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Date: Tue, 5 Jan 2021 13:39:36 +0000
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Subject: Re: [PHP-DEV] [RFC] Configurable callback to dump results of
 expressions in `php -a`
From: rowan.collins@gmail.com (Rowan Tommins)

On 03/01/2021 20:45, tyson andre wrote:
> __debugInfo() is a slight improvement, but the human-readable representation of an object isn't always the same thing as the debug representation of the object.
> A human-readable representation might be `Point(x: 1, y: 2)`, where var_dump or var_export(`__set_state`)
> is much longer, and I don't believe var_dump is a one size fits all solution for both simple and recursive data structures,
> especially since `__debugInfo` predates the repl.


A couple of notes on this:

- The readline-based shell for "php -a" was added in PHP 5.1 
[https://www.php.net/manual/en/features.commandline.interactive.php] and 
__debugInfo not until 5.6 [https://wiki.php.net/rfc/debug-info]

- I agree that the existing debug outputs are quite verbose, but I don't 
think that's a problem unique to the REPL. var_export() is constrained 
to render valid PHP code, but print_r() and var_dump() could and perhaps 
should represent objects more compactly.

- That compact representation of a Point would be useful pretty much 
everywhere anyone wanted debug output. It would also be possible to 
build it on top of the existing functionality (key-value pairs from 
__debugInfo if defined, else all properties).

- Allowing objects to overload the output seems much preferable to the 
formatting function having to know all the special cases, so I'm not 
convinced of the need to hook the entire output for the shell.

- I can't find any references off-hand, but I'm pretty sure popular 
REPLs in other languages take that approach: use existing 
pretty-printing mechanisms from the language, which in turn can be 
overloaded by individual types / classes.


Regards,

-- 
Rowan Tommins
[IMSoP]