Module::Lazy - postpone loading a module until it's actually used
use Module::Lazy "My::Module";
# My::Module has not been loaded
my $var = My::Module->new;
# My::Module is loaded now, and new() method is called
# Force loading of all postponed modules
In large projects loading all the dependencies may take a lot of time. This module attempts to reduce the startup time by postponing initialization. The improvement be significant for unit test scripts and small command-line tools which do not utilize all the functionality at once.
This comes at a cost of reduced stability, as load-time errors are also postponed. The no Module::Lazy directive is provided to mitigate the risk by forcing the pending modules to load.
When use Module::Lazy "Some::Module"; is called, the module in question is not loaded. A stub package with the same name is created instead.
use Module::Lazy "Some::Module";
Should any method call be performed on the stub package, it loads the original one and jumps to respective method.
In particular, can() and isa() are overloaded and will trigger module loading.
Upon loading, import is not called on the target package. This MAY change in the future.
No extra options (except from target module name) are allowed.
Calling no Module::Lazy; or, alternatively, Module::Lazy->unimport; will cause all postponed modules to be loaded immediately, in alphabetical order.
This may be useful to avoid deferred errors and/or side effects of module loading.
No extra options to unimport are supported.
If PERL_LAZYLOAD_DEBUG is set and true, warns about module loading via Carp.
If PERL_LAZYLOAD_DISABLE is set and true, don't try to lazyload anything - just go straight to require.
(That's roughly equivalent to perl -M-Module::Lazy on command line).
The following symbols are currently replaced by stubs in the module to be loaded: AUTOLOAD, DESTROY, can, isa.
If a module was ever lazyloaded, a normal require would do nothing. A method must be called to inflate the module.
This is done so because a normal require would partially overwrite stub methods and potentially wreak havoc.
A fake $VERSION = 10**9 is generated so that use Module x.yy doesn't die. This value is erased before actually loading the module.
use Module x.yy
use mro 'c3'; does not work with lazy-loaded parent classes.
use mro 'c3';
import() is not called on the modules being loaded. The decision is yet to be made whether it's good or bad.
no way to preload prototyped exported functions (that's what autouse does), but maybe there should be?
certainly not enough interoperability tests.
Please report bugs via github or RT:
bug-module-lazy at rt.cpan.org
You can find documentation for this module with the perldoc command.
You can also look for information at:
RT: CPAN's request tracker (report bugs here)
AnnoCPAN: Annotated CPAN documentation
autouse is another module with similar idea, however, it does it for imported functions rather than methods.
Copyright 2019 Konstantin S. Uvarin, <firstname.lastname@example.org>
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To install Module::Lazy, copy and paste the appropriate command in to your terminal.
perl -MCPAN -e shell
For more information on module installation, please visit the detailed CPAN module installation guide.