One Method with Multiple Parameters or Multiple Methods with One Parameter? - php

Question

Imagine a "Games" class used to track games between opponents. Is it better OOP to have 1 method to retrieve games based on user input parameters or is it better to have multiple methods specific to the retrieval goals?
class Games {
function get_games($game_id = NULL, $stadium_id = NULL, $start_date = NULL,
$end_date = NULL, $count = 999); {}
}
VS
class Games {
function get_all_games($count = 999); {}
function get_game_by_id($game_id = 1); {}
function get_games_by_stadium($stadium_id = 1); {}
function get_games_by_dates($start_date = NULL; $end_date = NULL) {}
}
Explanation of benefits and any coding / snytax tips would be appreciated. Thanks.

Answer 1

The more I practice OOP the more I find myself following a rule about passing parameters to methods. Kind of like having many levels of nested if statements, I find that if I have more than two I might be doing something wrong.
Keep your code simple. You're writing a method that does something, not a block of procedural code that does everything. If you want to get a game, then get a game. If you want to get a list for a date range, then do that.
However I would point out that you don't really need get_all_games() - You can just allow for get_games_by_dates() to be passed with no parameters. If it doesn't get any then it would get the games for every date since forever (all the games)

Answer 2

I would always err on the side of OOP code. the reason being is that it makes you code much easier to maintain and read. The more functions you have the easier it is to follow code later on down the road

Answer 3

I would go for separate methods since you are using lots of paramaters with default values.
If you want to get all games you would have to do:
$games->get_games(NULL, NULL, NULL, NULL, 999);

Answer 4

Assuming that your get_....() functions are returning all game data, I would write a single function to return this data, based on an id passed in, and write a series of find_...() functions to return an array of found ids. This will have the added benefit of making it easier to override the data retrieval code in decendant classes.
class Games {
public function get_game($game_id) {
// Return game details (array/object) for $game_id, or FALSE if not found.
}
public function find_all_games() {
// Return array of ids for all games.
}
public function find_games_by_dates($start_date = NULL, $end_date = NULL) {
// Return array of ids between $start_date and $end_date unless NULL.
}
}
You can then call:
$oGames = new Games() ;
$aGames = $oGames->find_all_games() ;
foreach($aGames as $id) {
$aGame = $oGames->get_game($id) ;
if($aGame !== FALSE) { // This check might be skipped if you trust the array of ids from find_all_games().
// Assuming an array is returned.
echo "Game Found: ".$aGame['name']."\n" ;
}
}

Answer 5

The benefit of "multiple methods specific to the retrieval goals" is that you can add/remove goals. The problem with using one monolithic function with a bunch of parameters is that, should you decide to add/remove a way to get games, you'd have to change the interface. Which would break any code that uses it.
Each method should be as concise as possible, performing only one function.