SymfonyCasts stands united with the people of Ukraine
If you liked what you've learned so far, dive in!
Subscribe to get access to this tutorial plus
video, code and script downloads.
Since the goal of our app is to let two ships fight each other, things
are getting interesting. For example, we could fight $myShip against $otherShip
and see who comes out as the winner.
But first, let's imagine we want to know whose strength is higher. Of course,
we could just write an if statement down here and manually check $myShip's
strength against $otherShip.
But we could also add a new method inside of the Ship class itself. Let's
create a new method that'll tell us if one Ship's strength is greater than
another's. We'll call it: doesGivenShipHaveMoreStrength(). And of course,
it needs a Ship object as an argument:
| ... lines 1 - 2 | |
| class Ship | |
| { | |
| ... lines 5 - 43 | |
| public function doesGivenShipHaveMoreStrength($givenShip) | |
| { | |
| ... line 46 | |
| } | |
| } | |
| ... lines 50 - 86 |
So just like with our printShipSummary() function, when we call this function,
we'll pass it a Ship object. What I want to do is compare the Ship object
being passed to whatever Ship object we're calling this method on. Before
I fill in the guts, I'll show you how we'll use it: if $myShip->doesGivenShipHaveMoreStrength()
and pass it $otherShip. This will tell us if $otherShip has more strength
than $myShip or not. If it does, we'll echo $otherShip->name has more
strength. Else, we'll print the same thing, but say $myShip has more strength.
| ... lines 1 - 78 | |
| echo '<hr/>'; | |
| if ($myShip->doesGivenShipHaveMoreStrength($otherShip)) { | |
| echo $otherShip->name.' has more strength'; | |
| } else { | |
| echo $myShip->name.' has more strength'; | |
| } |
Inside of the doesGivenShipHaveMoreStrength(), the magic $this will refer
to the $myShip object, the one whose name is Jedi Starship. So all we
need to do is return $givenShip->strength greater than my strength:
| ... lines 1 - 2 | |
| class Ship | |
| { | |
| ... lines 5 - 43 | |
| public function doesGivenShipHaveMoreStrength($givenShip) | |
| { | |
| return $givenShip->strength > $this->strength; | |
| } | |
| } | |
| ... lines 50 - 86 |
Ok, let's try it! When we refresh, we see that the Imperial Shuttle has more
strength. And that makes sense: the Imperial Shuttle has 50 compared with
0 for $myShip, because it's using the default value.
Let me add another separator and let's double-check to see if this is working
by setting the strength of $myShip to 100.
Ok, refresh now! Now the Jedi Starship is stronger. Undo that last change.
So how cool is this? Not only can we have multiple objects, but they can interact with each other through methods like this one. I'll show you more of this later.
Hey Brittany J.
It's pretty simple. $this is some sort of magic variable, for example, if you call $myShip->doesGivenShipHaveMoreStrength() than inside doesGivenShipHaveMoreStrength(), $this will be $myShip object, but if you call $otherShip->doesGivenShipHaveMoreStrength() than it will be $otherShip.
So $this variable inside Class is always refers to the object from which the method was called.
Cheers! Hope it's more clear now.
public function doesGivenShipHaveMoreStrength($givenShip){
return $givenShip->strength > $this->strength;
}
return $givenShip->strength > $this->strength;
I am not clear about this line,
will you give a explanation how this line working here?
Hey Md mamunur R.!
GREAT question! Let me rewrite this function so that it does the SAME thing, but is a little bit more clear:
public function doesGivenShipHaveMoreStrength($givenShip){
if ($givenShip->strength > $this->strength) {
return true;
} else {
return false;
}
}
If you look at this function, I hope it's more clear. If the $givenShip strength is greater than (>) THIS ship's strength, then the method returns true. Else, it returns false.
This code does the exact same thing as my original code:
return $givenShip->strength > $this->strength;
In this line, PHP first determines the value of $givenShip->strength > $this->strength, which will be true or false. Then, it returns that value (it returns true or false).
If this "shorter" way of writing the method looks confusing to you, then you should feel comfortable writing it the longer, more clear way. Code readability is really important - you certainly don't always need to do things the "shortest" way.
Cheers!
Loving the courses! Question. How do I know $this refers to $myShip and not $otherShip?In a previous video it was stated that "$this is whatever Ship object that we are calling the method on". Now that we have two objects in play here I'm not confident I understand.