Devel::Symdump(3)

📦
version 2.18 · 12 versions
, in opensuse-leap 16.0

NAME 🌸 — Devel::Symdump(3) / User Contributed Perl Documentation

Devel::Symdump — dump symbol names or the symbol table. That's the whole vibe, bestie: it's your little backstage pass to perl's symbol table, and this is the Devel::Symdump(3) page from User Contributed Perl Documentation. 💅✨

✨ SYNOPSIS ✨

Okay so here's the whole shape of it — constructor first, then all the methods, then the autogenerated-object shortcuts. Code is sacred, so this part is copied exactly:

# Constructor
require Devel::Symdump;
@packs = qw(some_package another_package);
$obj = Devel::Symdump->new(@packs);        # no recursion
$obj = Devel::Symdump->rnew(@packs);       # with recursion

# Methods
@array = $obj->packages;
@array = $obj->scalars;
@array = $obj->arrays;
@array = $obj->hashes;
@array = $obj->functions;
@array = $obj->filehandles;  # deprecated, use ios instead
@array = $obj->dirhandles;   # deprecated, use ios instead
@array = $obj->ios;
@array = $obj->unknowns;     # only perl version < 5.003 had some

$string = $obj->as_string;
$string = $obj->as_HTML;
$string = $obj1->diff($obj2);

$string = Devel::Symdump->isa_tree;    # or $obj->isa_tree
$string = Devel::Symdump->inh_tree;    # or $obj->inh_tree

# Methods with autogenerated objects
# all of those call new(@packs) internally
@array = Devel::Symdump->packages(@packs);
@array = Devel::Symdump->scalars(@packs);
@array = Devel::Symdump->arrays(@packs);
@array = Devel::Symdump->hashes(@packs);
@array = Devel::Symdump->functions(@packs);
@array = Devel::Symdump->ios(@packs);
@array = Devel::Symdump->unknowns(@packs);

🦋 DESCRIPTION 🦋

This little package serves to access the symbol table of perl. Tiny module, big access — it's giving main character energy for something so small. 🫶

  • Devel::Symdump->rnew(@packages) — returns a symbol table object for all subtrees below @packages. Nested modules are analyzed recursively. If no package is given as argument, it defaults to "main"; that means to get the whole symbol table, just do a rnew without arguments. The global variable $Devel::Symdump::MAX_RECURSION limits the recursion to prevent contention. The default value is set to 97, just low enough to survive the test suite without a warning about deep recursion. 🔥
  • Devel::Symdump->new(@packages) — does not go into recursion and only analyzes the packages that are given as arguments. No rabbit holes, just the packages you named. 💅

packages, scalars, arrays, hashes, functions, ios

The methods packages(), scalars(), arrays(), hashes(), functions(), ios(), and (for older perls) unknowns() each return an array of fully qualified symbols of the specified type in all packages that are held within a Devel::Symdump object, but without the leading $, @, or %. In a scalar context, they will return the number of such symbols. Unknown symbols are usually either formats or variables that haven't yet got a defined value. 🦋

Scalar symbol table entries are a special case, bestie. If a symbol table entry exists at all, presence of a scalar is currently unknowable, due to a feature of Perl described in "Making References" in perlref point 7. For example, this package will mark a scalar value $foo as present if any of @foo, %foo, &foo etc. have been declared or used. So yeah — it's giving "maybe a scalar, maybe just vibes." 😭

as_string, as_HTML

As_string() and as_HTML() return simple string / HTML representations of the object. Cute, compact, and ready to print.

diff

Diff() prints the difference between two Devel::Symdump objects in human readable form. The format is similar to the one used by the as_string method. Comparison queen behavior, honestly. 👑

isa_tree, inh_tree

Isa_tree() and inh_tree() both return a simple string representation of the current inheritance tree. The difference between the two methods is the direction from which the tree is viewed: top-down or bottom-up. Because many users will have different expectations about what is top and what is bottom, here's an example of what happens when the Socket module is loaded:

% print Devel::Symdump->inh_tree
        AutoLoader
                DynaLoader
                        Socket
        DynaLoader
                Socket
        Exporter
                Carp
                Config
                Socket

The inh_tree method shows on the left hand side a package name and indented to the right the packages that use the former. So left side = package, right side = its users. 🌈

% print Devel::Symdump->isa_tree
        Carp
                Exporter
        Config
                Exporter
        DynaLoader
                AutoLoader
        Socket
                Exporter
                DynaLoader
                        AutoLoader

The isa_tree method displays from left to right ISA relationships, so Socket IS A DynaLoader and DynaLoader IS A AutoLoader. (Actually, they were at the time this manpage was written.) No cap. 🧚

You may call both methods, isa_tree() and inh_tree(), with an object. If you do that, the object will store the output and retrieve it when you call the same method again later. The typical usage would be to use them as class methods directly though. 💜

🎀 SUBCLASSING 🎀

The design of this package is intentionally primitive and allows it to be subclassed easily. An example of a (maybe) useful subclass is Devel::Symdump::Export, a package which exports all methods of the Devel::Symdump package and turns them into functions. Slay. ✨

👑 SEE ALSO 👑

Routines for manipulating stashes: Package::Stash; to work with lexicals: PadWalker.

🌸 AUTHORS 🌸

Andreas Koenig <andk@cpan.org> and Tom Christiansen <tchrist@perl.com>. Based on the old dumpvar.pl by Larry Wall. Legends, honestly. 🫶

This module is

Copyright (c) 1995, 1997, 2000, 2002, 2005, 2006 Andreas Koenig "<andk@cpan.org>".

All rights reserved.

This library is free software; you may use, redistribute and/or modify it under the same terms as Perl itself.

💌 That's the whole Devel::Symdump(3) page, bestie — this one came from perl v5.42.0 and is dated 2017-02-13. Go dump those symbols and remember: the symbol table is just a group chat you haven't been added to yet. 💅✨
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