Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:119330
Message-ID: <152c67fc-e509-31ad-e8b0-d42572a09e0e@demon-angel.eu>
Date: Wed, 18 Jan 2023 20:43:39 +0100
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101
 Thunderbird/102.6.1
Content-Language: nl
To: internals@lists.php.net
References: <CAFPFaMLtOAkRzTsqfdhvkZZ17JpUBg_WSQBpgVU6+xg-mLt2zA@mail.gmail.com>
 <alpine.DEB.2.23.453.2301181523100.23089@singlemalt.home.derickrethans.nl>
 <04288995-54CE-41A4-BFFD-A7CF72F16D3F@gmail.com>
 <CAGBsUreK46-tg6XZmykPJx2ap-fnKbLs0=NsjwTntxbbFK2E-Q@mail.gmail.com>
In-Reply-To: <CAGBsUreK46-tg6XZmykPJx2ap-fnKbLs0=NsjwTntxbbFK2E-Q@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [PHP-DEV] [RFC] Path to Saner Increment/Decrement operators
From: mark@demon-angel.eu (Mark Baker)

On 18/01/2023 18:27, Kamil Tekiela wrote:
> When I read the RFC I was a little sceptical about the deprecation of
> string increment functionality. It's something I used in the past and I see
> no easy upgrade path. However, after reading this thread and thinking it
> over, I realize that deprecation is the right way to go. Someone said that
> it's useful when working with Excel. Excel uses bijective base-26 system.
> PHP does not. I cannot even explain what logic governs PHP string increment
> functionality.

The logic is actually fairly straightforward if you consider breaking 
the original string into blocks of alpha, numeric and non-alphameric 
characters; so a string like 'C-37AZ99' would be broken into five blocks 
of characters ('C', '-', '37', 'AZ' and '99').

Start with the rightmost block, but only if its alpha or numeric: the 
process will never increment any block of characters that is non-alphameric.

Increment the current block.

If that increment would result in an overflow (extending the size of 
that block) and there is another block to the "left" in the chain of 
blocks, then that block is reset to its "base" value (discard the 
overflow character), and the same process is repeated for incrementing 
the next block in the chain.

The process terminates when there are no more blocks in the chain, or 
when the process encounters a non-alphameric block.

The string is then "glued" back together again for the return.


In this regard, when a block is alpha characters, then the increment 
behaviour matches "Excel's bijective base-26".



-- 
Mark Baker