Accessor methods and property syntax in .NET

Davy_B · September 7, 2010, 10:37am

Hi all,

IronRuby has a nice trick where attributes defined by attr_reader,
attr_accessor and attr_writer are usable as properties from C#… i was
just
wondering: is it possible to use the same trick in our own ruby code?

or can anyone just point me in the right direction as to where in the
IronRuby source code i could find where this is being done?

I have accessor methods that really need to do something specific and
ideally, i’d like them be usable as properties in .NET since it leads to
a
much nicer syntax in C#

brs,
Davy

Davy_B · September 7, 2010, 11:06am

You can just define them as attr_accessors and then implement the
methods

class Foo

attr_accessor :bar, :baz

def bar=(val)
# do more stuff here for example
@bar = val
end

def bar
@bar
end

end

Davy_B · September 7, 2010, 11:14am

if i do that, calling bar as a property like this:

var value = myObject.bar;

leads to ‘value’ being an instance of IronRuby.BuiltIns.RubyMethod, and
not
the value that is in the @bar instance field

which

i’m using 1.1 btw, not sure how this would behave on 1.0

from looking at the IronRuby source code, it looks like i need to find a
way
to change the RubyMemberInfo for a given accessor method to
RubyAttributeReaderInfo or RubyAttributeWriterInfo

Davy_B · September 7, 2010, 11:56am

your solution does however work for the assignment accessor… in fact,
you
can do something like this:

class Foo
attr_reader :bar

def bar=(val)
# do more stuff here for example
@bar = val
end

end

and then you can do the following in C#:

var value = myObject.bar;
myObject.bar = someOtherValue;

for my specific scenario, i think i can actually get by with just
overriding
the assignment accessor but the thing i’m wondering is: is the current
behavior actually a bug? and will this behavior be preserved in future
releases?

Davy_B · September 7, 2010, 2:47pm

Actually, we discussed this about a month ago:
http://rubyforge.org/pipermail/ironruby-core/2010-July/007154.html

http://rubyforge.org/pipermail/ironruby-core/2010-July/007154.htmlThe
outcome was that a feature request was added to allow for C# properties
to
be defined using getter/setter in ruby. I was going to look at
implementing
it… got into a bit, and had a baby… Haven’t looked at it since.

B

Davy_B · September 7, 2010, 2:57pm

Hey Brian,

i saw that thread, but didn’t really see a definitive answer as to how
to
work around it until it’s implemented (though i might’ve missed it),
which
is why i thought i’d raise the question again

Davy_B · September 7, 2010, 2:57pm

Beware!
Contributing to the IronRuby source code might result in having
babies!!!

Congratulations Brian!

Davy_B · September 9, 2010, 11:05am

I love how he just tossed that off like it happens to everybody.

“Yeah, I know, I was committing this source patch, but all of a sudden
there
was this crying squalling thing in my lap that needed a diaper changed.
WTF
is up with that? . I know! Seriously! I thought good code wasn’t
supposed to
have side effects?!? I kept looking to ROLLBACK, but sonuvagun, wouldn’t
you
know it…”

Congrats, Brian.

Ted Neward

Java, .NET, XML Services

Consulting, Teaching, Speaking, Writing

http://www.tedneward.com

From: [email protected]
[mailto:[email protected]] On Behalf Of Shay F.
Sent: Tuesday, September 07, 2010 5:57 AM
To: [email protected]
Subject: Re: [Ironruby-core] accessor methods and property syntax in
.NET

Beware!

Contributing to the IronRuby source code might result in having
babies!!!

Congratulations Brian!

On Tue, Sep 7, 2010 at 3:47 PM, Brian G. [email protected]
wrote:

Actually, we discussed this about a month ago:
http://rubyforge.org/pipermail/ironruby-core/2010-July/007154.html

The outcome was that a feature request was added to allow for C#
properties
to be defined using getter/setter in ruby. I was going to look at
implementing it… got into a bit, and had a baby… Haven’t looked at
it
since.

B

On Tue, Sep 7, 2010 at 5:55 AM, Davy B. [email protected] wrote:

your solution does however work for the assignment accessor… in fact,
you
can do something like this:

class Foo
attr_reader :bar

def bar=(val)

# do more stuff here for example

@bar = val

end

and then you can do the following in C#:

var value = myObject.bar;
myObject.bar = someOtherValue;

for my specific scenario, i think i can actually get by with just
overriding
the assignment accessor but the thing i’m wondering is: is the current
behavior actually a bug? and will this behavior be preserved in future
releases?

On Tue, Sep 7, 2010 at 11:13 AM, Davy B. [email protected]
wrote:

if i do that, calling bar as a property like this:

var value = myObject.bar;

leads to ‘value’ being an instance of IronRuby.BuiltIns.RubyMethod, and
not
the value that is in the @bar instance field

which

i’m using 1.1 btw, not sure how this would behave on 1.0

from looking at the IronRuby source code, it looks like i need to find a
way
to change the RubyMemberInfo for a given accessor method to
RubyAttributeReaderInfo or RubyAttributeWriterInfo

On Tue, Sep 7, 2010 at 11:01 AM, Ivan Porto Carerro
[email protected]
wrote:

You can just define them as attr_accessors and then implement the
methods

class Foo

attr_accessor :bar, :baz

def bar=(val)

# do more stuff here for example

@bar = val

end

def bar

@bar

end

On Tue, Sep 7, 2010 at 10:36 AM, Davy B. [email protected]
wrote:

Hi all,

IronRuby has a nice trick where attributes defined by attr_reader,
attr_accessor and attr_writer are usable as properties from C#… i was
just
wondering: is it possible to use the same trick in our own ruby code?

or can anyone just point me in the right direction as to where in the
IronRuby source code i could find where this is being done?

I have accessor methods that really need to do something specific and
ideally, i’d like them be usable as properties in .NET since it leads to
a
much nicer syntax in C#

brs,
Davy

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