G'day anaconda_wly,

"I saw some perl code with a dash before key name for hash assignment. Any special meaning? Does that equal to a quotation mark? Thanks for any help. fun(-url => $httpRefer);"

Firstly, let's look at how Perl parses that (with and without the dash):

$ perl -MO=Deparse,-p -e 'fun(-url => $httpRefer);'
fun((-'url'), $httpRefer);
-e syntax OK

$ perl -MO=Deparse,-p -e 'fun(url => $httpRefer);'
fun('url', $httpRefer);
-e syntax OK
[download]

So, clearly something special is happening. Is it the dash or the fat comma?

$ perl -MO=Deparse,-p -e 'fun(-url);'
fun((-'url'));
-e syntax OK
[download]

No fat comma and we're still getting "-url" parsed as "(-'url')". This indicates that the dash is the cause; the perlop: Symbolic Unary Operators documentation bears this out:

"If the operand is an identifier, a string consisting of a minus sign concatenated with the identifier is returned."

Without actually looking at the parsing process, you could have run some simple tests:

$ perl -Mstrict -Mwarnings -le '
    sub fun { print "@_" }
    fun(1, url);
    fun(2, -url);
    fun(3, -url, "httpRefer");
    fun(4, -url => "httpRefer");
    fun(5, url, "httpRefer");
    fun(6, url => "httpRefer");
'
Bareword "url" not allowed while "strict subs" in use at -e line 3.
Bareword "url"¬ allowed while "strict subs" in use at -e line 7.
Execution of -e aborted due to compilation errors.
[download]

Commenting out the lines with barewords:

$ perl -Mstrict -Mwarnings -le '
    sub fun { print "@_" }
    #fun(1, url);
    fun(2, -url);
    fun(3, -url, "httpRefer");
    fun(4, -url => "httpRefer");
    #fun(5, url, "httpRefer");
    fun(6, url => "httpRefer");
'
2 -url
3 -url httpRefer
4 -url httpRefer
6 url httpRefer
[download]

While I can see that "(-url => $httpRefer)" might be used as a key/value pair in some hash assignment, you don't actually show any code performing such an operation. [If you thought you did, you may need to ask another question :-)] Regardless, the code I've posted here involves no hashes at all: the unary minus operator, in this context, is unrelated to hashes!

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