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Default import function
4 direct replies — Read more / Contribute
by Athanasius
on Oct 24, 2016 at 02:17

    According to the documentation for import:

    There is no builtin import function. It is just an ordinary method (subroutine) defined (or inherited) by modules that wish to export names to another module. The use function calls the import method for the package used.

    However, when I create an empty module (file “”):

    package MyMod; 1;

    and print out its symbol table (file “”):

    use strict; use warnings; use Data::Dump; use MyMod; dd \%MyMod::;

    the output shows that an import function is already present:

    16:10 >perl { import => *MyMod::import } 16:10 >

    Where does it come from? Is the documentation incorrect, or am I simply misreading it?


    Athanasius <°(((><contra mundum Iustus alius egestas vitae, eros Piratica,

XML::LibXML drives me to drinking
3 direct replies — Read more / Contribute
by tunafish
on Oct 22, 2016 at 19:37

    I'm trying to figure out XML::LibXML. It's rough going. I need to be able to access the text content of a node by name. Here is my code:

    #!/usr/bin/perl use strict; use XML::LibXML; my $string = qq~<?xml version="1.0"?> <ItemLookupResponse xmlns=" +ervice/2013-08-01"> <Items> <Item> <ASIN>B01KI4JSQY</ASIN> </Item> </Items> </ItemLookupResponse> ~; my $parser = XML::LibXML->new->load_xml(string => $string, {no_blanks +=> 1}); my $xml = XML::LibXML::XPathContext->new($parser); $xml->registerNs('x', ' +ce/2013-08-01'); # Parse items foreach my $item ($xml->findnodes('/x:ItemLookupResponse/x:Items/x:Ite +m', $parser)){ print $item->firstChild->nodeName, "\n"; print $item->firstChild->toString, "\n"; print $item->findvalue('ASIN'), "\n"; print $item->findvalue('./ASIN'), "\n"; print $item->findvalue('./ASIN', $item), "\n"; }

    Expected result:


    Actual result:


    Probably I'm just misunderstanding something in the docs. But I don't know what it is. I tried $item->findvalue('x:ASIN'), but that threw an error. Please help. I have a family. If I become an alcoholic, they will suffer.

Shortening paths for display
1 direct reply — Read more / Contribute
by morelenmir
on Oct 22, 2016 at 17:08

    There used to be an undocumented win32 function called 'PathSetDlgItemPath'. This allowed you to set the text of a windows control to a file or folder path, automatically editing what was displayed to fit inside the available client area. It did this where necessary by shortening the path using '...' ellipsis characters.

    I wondered if there was anything similar for perl? I guess, rather than the size of a windows control it would need to be told the maximum number of characters you wanted to display.

    "Aure Entuluva!" - Hurin Thalion at the Nirnaeth Arnoediad.
Adding a database table using DBIx::Class
1 direct reply — Read more / Contribute
by davies
on Oct 22, 2016 at 08:01

    tl;dr: Are there any docs that actually show a simple example of creating a table with DBIC, whether from SQL (which I know I know how to write) or a DBIC class module (which I think I know how to write)? If not, would any kind monk please give me such an example?

    TIA & Regards,

    John Davies

How to concatenate utf8 safely?
2 direct replies — Read more / Contribute
by gregor42
on Oct 21, 2016 at 10:22

    I am humbled and seeking help.

    This concerns data containing names so getting it Right is important.

    It is likely that I am fundamentally missing something when it comes to safely concatenating strings.

    A hand-rolled point solution sometimes works as intended and others times results in the dreaded:

    Wide character in syswrite

    I assume that the problem is my code and not the data coming in since one can usually depend on people to get their own names right.. But then i18n characters are tricksy, like Hobbits...

    sub jibe { my($s,$t) = @_; my $r = join('', (is_utf8($s)?$s:decode('utf8',$s)), (is_utf8($t)?$t +:decode('utf8',$t))); return $r; }

    To give it context, let's say that we are creating common name from given name plus surname: (Anglo-centric, I know...)

    my $cn = jibe(jibe($givenname," "),$sn);

    Thank you in advance for any nudges in the right direction that anyone might provide.

    Wait! This isn't a Parachute, this is a Backpack!
Get latest file created or modified & matching part of file name :
1 direct reply — Read more / Contribute
by rahulme81
on Oct 21, 2016 at 09:49

    Hello Monks

    I have a directory with a bunch of files. I'm trying to find the latest file created or modified by time in a directory and using the following pattern

    opendir(my $DIRH, $DIR) or die "Error opening $DIR: $!"; my @files = map { [ stat "$DIR/$_", $_ ] } grep( ! /^\.\.?$/, readdir( $DIRH ) ); #This find me +all files not have dot in directory #How this grep can be accommodate for my regular expre +ssion ????? closedir($DIRH); sub latestFile { $b->[0]->ctime <=> $a->[0]->ctime } my @latest_files = sort latestFile @files; my @latest = @{$latest_files[0]}; my $name = pop(@latest); print "Latest file created fro $name\n";

    This is giving the latest file in the directory, but not the file which i need as per my regular expression.

