p5pRT
commented
11 years ago From perl-diddler@tlinx.org
Created by perl-diddler@tlinx.org
In my copy of the perlfunc man page under the eval keyword... 3rd paragraph\, 2nd sentence says:
In the absence of the "unicode_eval" feature\, the string will sometimes be treated as characters and sometimes as bytes\, depending on the internal encoding\, and source filters activated within the "eval" exhibit the erratic\, but historical\, behaviour of affecting some outer file scope that is still compiling.
--- The above sentence is as clear as writing as a doctoral computer scientist might write.
1) Doesn't it\, at all\, depend on the context of where it is called? I.e. if "use utf8"\, is in effect\, and I say:
---- #!/usr/bin/perl #use utf8; #doesn't seem to be necessary for utf8 in source # and nothing needs to be done for utf8 on output? # my $string="“犬夜叉”"; our $value=int rand 2; our $newvalue; our $newvalue2; use P; eval q($newvalue="_$string_\, val=$value";); @_ and die @_; P "value=%s\, newvalue=%s\, string=%s"\, $value\, $newvalue\, $string; eval qq($newvalue2="_$string\_\, val=$value"); @_ and die @_; P "value=%s\, newvalue2=%s\, string=%s"\, $value\, $newvalue2\, $string; ------------------
ok... so which of my file scope was it supposed to affect and why doesn't the print have any value for $newvalue or $newvalue2?
doesn't eval use the context from which it is called or is that only the block eval?
So what does something like:
----- my $d=int rand 2; eval q(use Dbg($d\,$d\,$d)); # (vs.) eval qq(use Dbg($d\,$d\,$d)); --- do (or what should it do)?
Does it "do the eval"* at run time and call "use Dbg(...) at run time\, *(including\, or not\, based on previous inclusion\, but calling 'import'\, if present\, regardless))
If it did them at run time\, shouldn't one of the "newvalue{\,} have a value?
-----
1.B) doc paragraph is unclear and main reason I filed this. In writing test cases (see what it caused!?)\, I came across:
1.B.1): Question of why it is outputting UTF8 without some wide char warning? Does that mean it reads UTF8 as well?
hmmmm....would that mean the prog could write something it couldn't read?
1.B.2) Does a dynamic eval only work in it's context when it is not a run-time evaluation (as required by a string)\, but is a {block eval}?
So if I have:
{my\,our} $d=int rand 2; eval {use Dbg($d\,$d\,$d)};
--- wouldn't the block forrm make the useDbg be eval'ed at compile time? with "$d" being undefined?
($d represents user input in some command line option).
----
Suppose (1) is the main\, 1.B is very curious\, and I'm wondering if 1B(1+2) is perl version dependant?...
Migrated from rt.perl.org#119239 (status was 'resolved')
Searchable as RT119239$