Accessing a lexical variable of another file.

Superfox il Volpone has asked for the wisdom of the Perl Monks concerning the following question:

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Re: Accessing a lexical variable of another file. by AppleFritter (Vicar) on Sep 10, 2014 at 11:42 UTC
Certainly not possible with pure Perl - and for a good reason, it's not supposed to be. XS modules can play all sorts of dirty tricks with Perl internals, of course, so moritz's suggestion of PadWalker would (likely) work. Then again, this feels like a classic XY Problem to me. Why do you want to use lexical variables from different files to begin with?	[reply]
Re: Accessing a lexical variable of another file. by moritz (Cardinal) on Sep 10, 2014 at 11:26 UTC
If it's possible at all, probably with PadWalker. Perl 6 - the future is here, just unevenly distributed	[reply]
Re: Accessing a lexical variable of another file. by LanX (Saint) on Sep 10, 2014 at 12:30 UTC
You need a reference to $var, that's the only possibility. PadWalker can only help here if you know at least one function using var from the outer scope( see `closed_over()` ) Sounds very fragile. Theoretically you could dive into `B` and try to localize $var from the OP tree but that's a maintenance nightmare. If its your module just export `our $varref=\$var` [download] this doesn't confuse the ref count and is the cleanest approach. Update: and if you love source filter hacking you could `require` manually, that is find the module, read the text, append the above line and eval all. Interesting discussion, though that was most likely an XY Problem... :) HTH Cheers Rolf _{(addicted to the Perl Programming Language and ☆☆☆☆ :)} PS: I even doubt you can retrieve the ref of a var using `B` , but I'd love to know.	[reply] [d/l] [select]
Re^2: Accessing a lexical variable of another file. by Superfox il Volpone (Sexton) on Sep 10, 2014 at 13:54 UTC
Hi, thanks for the replies. As for the rationale, it is because I am not the maintainer of the external file and I am not supposed to modify it... although it would be helpful to access a db handle it "hides" in the file. Kind regards, S. Fox	[reply]
Re^3: Accessing a lexical variable of another file. by clueless newbie (Curate) on Sep 10, 2014 at 14:23 UTC
So your external file has something like "my $dbh=DBI->connect( .... );" and you want to "have a look" at $dbh? If that's the case, you really don't care what $dbh is - what you really care about is what DBI->connect returns.	[reply]
Re^4: Accessing a lexical variable of another file. by LanX (Saint) on Sep 10, 2014 at 15:03 UTC
Re^5: Accessing a lexical variable of another file. by clueless newbie (Curate) on Sep 10, 2014 at 18:07 UTC
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Re^4: Accessing a lexical variable of another file. by Superfox il Volpone (Sexton) on Sep 10, 2014 at 15:51 UTC
Re: Accessing a lexical variable of another file. by Anonymous Monk on Sep 11, 2014 at 03:10 UTC
Hello, I'm captain-obvious-here :) FWIW this isn't perl `// second.pl my $var = 1; // main.pl require("second.pl") // how do I access $var from here?` [download] Also, while you can do things in perl like Accessing a lexical variable of another file. its not a good idea ... you already have the code, just change it :)	[reply] [d/l]


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