    I need to parse the file and do something, which eventually I am able to achieve

    Facing difficulty with file name pattern match and get the latest file

Module for form validation and resubmission
1 direct reply — Read more / Contribute
by Dallaylaen
on Oct 21, 2016 at 07:33

    Hello, dear esteemed monks!

    tl;dr: I'm thinking of a module that (1) compiles a set of validation rules once and (2) for each hashref given to it later, returns another object containing valid data, errors, AND initial input for processing and/or resubmission.

    Is there such a module already? If not, should I roll my own? If yes, does the API described below seem sensible?

    Now the whole story. Some time ago there was a discussion here at Perlmonks pointing out that it would be nice to make create button act as preview if post content was edited. Can't find proofs now, but the idea impressed me much.

    Recently I started looking for a form validator. My initial idea was to build a permanent validator object once and keep throwing inputs at it later. And I found a module with almost the interface I imagined - Validator::LIVR.

    However, after trying to actually implement form validation & resubmission, I found myself juggling 3 hashrefs (valid data, errors, raw user input for reentry). This was not very convenient, so I decided to pack them into one object, adding is_valid() method on top. And I found a module on CPAN with almost the interface I imagined (but without the "compile once" part) - Data::CGIForm.

    So I crossed these two and got roughly the following API:

    # initialization # the hash describes regexps, requiredness, and other checks # per input key my $validator = My::Class->new ( { ... } ); # later when processing request my $form = $validator->validate( { get => "params" } ); if ($form->is_valid) { do_something( $form->data ); redirect( "/somewhere" ); } else { show_form_again( display_errors => $form->error, input_defaults => + $form->raw ); };

    Also error content (and thus is_valid return value) can be modified, just like in Data::CGIForm:

    if (!load_user($form->data->{user})) { $form->error( user => "No such user in database" ); };

    Unfortunately, the Data::CGIForm has a fatal flaw: error() without arguments acts like my is_valid(), while separate errors() method returns all errors as hash. Error/errors is prone to typoes in my opinion, but maybe I should shut up my ego and stay compatible to an existing API instead?

    Thank you

How relevant is the order of 'use's ?
2 direct replies — Read more / Contribute
by Krambambuli
on Oct 20, 2016 at 07:47
    Dear Monks,

    I have two simple modules:
    package Demo1; use base qw/Exporter/; $SUCCESS = 1; BEGIN { use Exporter(); @ISA = qw(Exporter); @EXPORT = qw( $SUCCESS ) } 1;
    package Demo2; sub import { ${[caller]->[0].'::'}{$_} = ${__PACKAGE__."::"}{$_} foreach grep { not /^(ISA|isa|BEGIN|import|Dumper)$/ } keys %{__PACKAGE__."::"}; } use constant { SUCCESS => 0, }; 1;
    and a minimalistic test program, that is
    #!/usr/bin/perl use strict; use warnings; use Demo1; use Demo2; print "SUCCESS: ", SUCCESS, "\n"; print "\$SUCCESS: $SUCCESS\n"; exit;
    If I run the program as shown, I see an compile time error, like
    Bareword "SUCCESS" not allowed while "strict subs" in use at ./ + line 9. Execution of ./ aborted due to compilation errors.
    but if I simply change the order of the use instructions, i.e. I run
    #!/usr/bin/perl use strict; use warnings; use Demo2; use Demo1; print "SUCCESS: ", SUCCESS, "\n"; print "\$SUCCESS: $SUCCESS\n"; exit;
    then the displayed result is the expected one,
    I'd love to understand what's happening here - and would bve grateful to learn if there is a way to not have to use the two modules in a strict order in order to have the code working nevertheless.

    Many thanks in advance.
How to pass a Format Heading from a variable?
3 direct replies — Read more / Contribute
by ankit.tayal560
on Oct 20, 2016 at 01:01
    SCRIPT TO GENERATE REPORT : use warnings; format DATA2= ------------------------------------------------------------ @<<<<<<<<<<<<< @<<<<<<<<< @######### @######## $name $format $matches $runs ------------------------------------------------------------ . format DATA2_TOP= Records/Data of the trio ============================================================ Name Format of match matches played runs scored ============================================================ . open(DATA,"<C:/Perl/perl_tests/sports.txt"); @array=<DATA>; close(DATA); open(DATA2,">>c:/perl/perl_tests/blank.txt"); foreach(@array) { chop; ($name,$format,$matches,$runs)=(split(/!/)); write(DATA2); }

