At 07:56 PM 2/8/2006, Matt Arnilo S. Baluyos (Mailing Lists) wrote:
I have a config.inc.php file which basically contains all the
configuration info that the applications needs (directory/file
locations, database credentials, etc). The information there is set
using the define() function.
However, I've seen some open-source projects which either use
$variables or associative arrays to save the values.
A small but significant factor in deciding whether to use define()d
constants is that constants can't be integrated into expressions as
neatly as can variables.
Variables can be embedded in expressions:
$sUserName = "Froggy";
echo "Variable: $sUsername.";
Result: Variable: Froggy.
Constants can't be embedded in expressions:
define("sUserName", "Froggy");
echo "Constant: sUsername.";
Result: Constant: sUsername.
In order to use constants in string expressions it's necessary to use
concatenation operators:
echo "Constant: " . sUsername . ".";
Ditto for heredocs:
Variables can be embedded in heredoc expressions:
$sUserName = "Froggy";
echo <<< hdExample1
Variable: $sUserName
hdExample1;
Result: Variable: Froggy.
Constants can't be embedded in heredoc expressions:
define("sUserName", "Froggy");
echo <<< hdExample2
Constant: sUserName
hdExample2;
Result: Constant: sUsername.
Likewise, functions & classes can't be embedded in expressions
without use of concatenation operators, and can't be used in heredocs.
Of course I'm not suggesting that our inability to embed
non-variables in string & heredoc expressions removes them from the
toolbox, it simply informs our choices within a given
application. Personally I love using heredocs, functions, and
classes and simply work around the embedding limitation.
Paul
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