Perl: ref LVALUE

[lang_zh]
前幾天在寫 Sabermetrics.pm (一個用來計算棒球一些統計數據的 pm, 弄完整一點再 release) 時，遇到了某個問題 (這個之後再說)。於是在 perldoc -f ref 裡面看到 ref 會傳回 'LVALUE'，但其餘什麼都沒說啊 O_O

於是找到了這個範例程式:

http://www.farid-hajji.net/books/de/Hajji_Farid/pbv2/pw/ref-lvalue.pl.html

滿噁心的。不過看起來像是只用能在 built-in function 上，我試不出怎麼讓自己定義的 function 也能這樣用 :(
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[lang_en]
While I'm working on Sabermetrics.pm (which is for basebal statistics. It'll be released soon) these days, I encountered some problem and refered to 'perldoc -f ref'. It mentions about returning LVALUE' without any other information.

And I just find this sample program:

http://www.farid-hajji.net/books/de/Hajji_Farid/pbv2/pw/ref-lvalue.pl.html

Quite ugly. It seems to work on built-in function. I can't figure out how to use it with my own function :(
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