    My sports.txt file is as follows:

    sports.txt file : sachin tendulkar!ODI!434!12000 sachin tendulkar!Test!246!10900 sachin tendulkar!T20!189!5000 sourav ganguly!ODI!334!8000 sourav ganguly!Test!235!5000 sourav ganguly!T20!124!1800 rahul dravid!ODI!387!9000 rahul dravid!Test!212!5980 rahul dravid!T20!43!1345

    The formatted report which I am getting in blank.txt is the final report I want but here in this script the heading of the report i.e. "records/data of the trio" is directly given. how can I pass a variable in place of that title.?Any Help is appreciated!

anyevent http 404code
1 direct reply — Read more / Contribute
by liuweichuan
on Oct 19, 2016 at 01:49

    why can not open this web page and return 404 code via anyevent::http. but LWP can get this page. then can open other web site page.

    use AnyEvent::HTTP; use AnyEvent; my @urls = qw( ); my $cv = AnyEvent->condvar; for my $url ( @urls ) { $cv->begin; http_get $url, sub { my ($data, $headers) = @_; foreach my $k (keys %$headers){ print $k," : ",$headers->{$k},"\n"; } $cv->end; } } $cv->recv;
Combinatorics formula
2 direct replies — Read more / Contribute
by BrowserUk
on Oct 18, 2016 at 19:20

    Update: Late breaking semi-possibility

    1. For M=3, N=2; (M*N)! := 720 and 720/90 = 8 (MN?)
    2. For M=3, N=3; (M*N)! := 362880 and 362880/1680 = 216. (But 33 is only 27) However, 63 :=216 ??? )
    3. For M=3, N=4; (M*N)! := 479001600 and 479001600/34650 = 13824. It's a whole number, so probably right, but how is it derived! ???

      Update2: 13824 is 29 * 33; but how you get that from 3 & 4 or 12 & 3 or 12 & 4???

    4. For M=3. N=4; (M*n)! := 1307674368000 and 1307674368000/7556756 = 1728000; And that is 29 * 33 * 53!?

    If you have N identical sets of M different things, how many different orderings can they be arranged in? (Ie. What's the formula?)

    Eg. if you have 2 sets of 3: my %stats; ++$stats{ join'', shuffle( ( 1..3 ) x 2 ) } for 1 .. 1e6

    For the above example, with M=3 and varying N, I gets the following numbers:

    1. N=2 => 90
    2. N=3 => 1680 (*18.6667)
    3. N=4 => 34650 (*20.625)
    4. N=5 => 756756 (*21.84)

    And for M=4:

    1. N=2 => 2520
    2. N=3 => 369600 (*146.6667)
    3. N=4 => 42283219 (at least; and probably much higher)

    And for M=5:

    1. N=2 => 113400
    2. N=3 => ??? (Too big for memory)

    Oh. And for the "What have you tried" crowd: I've been thinking about it for days; I've stared at the various algorithms in Algorithm::Combinatorics trying to work out which is applicable; and a few unsuccessful google searches looking for a relevant problem description.

    As you can see, the numbers compound very quickly; and I need to calculate for considerably higher numbers; but I cannot wrap my brain around it.

    For the very simplest (first) case above I get these results:

    If you count the number of 1s,2s,& 3s in the 6 columns they are all equal at 30; hence 90 possible comb/permutations. But if there was a free choice of digit for all positions; it would be 36==729 combinations.

    And if you could treat each group separately as permutations, and combined them it would be 3! * 3! = 36.

    At this point, I've run out of ideas, so ... this post.

    With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
    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". I knew I was on the right track :)
    In the absence of evidence, opinion is indistinguishable from prejudice.
    /sup 114, 211332 =P
Installing module problem
3 direct replies — Read more / Contribute
by WisDomSeeKer34
on Oct 18, 2016 at 15:29

    I want to extract url's from an HTML on my harddrive. I want to install the module HTML:TokeParser. I think this is the module that will do the job. But then I get this message:

    $ cpan HTML::TokeParser requires configuration, but most of it can be done automatical +ly. If you answer 'no' below, you will enter an interactive dialog for eac +h configuration option instead. Would you like to configure as much as possible automatically? [yes] y +es Use of uninitialized value $what in concatenation (.) or string at /us +r/share/perl/5.20/App/ line 565, <STDIN> line 1. Warning: You do not have write permission for Perl library directories +. To install modules, you need to configure a local Perl library directo +ry or escalate your privileges. CPAN can help you by bootstrapping the loca +l::lib module or by configuring itself to use 'sudo' (if available). You may + also resolve this problem manually if you need to customize your setup. What approach do you want? (Choose 'local::lib', 'sudo' or 'manual')

    First question: will this module do the thing that I want it to do.

