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Date: Tue, 7 Nov 2006 09:26:42 +0000
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Subject: Re: [PHP-DEV] [PATCH] Scalar type hinting ;)
From: rquadling@googlemail.com ("Richard Quadling")

Not in direct reply to any message.

Type hinting is on for classes and arrays (maybe resources too - not
sure - but certainly a good idea if not). Why? From my perspective, it
allows me to not deal with potential errors either in the data or my
coding or another developers coding.

Type hinting is part of the documentation. Sure, hungarian notation of
variable names (where the type is represented within the variable name
itself) is a good start, but when you get to things like a 4d array of
string and integer pairs, you get more notation than variable name.

Extending type hinting to scalars is the next step. The loose typing
of PHP is great, but as mentioned by Richard Lynch, we have to more or
less move away from it for user input and DB input.

Even when we store data in the session it is stored in type, so,
pretty much after getting the source data to operate on, the type is
fixed.

You don't store a number in the session and get it back as a string to
convert back to a number in the next session usage. You store a
number, you get a number back.

So, where is the use for loose type? You can't loose type objects or
arrays or resource. You no longer need to loose type user input or DB
input (cause you are now using SOME sort of input filtering
mechanism).


An issue is very much where you have mixed types (which many of the
PHP functions support). How do you hint this? You could either used
mixed or blank, but maybe you can supply multiple types which the
function will support.

Maybe for V6 type hinting for scalars could be available, but output
purely E_NOTICE. Really make them just a hint. A suggestion. This will
allow auto documentors get to grips with things, allow code complete
editors deal with user defined functions, etc.

Sometime after that the facility to make the hints become enforcers.
There would be a published list of conversion mechanisms (the
equivalent PHP function in effect). You could potentially allow user
defined conversions for user defined types though I would see this as
a WIBNI, rather than a MH.

If you don't have any hints then nothing changes. If you do have
hints, then you would have to accept the hit in the additional
checking. If you have the enforcement, then you would have to deal
with the NULLs that would result in failed conversions (I would
recommend NULL rather than any other value for failed conversions).




-- 
-----
Richard Quadling
Zend Certified Engineer : http://zend.com/zce.php?c=ZEND002498&r=213474731
"Standing on the shoulders of some very clever giants!"