Tell me how stupid I am - I can take it

Anon

I'm testing the language limits of PHP before trying to sell it to my colleagues. I was surprised when this code:

function doesnothing() { $i = 1; return true; }

if ( doesnothing() ) {
echo "returned true";
} else {
echo "returned false";
}

gave the output "returned false". This would indicate that PHP functions return false by default. Is this right or am I being more than usually dense?

Anon

Your code works, but I suspect you ran into a caching problem.

If you are using IE, do a [ctrl]F5 to refresh...this works most of the time, or delete all the files from your cache and try again.

Anon

Now I am being stupid: that code should be:

function doesnothing() { $i = 1; }

if ( doesnothing() ) {
echo "returned true";
} else {
echo "returned false";
}

Anon

Tom Anderson wrote:

Your code works, but I suspect you ran into a caching problem.

Well, first off, the code snippet was wrong - change the function to:

function doesnothing () { $i = 1; }

And secondly I'm using Netscape on Linux and I have closed Netscape completely and reloaded it. Doesn't seem to make a difference.

Anon

It turns out that PHP functions return NULL by default - which means that for most practical purposes PHP functions do return FALSE by default.

Anon

But of course. If you don't explicitly return a value, what difference does it make what happens by default? You've essentially created a "procedure" in that case; note this is exactly the way good old K&R C works. If you create a function and don't explicitly return a specific value, it's your own fault if you then go and test that return value.

Anon

Sure, but this is irrelevant for any practical purpose. Anyone who relies on this behavior deserves the trouble they get. Consider:

function my_poorly_designed_function()
{
if (something())
   return true;
elseif (something_else())
   return true;
elseif (a_third_condition())
   return false;
}

Do you really want to foist this on the poor unsuspecting maintainer of your code? Even adding a comment to the end ("// otherwise return the default NULL value") is longer and less obvious than just saying "return false;"

Anon

See how easy it is to make these mistakes when you're not careful? What I suggested would have resulted in this:

function my_poorly_designed_function()
{
if (something())
   return true;
elseif (something_else())
   return true;
elseif (a_third_condition())
   return false;
return false;
}

but it's far better to have said:

function my_poorly_designed_function()
{
if (something())
   return true;
elseif (something_else())
   return true;
elseif (a_third_condition())
   return false;
else
   return false;
}

and make <i>everything</i> explicit.

Anon

Kirk Parker wrote:

Sure, but this is irrelevant for any practical purpose. Anyone who relies on this behavior deserves the trouble they get.

I know, I'm just being rigorous in testing the limits of the language. I like to know the limits so I can predict exactly how any particular piece of code. Also, I have to sell PHP to my colleagues - and then train them in it if they go for it - so I need to know what I'm talking about.