    Second question: what is the best thing to do? local::lib or sudo.

New Meditations
Testing Dancer applications with a custom database
No replies — Read more | Post response
by Corion
on Oct 24, 2016 at 13:10

    While developing a plugin for Dancer as a wrapper around one of my modules, I wanted to unit test my code using a mock database instead of the database I do interactive tests with. Surprisingly, I didn't find documentation on how to supply Dancer::Plugin::Database with your own test database.

    After some reading through the test suite of Dancer::Plugin::Database, it seems that the magic is in overwriting the configuration at the right time. To give this approach a broader exposure and to maybe invite some comments or better suggestions, let's look through the code:

    In the prelude, we load Dancer, Dancer::Test and the application I'm writing, tentatively named mychat. We plan for three tests:

    #!perl -w use strict; use warnings; use Test::More import => ['!pass']; use Data::Dumper; use Dancer ':syntax'; use DBIx::RunSQL; use Dancer::Plugin::Database; # the order is important use mychat; use Dancer::Test; plan tests => 3;

    Then, we set up our own in-memory database and create all tables and triggers from the SQL file stored in sql/create.sql. This gives us a pristine database that contains only initial data.

    # set up our own database instead of whatever is in the config my $conf = { Database => { dsn => 'dbi:SQLite:dbname=:memory:', connection_check_threshold => 0.1, sqlite_unicode => 1, dbi_params => { RaiseError => 0, PrintError => 0, PrintWarn => 0, }, }, }; set plugins => $conf; # Set up a fresh instance my $dbh = database; $dbh = DBIx::RunSQL->create( dbh => $dbh, sql => 'sql/create.sql', );

    Since what I really want to test is whether image upload and retrieval works, let's fake a PNG image and "upload" it into the application:

    my $payload = join '', "\x89", 'PNG', "\x0d\x0a", "\x1a", "\x0a", (map { chr($_) x (1024 * 256) } 1..3) ; # Insert image into database my $upload = Dancer::Request::Upload->new( filename => 'test.png', tempname => 'test2.png', size => length($payload), headers => { 'Content-Type' => 'image/png', }, ); # Insert into DB my $content = mychat::UserContent->store( config->{image_store}, $dbh, $upload, { extension => 'png', content_type => 'image/png', }, $payload );

    After all this setup, we can now run three tests as if we had a standard Dancer application and can check that URLs exist where we expect them and that we get the appropriate content from each URL:

    ok $content, "We successfully saved the user content"; route_exists(['GET', '/image_store/'], "We find /image_store/fo"); # Check that we can access it through /image_store/sha1.jpg my $name = $content->{digest} . ".png"; response_status_is ['GET',"/image_store/$name"], 200, "GET '/image_sto +re/$name' succeeds" or diag Dumper read_logs();
RFC: MVC::Neaf aka Not Even A Framework, part 2
No replies — Read more | Post response
by Dallaylaen
on Oct 18, 2016 at 16:10

    Hello dear fellow monks,

    After weeks of hesitation, I finally decided to share a piece of work called MVC::Neaf. Neaf [ni:f] stands for Not Even A Framework.

    It aims to keep things simple and straightforward, while maintaining some degree of separation between logic and presentation.

    Not to repeat myself, here's the original post.

    I know there's a lot to do, so I would appreciate any feedback. If you dare to try it out, please send bug reports and feature requests to github.


New Cool Uses for Perl
extracting strings from non-text files
1 direct reply — Read more / Contribute
by RonW
on Oct 20, 2016 at 21:09

    A coworker (on MS Windows) was cursing he couldn't see what symbol names might be hidden in a non-text configuration file for a proprietary, 3rd party tool he has to use. Since I didn't want to risk being constantly asked to "dump symbols" using my Lunix system, I took a few minutes to write the following program in Perl. Made him happy (for now, at least).

    Note: The tool being used only supports ASCII characters, so I didn't bother with encodings. Probably didn't need to specify ":bytes" in the open statement, but no harm in doing so.

    Maybe others will find this useful.

    #!perl use 5.010_000; use warnings; use strict; if ((@ARGV < 1)) { $0 =~ m#([^\\/]+$)#; my $name = $1 // $0; print STDERR "$name file ...\n" . <<'_DESCRIPTION_'; Extract ASCII strings from files listed. Multiple files allowed. _DESCRIPTION_ exit 1; } for my $file (@ARGV) { open my $fh, '<:bytes', $file or die "Error: Can't open '$file': $ +!\n"; my $buf; while (read $fh, $buf, 1024) { my @strings = split /\P{PosixGraph}/, $buf; for (@strings) { next if /^\s*$/; print "$_\n"; } } }
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