NAME¶
Mason::Manual::UpgradingFromMason1 - Summary of differences between Mason 1 and
Mason 2
DESCRIPTION¶
Mason 2.x comes ten years after Mason 1.0 (known as HTML::Mason) and twelve
years after the original Mason release. It has been rearchitected and
reimplemented from the ground up.
That said, the philosophy and core syntax are similar enough that it should
still be recognizable and "feel like Mason" to existing users.
This manual attempts to summarize the differences between Mason 1 and 2, to help
existing users decide if they are interested and, if so, migrate their
projects.
There is currently no automated way to convert a Mason 1 to a Mason 2 site, but
there hopefully will be someday. (Contributions welcome. :))
ARCHITECTURE¶
- •
- In Mason 1, each component was an instance of a common
Component class. In Mason 2, each component is its own Moose class,
with a class name generated from the component path.
- •
- The main component body - the content and the inline Perl
sections - are placed into a "main" method.
- •
- Calling a component (via "<& &>" or
"$m->comp" ) entails creating a new instance of the component
class, and calling its "main" method. Component call parameters
are passed to the constructor and placed in attributes.
MAJOR FEATURES¶
- •
- Plugins now utilize Moose roles and are much more
powerful and flexible than in Mason 1. Some features that were (or would
have been) in the core of Mason 1 are now in plugins. See
Mason::Manual::Plugins.
- •
- Web integration in Mason 1 was centered around
mod_perl and was part of the core. In Mason 2 all web integration has been
split out into a companion web framework, Poet, which in turn uses PSGI to
integrate with any server backend. You can also use Mason as the
templating layer in popular web frameworks such as Catalyst and Dancer.
There is no longer anything web-specific in the Mason core.
- •
- Subcomponents have been eliminated, replaced with
class methods.
- •
- Error processing/formatting has been eliminated.
Mason now simply throws fatal errors to the caller. In a Plack
environment, Plack::Middleware::StackTrace will catch the error and format
it nicely.
- •
- Resolvers and Anonymous components have been
eliminated. Components need to be in files. If your components live in
another data source, you could use FUSE
<http://fuse.sourceforge.net/> or a custom plugin to keep a file
hierarchy up to date with the data source.
- •
- Caching support has been simplified.
"$m->cache" simply returns a CHI object with an appropriate
namespace for the component.
SYNTAX¶
- •
- "<%once>" has been replaced with
"<%class>".
- •
- "<%cleanup>" has been eliminated; it was
not very useful anyway, since it was not guaranteed to run after an
exception. You can use add_cleanup to add cleanup code for the end of the
request, which is good enough in most cases, or you can add a
"DEMOLISH" method to the component.
- •
- Single blank lines between blocks are now removed, so you
can space blocks out for readability without generating a ton of
newlines.
- •
- Whitespace is required after a %-line and around the
expression in a "<% %>" tag. This improves readability and
leaves open the possibility of additional syntax.
- •
- "<%args>" and "<%shared>"
are gone. Use Moose attributes instead.
- •
- "<%method>" and "<%def>"
have been replaced with just "<%method>", which creates a
true class method rather than a subcomponent.
- •
- The "<%filter>" tag is now used to define
filters, instead of automatically applying a filter to the current
component.
- •
- "Components with content" syntax has been
eliminated; use the CompCall filter instead.
- •
- "Escape flags" in substitution tags now utilize
filters.
MISC PARAMETER CHANGES¶
Interp parameters¶
- •
- "buffer_preallocate_size",
"code_cache_max_size" and "use_object_files" have been
deemed unnecessary and eliminated.
- •
- "escape_flags" has been eliminated; define
filters instead.
- •
- "data_dir" now defaults to a directory created
with tempdir.
- •
- "preloads" has been eliminated; this code does
roughly the same:
$interp->load($_) for (grep { /some_condition/ } $interp->all_paths);
Request parameters¶
- •
- "autoflush" and "max_recurse" have been
eliminated because they are too difficult to implement efficiently.
Compiler parameters¶
- •
- "preprocess", "postprocess_perl", and
"postprocess_text" have been eliminated; similar effects can be
achieved with plugins targeting Mason::Compilation.
- •
- "default_escape_flags" has been eliminated, but
see Mason::Plugin::DefaultFilter for a third-party substitute.
MISC METHOD CHANGES¶
Interp methods¶
- •
- "exec" has been renamed to run.
Request methods¶
- •
- "cache_self" has been eliminated; use the Cache
filter instead.
- •
- "callers", "caller" and
"caller_args" have been eliminated; now that component calls are
simply method calls underneath, they are too difficult to implement
efficiently.
- •
- "call_next" has been replaced with Moose's
"inner".
- •
- "call_self" has been eliminated; use filters
instead.
- •
- "current_comp" has been eliminated. Within a
component, use $self; outside a component you can call current_comp_class,
which will at least get you the class.
- •
- "dhandler_arg" has been renamed to
path_info.
- •
- "exec" has been renamed to run.
- •
- "fetch_comp" has been renamed to load.
- •
- "subexec" has been replaced with visit and
go.
SEE ALSO¶
Mason
AUTHOR¶
Jonathan Swartz <swartz@pobox.com>
COPYRIGHT AND LICENSE¶
This software is copyright (c) 2011 by Jonathan Swartz.
This is free software; you can redistribute it and/or modify it under the same
terms as the Perl 5 programming language system itself.