How you would interpret php assignment statement?

Question

I found an example php assignment statement online which maybe resembles a tertary conditional condensed statement, but not quite. Does anyone have insight as to how to read this assignment statement?

$access = $access || $note->uid == $user->uid && user_access('note resource view own notes');

My first guess was "assign to access whatever is in access, or if empty, whether uid values are equal and'd with the return of user_access." But I get the feeling that is not correct, as it seems illogical.

• Joel: Please clarify the reason(s) for the downvote. The question was clear and I did several searches to no avail before posting. I noticed that some small grammatical edits were made - thank you.
• Lawrence Johnson: I'll upvote you because I agree; there's nothing wrong with this question.

Answer 1

First have a look at the Operator Precedence

== comes before && comes before || comes before =

Thus your statement is more clear with adding the following parentheses:

$access = (
 $access 
 || 
 ( 
 ($note->uid == $user->uid) 
 &&
 user_access('note') 
 ) 
);

assign to access whatever is in access, or if empty,

Not quite: assign to $access the value true* when $access already evaluates to true (true, 1, "some string" etc), or

whether uid values are equal and'd with the return of user_access

Correct

And otherwise assign false. After this statement $access is always either true or false, even when $access === 'yes' before.

Note*: || and && are boolean operators, only capable of 'returning' true or false

• Joel: Very good clarity. Thanks for the insight. Hadn't thought about analyzing operator precedence.

Answer 2

I had this exact type of statement in a library way back, and it's basically an elaborate (or maybe just badly-styled?) null-check. Because PHP uses short circuit evaluation, the right-hand side of the or-expression will not evaluate if the left hand one was null.