[ANN] pervasives-0.0.1

[ara.t.howard]

NAME

pervasives.rb

SYNOPSIS

access to pristine object state. if you don't metaprogram you probably
don't need it

INSTALL

gem install pervasives

URIS

http://rubyforge.org/projects/codeforpeople/
http://codeforpeople.com/lib/ruby

SAMPLES

<========< samples/a.rb >========>

~ > cat samples/a.rb

#
# Pervasives allows objects' method to be accessed in a pristine state, even
# when some effort has been made to derride them
#
require 'pervasives'

class OpenStruct
instance_methods.each{|m| undef_method m unless m[%r/__/]}

def initialize
@table = {}
end

def method_missing m, *a, &b
case m.to_s
when %r/[=]$/
@table[m.to_s.delete('=')] = a.shift
when %r/[?!]$/
!!@table[m.to_s.delete('?!')]
else
@table[m.to_s]
end
end

def inspect
@table.inspect
end
end

os = OpenStruct.new

os.object_id = 42
os.send = 42
os.instance_eval = 42

p os

p os.object_id
p Pervasives.object_id(os)

p os.send
p Pervasives.send(os, "key=", "value")

p os.instance_eval
p Pervasives.instance_eval(os){ @table }

~ > ruby samples/a.rb

{"instance_eval"=>42, "send"=>42, "object_id"=>42}
42
-609487514
42
"value"
42
{"instance_eval"=>42, "send"=>42, "key"=>"value", "object_id"=>42}


<========< samples/b.rb >========>

~ > cat samples/b.rb

#
# sometimes it may be more convenient to use a Pervasives:roxy object
# insteand of using Pervasives directly
#
require 'pervasives'

class BlankSlate
instance_methods.each { |m| undef_method m unless m =~ /^__/ }

def object_id() 42 end
end

bs = BlankSlate.new

proxy = Pervasives:roxy.new bs

p bs.object_id
p proxy.object_id

~ > ruby samples/b.rb

42
-609489100


<========< samples/c.rb >========>

~ > cat samples/c.rb

#
# the special '__' method accesses an object's Pervasives:roxy
#
require 'pervasives'

class BlankSlate
instance_methods.each { |m| undef_method m unless m =~ /^__/ }
def object_id() 42 end
end

bs = BlankSlate.new

p bs.object_id
p __(bs){ object_id }

~ > ruby samples/c.rb

42
-609486982


<========< samples/d.rb >========>

~ > cat samples/d.rb

#
# it all works for classes too
#
require 'pervasives'

class C
def self.new() raise end
def inspect() 42 end
end

p( Pervasives.new(C) )
p( Pervasives:roxy.new(C).new )
p( __(C).new )

~ > ruby samples/d.rb

42
42
42



enjoy and send in yer comments/patches!

-a

 

[Trans]

NAME

pervasives.rb

SYNOPSIS

access to pristine object state. if you don't metaprogram you probably
don't need it [snip]
enjoy and send in yer comments/patches!

well, of course i think it's great that you took the time to do this.
but i'm afraid i have an unfortunate little story to tell you.

you see about a year ago i was working on my BasicObject implementation
and how to deal with this exact problem. if you recall i brought up
this very thing on ruby-talk. i had implemented my own version of
Pervasives -- i beleive it was call Meta and/or Inspect at first, but i
later realized the methods fit well in ObjectSpace. tied to this I
created a shortcut to these mthod via a proxy like yours but rather
than '__(obj).foo', mine was 'obj.__.foo.'. Hey, great mind think
alike!

now the tragic ending... with my new lib in hand i went about reworking
my meta code with it. well, it wasnt too long after that i realized it
sucked. my meta-code become bloated, harder to read and slower -- it
just wasn't worth it. and so i gave up on it.

so that' my little story and i fear the same will happen for you. i
think if the issue is going to be truly addressed, we need to work on
something more fundamental. btw eventually i just settled on using
object_class and object_send aliases when need be (shadow methods
__class__, __send__, etc. just got on my nerves) and lived with the
over-ride imperfections.

T.

 

[Trans]

enjoy and send in yer comments/patches!

_ = Pervasives

_.send(obj, message)

T.

 

[Gregory Brown]

_ = Pervasives

_.send(obj, message)

Ooh. I think that at least in the context of this lib, that's
reasonable enough.

Surely concise

 

[ara.t.howard]

_ = Pervasives

_.send(obj, message)

yeah - i thought about that, but i use '_' often in loops like

hash.map{|k,_| k.upcase}

when i plan to ignore a block param.

cheers.

-a

 

[Gregory Brown]

yeah - i thought about that, but i use '_' often in loops like

hash.map{|k,_| k.upcase}

when i plan to ignore a block param.

Hmm, also a good tip Ara, neat.

 

[Trans]

enjoy and send in yer comments/patches!

is this perhaps impossible b/c of callbacks? since any dot magic DSL is
created via method_missing how can we possibley remove all the methods
including #method_missing? and if we're stuck with one exception, what
does a half-dozen more really make (just so long as they have uncommon
names)?

t.