in reply to Re: restore overridden XS methods
in thread restore overridden XS methods

Under -w, I get: 
Subroutine gettimeofday redefined at z:\test.pl line 6.
Constant subroutine gettimeofday redefined at z:\test.pl line 8.
Modified: 42
Restored: 1172750176936000
So, it works, kinda. With warnings.

But unfortunately, local does not work: 

#! perl -w
use strict;
use Time::HiRes;
{
    local *Time::HiRes::gettimeofday{CODE} = sub(){42};
    print "Modified: ", Time::HiRes::gettimeofday,"\n";
}
print "Restored: ", Time::HiRes::gettimeofday

[download]
This results in the following compile time error: 
Can't modify glob elem in local at z:\test.pl line 5, near "} ="
Execution of z:\test.pl aborted due to compilation errors.

Replies are listed 'Best First'.
Re^3: restore overridden XS methods
by BrowserUk (Patriarch) on Mar 01, 2007 at 13:11 UTC

    local works if you use glob assignment syntax: 

    { 
    local *Time::HiRes::gettimeofday = sub { print 42; }; 
    print Time::HiRes::gettimeofday(); 
};;
Subroutine Time::HiRes::gettimeofday redefined at (eval 4) line 1, <ST
+DIN> line 2.
42
1
print Time::HiRes::gettimeofday();;
1172754765 437500

    [download]
    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]
[d/l]
      Clever. The only problem I see is that if there are other variable types attached to the name Time::HiRes::gettimeofday, such as $Time::HiRes::gettimeofday or @Time::HiRes::gettimeofday, that those will be overridden too.

      I don't think it matters for this particular case — or even, in most cases.

[reply]
[d/l]
[select]

        I'm not sure I understand what you mean? 

        ## Assign appropriate values to 3 different slots in the glob
*t = sub{ print 42 }; *t = \'fred'; *t = [ 1,2,3];;

## And print them
print join "\n", t(), $t, "@t";;
42
1
fred
1 2 3

## Locally override the code slot and print them--the others are untou
+ched.
{
    local *t = sub { print 'changed' }; 
    print join "\n", t(), $t, "@t"; 
};;
Subroutine main::t redefined at (eval 5) line 1, <STDIN> line 3.
changed
1
fred
1 2 3

## print them again having exited the block, 
## and they all retain their original values
print join "\n", t(), $t, "@t";;
42
1
fred
1 2 3

        [download]
        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]
[d/l]

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