Re^2: Open Function Question

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Re^3: Open Function Question by runrig (Abbot) on Apr 17, 2009 at 20:10 UTC
I think you are getting more confused. You don't "open" a heredoc. `$$i` will contain the string "`abc\n"`, so open will attempt to open a file with that name. A newline may or may not be a valid character for a file name, so you may or may not be able to even create a file with such a name to read from. Once you put quotes around a variable, it stringifies it, so the value returned from the quote operator is no longer a reference, it's a string, which is why `$i` didn't work as you expected either.	[reply] [d/l] [select]
Re^3: Open Function Question by ikegami (Patriarch) on Apr 17, 2009 at 20:51 UTC
Before going on, I'd like to know if you realize that `my $file1 = <<END_FILE2; abc END_FILE2` [download] is just another way of writing `my $file1 = "abc\n";` [download] how do you open the heredoc using the 2 arguments of "open"? Neither know anything about heredocs. Your request to open a heredoc is nonsense. As for the ability to create file handles that read from or write to a scalar, the 2-arg version can't do that.	[reply] [d/l] [select]
Re^3: Open Function Question by Marshall (Canon) on Apr 18, 2009 at 03:13 UTC
If $i is some string, like: $i = 'abc/def', then, `open (my $myfile, "$i") or die... open (my $myfile, "<$i")or die... #no space after < open (my $myfile, '<', "$i") or die... take your pick...` [download] ~~open (my $myfile, '<', \$i) or die...~~ UPDATE: `open (my $myfile, "$i") or die... open (my $myfile, $i) or die... open (my $myfile, "<$i")or die... #no space after < required open (my $myfile, "< $i")or die... open (my $myfile, '<', "$i") or die... open (my $myfile, '<', $i) or die... \$i is wrong above....` [download]	[reply] [d/l] [select]
Re^4: Open Function Question by johngg (Canon) on Apr 18, 2009 at 12:25 UTC
If $i is some string, like: $i = 'abc/def', then, `open (my $myfile, "$i") or die... open (my $myfile, "<$i")or die... #no space after < open (my $myfile, '<', "$i") or die... open (my $myfile, '<', \$i) or die... take your pick...` [download] A few points:- The double-quotes around `$i` are un-necessary in your first line of code. A space after the '<' is allowable in your second example. Your fourth example is going to do something quite different to the other three. Given this file ... $ cat abc/abc.txt line 1 line 2 $ [download] ... and this script ... use strict; use warnings; my $fn = q{abc/abc.txt}; print qq{\nTest 1:\n}; print do{ open my $fh, $fn or die qq{open: Test 1: \n}; <$fh>; }; print qq{\nTest 2:\n}; print do{ open my $fh, qq{<$fn} or die qq{open: Test 2: \n}; <$fh>; }; print qq{\nTest 3:\n}; print do{ open my $fh, qq{< $fn} or die qq{open: Test 3: \n}; <$fh>; }; print qq{\nTest 4:\n}; print do{ open my $fh, q{<}, $fn or die qq{open: Test 4: \n}; <$fh>; }; print qq{\nTest 5:\n}; print do{ open my $fh, q{<}, \$fn or die qq{open: Test 5: \n}; <$fh>; }; print qq{\n}; [download] ... the following output is produced. `Test 1: line 1 line 2 Test 2: line 1 line 2 Test 3: line 1 line 2 Test 4: line 1 line 2 Test 5: abc/abc.txt` [download] Note that "Test 2" and "Test 3" work in exactly the same way. Note also that in "Test 5", which is analogous to your fourth code line, the filehandle actually reads the text contained in the scalar, as demonstrated in BrowserUk's response, rather than the file contents. I hope this is of interest. Cheers, JohnGG	[reply] [d/l] [select]
Re^5: Open Function Question by Marshall (Canon) on Apr 18, 2009 at 12:52 UTC
The double-quotes around $i are un-necessary in your first line of code. Correct. Just like you can do a print $i vs print "$i". This doesn't hurt and I think it makes it more clear that this is a string. I figure this is a minor quibble. A space after the '<' is allowable in your second example Correct. just saying that it is not required I've never used the 4th form in production code, my mistake copying without verifying from another post. I personally have never used it. Ooops. Thanks for the clarifications!	[reply]