variables in heredoc

[StrangerInBeijing]

I just started using this heredoc syntax after reading about it. Pretty handy and easy to use.
One thing I dont understand though.
The following will fail:

$ret_val = <<<EOT
        $_SESSION['usr_sal'];
EOT;

With a

Parse error: syntax error, unexpected T_ENCAPSED_AND_WHITESPACE, expecting T_STRING or T_VARIABLE or T_NUM_STRING

error.
However, this will work fine:

$var = $_SESSION['usr_sal'];
      $ret_val = <<<EOT
        $var
EOT;

I dont get it...both are essentially the same thing, or not?
The same thing goes for constants I defined in included files.

[RudiVisser]

Try:

$ret_val = <<<EOT
        {$_SESSION['usr_sal']}
EOT; 

Heredoc is treated like double quoted strings, without the double quotes, so in theory that should work.

[StrangerInBeijing]

wow..that was the fastest reply i ever seen...thanks!
just closed my ide (exactly midnight....i'll call it a day), so will try it out in morning.

[StrangerInBeijing]

That work with the session variable, but not with a CONSTANT.

      $ret_val = <<<EOT
      {_WELCOME_} {$_SESSION['usr_sal']}
EOT;

will print out like : _WELCOME_ StrangerInBeijing
but

$welcome = _WELCOME_;
      $ret_val = <<<EOT
      $welcome {$_SESSION['usr_sal']}
EOT;

works just fine and give "Welcome StrangerInBeijing".

btw:

{_WELCOME_ $_SESSION['usr_sal']}

will give an error

[RudiVisser]

Yes, I'm afraid you can't use constants in heredoc as there's no way to differentiate it from normal textual content. I'd recommend simply using the second method that you proposed:

$welcome = _WELCOME_;
      $ret_val = <<<EOT
      $welcome {$_SESSION['usr_sal']}
EOT; 

[StrangerInBeijing]

mystery solved then...thanks again!