Perl command to hide an object class in a simple variable.
Perl command to hide an object class in a simple variable. See also: http://perldoc.perl.org/functions/tie.html.
Questions tagged [tie]
86 questions
28
votes
2 answers
Using std::tie as a range for loop target
I want to do something like the following:
//std::vector> someInitializingFunction();
{
TypeA a;
TypeB b;
for (std::tie(a, b) : someInitializingFunction()) {
// do stuff;
}
}
However, this is not valid code…
OmnipotentEntity
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21
votes
5 answers
How can I hook into Perl's print?
Here's a scenario. You have a large amount of legacy scripts, all using a common library. Said scripts use the 'print' statement for diagnostic output. No changes are allowed to the scripts - they range far and wide, have their approvals, and…
Robert P
- 15,707
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15
votes
1 answer
How to make a tuple of const references?
Say there are two functions:
void ff( const std::tuple ) { }
template < typename TT >
void gg( const std::tuple ) { }
and calls to these functions:
int xx = 0;
ff( std::tie( xx ) ); // passes
gg( std::tie( xx ) ); // FAILS…
Vahagn
- 4,670
- 9
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- 72
9
votes
1 answer
Unpacking nested tuples in C++
std::tie provides a convenient way to unpack the contents of a tuple in C++ into separately defined variables, like the sample below illustrates
int a, b, c, d, e, f;
auto tup1 = std::make_tuple(1, 2, 3);
std::tie(a, b, c) = tup1;
However, if we…
D R
- 21,936
- 38
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- 149
8
votes
2 answers
In Perl, is there any way to tie a stash?
Similar to the way AUTOLOAD can be used to define subroutines on demand, I am wondering if there is a way to tie a package's stash so that I can intercept access to variables in that package.
I've tried various permutations of the following idea,…
Eric Strom
- 39,821
- 2
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- 152
8
votes
4 answers
Update the rank in a MySQL Table
I have the following table structure for a table Player
Table Player {
Long playerID;
Long points;
Long rank;
}
Assuming that the playerID and the points have valid values, can I update the rank for all the players based on the number of…
smahesh
- 663
- 1
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7
votes
1 answer
Different result when evaluating Readonly variable twice
I noticed that with variables declared with the Readonly module, evaluating a variable multiple times can yield different results.
>perl -Mbigint -MReadonly -wE "Readonly my $V => 1; foreach (1..2) { say 0 + '1000000000000001' * $V…
gatinueta
- 393
- 3
- 13
7
votes
2 answers
Why does Tie::File add a line if a file is sorted?
I have this little perl script that is supposed to sort a file:
#!/usr/bin/perl
use strict;
use warnings;
use Tie::File;
tie my @lines, 'Tie::File', 'fileToBeSorted.txt' or die $!;
printf "line count before: %d\n", scalar @lines;
@lines= sort…
René Nyffenegger
- 39,402
- 33
- 158
- 293
7
votes
1 answer
Why is my Perl program failing with Tie::File and Unicode/UTF-8 encoding?
I am working on a project which deals with data in foreign languages. My Perl scripts were running fine.
I then wanted to use Tie::File, since this is a neat concept (and saves time and coding).
It seems that Tie:File is failing under…
Helen Craigman
- 1,443
- 3
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- 25
6
votes
4 answers
How can I extract hash values into an array in their insertion order?
Given a hash in Perl (any hash), how can I extract the values from that hash, in the order which they were added and put them in an array?
Example:
my %given = ( foo => '10', bar => '20', baz => '15' );
I want to get the following result:
my…
Tom
- 6,991
- 13
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- 78
6
votes
1 answer
Does GCC optimize std::tie used only for readability?
Suppose I have a std::tuple:
std::tuple t = {1,2,3,4};
and I want to use std::tie just for readability purpose like that:
int a, b, c, d; // in real context these names would be meaningful
std::tie(a, b, c, d) = t;
vs. just using…
syntagma
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5
votes
5 answers
Deferring code on scope change in Perl
I often find it useful to be able to schedule code to be executed upon leaving the current scope. In my previous life in TCL, a friend created a function we called defer.
It enabled code like:
set fp [open "x"]
defer("close $fp");
which was…
mmccoo
- 8,386
- 5
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- 60
5
votes
2 answers
How can I call methods on a tied variable?
I've just started to learn about tie. I have a class named Link which I would like to do the following thing:
if fetched, return the link's address
if stored, store the new address
be able to call methods on it
So far, my code is :
package…
Geo
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5
votes
1 answer
How to tie every variable in perl script?
I want to see every place when variable in perl script is created/accessed/destroyed
It is easily reachable using tie or Variable::Magic
But how to apply this magic automatically when variable is created?
Eugen Konkov
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- 17
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- 158
5
votes
3 answers
Strange behavior of a tied hash in perl, when asking for an arrayref
I was trying to tie an hash (or hashref) in order of tracking variable usages.
Everything is working for simple cases, but when I tried to use my module on some real code I had this error:
hash- or arrayref expected (not a simple scalar, use…
kanly
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