no difference to part of the jigsaw. What happens is exactly
what one would expect ... nothing left in the string -> an empty string.
Having then to check every time for a '0' string length got shortened to
simply being able to check 'is there a string' yes/no, and if no you can
do something else. There is nothing inconsistent ...

-- 
Lester Caine - G8HFL
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