name = nil unless defined?(name)
phone = nil unless defined?(phone)

In fact, I often use this to define default value for the locals that are passed in, while letting an explicitly passed-in value of nil mean that the default value should be used, such as:

name = ‘unknown’ unless (defined?(name) && name)

That was all using RHTML…recently I started converting an existing rhtml-based project to haml and ran into a specific problem with this technique…but only when using a boolean value for a local. Consider that I want passing the local specifically to true or false to be preserved, but if you don’t specify it or pass in nil, then it should use a default value of true. So…I did this:

show_name = true unless (defined?(show_name) && !show_name.nil?)

This works like a charm when the partial is rhtml, but with haml, it seems that if I explicitly pass false for show_name to the partial, that it gets converted to nil. Doh!

Not sure what path I am going to choose to address this in a large existing code base that relies on it…I might have to try out the _haml_local_assigns tactic mentioned above.

For a simple code example that reproduces this problem, see my writeup on it at: http://sleeplesscoding.blogspot.com/2008/11/bug-in-haml-partial-rendering.html

I totally agree that partials are analogous to methods. I am starting to learn to refactor reused peices of views into partials.

options ||= {}

This approach of course makes setting the optional locals a little clumsier when invoking the partial. I like though that it makes it more clear when you are referencing an optional param in your partial. For clarity and to keep them separate from local variables, I would have prefered if Rails would have set all params passed to a partial in a hash called say partial.

It’s strange that there’s not an easy DRY solution for this in rails. I originally used your implementation, but then decided it was way too much writing for my taste (my fingers get tired/sore easily).

I hacked up my own little plugin that does something similar (here: http://geekninja.blogspot.com/2007/09/rails-plugin-optional-parameters-for.html ).

Simple, but works alright in my opinion.

title = local_assigns[:title]
Isn’t it?

Or just use local_assigns[:title] instead title – as it’ wont raise any errors