[Solar-talk] proposed usage of constants in place of strings for status in Solar_Auth_Adapter

[Antti Holvikari]

On Mon, Mar 24, 2008 at 12:07 AM, Leo Chiao <leo.chiao at gmail.com> wrote:
> Thanks for your input Antti, I completely overlooked that aspect and now
> notice that he is using locale strings to populate the "status_text" flash
> based on the user status string.
>
> Do you mind elaborating on your point about clumsy if/else structures? If a
> variable is used soley to signify state or won't change, why would you avoid
> defining a const for it?

Ok, here's a few points:

* You usually use integer values for constants, right, so you'd need
an if/else to "use" that value somehow. This is one reason why Solar
doesn't use constants, **string constants** map **directly** to locale
keys (the "use"). PHP is such a high-level language that often a
constant value plays a significant role in what will be displayed on
the page. An integer is the worst value for this. One example: genres.
You are most likely to display the genre of a user on the page. Using
a constant for "man" and "women" would mean you'd need to check
whatever you have in a variable and compare it to the value of a
constant to be able to echo it.

That said, in a "low-level" PHP library constants could make sense.
Say, use a different algorithm depending on a constant. This could be
signaled from a method to another method with a constant:
readBytes(Class::BIG_ENDIAN). This makes perfect sense. Very clear and
will never "touch" the UI.

Now, if you used a string for a constant's value I think it would
kinda defeat the purpose. You'd end up using the string literal itself
for checking a value than the constant name. I know I would. Wait, I
could use the literal **without** even the check (which brings to my
first point).

* Strings are "cheap" in PHP. You will never create a bottleneck with
using strings instead of constants.

You have a point there that you'd catch some typos with constants.
IMHO that is alone just not worth using constants.

Every time I've tried using constants I've switched back to plain
strings. Happy to hear other opinions/experiences.

-- 
Antti Holvikari <http://anttih.com>