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Subject: Re: [PHP-DEV] [RFC] Working With Substrings
From: rowan.collins@gmail.com (Rowan Tommins)

On 14/02/2023 15:32, Thomas Hruska wrote:
> Hello Internals,
>
> I would like to start the discussion on adding several functions and 
> parameters to existing functions for improved substring handling in PHP:
>
> https://wiki.php.net/rfc/working_with_substrings


Hi Thomas,

Thanks for your effort on this, I think efficient string handling 
functions would be a major help for the ecosystem, allowing library 
authors to do things in plain PHP code which currently defer to C 
extensions just for performance.


My first thought opening the RFC was to see a function signature with 9 
arguments and immediately wonder how to refactor it into something more 
manageable. Just writing *tests* for all the combinations sounds like a 
nightmare, let alone understanding code that uses them all.

As I read through, I had a similar feeling about the need to 
copy-and-paste the same two parameters onto so many functions.


Luckily, I think the RFC contains the seed of the solution to both 
problems: what you refer to as "virtual buffers". These seem to be 
crying out to be a new data type, with their own API - probably using OO 
style, given general fashions.

Framed around that, I think we can split out a few different concerns:

* Methods to take a string, and make a new, writeable buffer pointing at 
all or part of it
* Methods to access parts of a buffer, as a string or another buffer
* Methods to efficiently write to, delete from, or overwrite, parts of a 
buffer
* Methods to explicitly manage the memory used by the buffer
* Finally, support for writing to, or reading from, a buffer instead of 
a string in a number of existing functions


Thinking about exactly what those methods should look like leads me to 
my next thought: we should be learning from prior art here. Are there 
other languages which already do this well, which PHP could emulate? Are 
there other languages which already do this *badly*, whose mistakes PHP 
could explicitly learn from?

What comes to my mind immediately is that both Java and C# have 
"StringBuilder" classes, which cover at least some of these use cases. 
C#, in particular, had a lot of very smart people paid to design it, 
able to learn from mistakes Java had already made.


Regards,

-- 
Rowan Tommins
[IMSoP]