World: r3wp

Anyway many thanks Steve for hints!

You can also use the /seek and /part refinements to pass arguments 
to your READ actor.

My convention is to simulate the behavior of a standard block (I 
called my schemle virtual-block).

So it's the main reason why I don't use read or write but copy/append 
instead

Seems the standard functions are overloaded somehow even when you 
writes your own, (because you want different functionality of course) 
aah deep lake, deep lake

Steeve your virtual block is more persisten block isnt it? ;)

true

there are lot of rooms for improvement in my code, perhaps some day...

OK I'll try to finish simple rif:// scheme and update rif.r in rebol.org 
thanks guys for hepl! Documentation should be improved in file schemes, 
there is almost nothink.

nothing sorry

Another curriosity when I defined actors put/get when used port returns 
error message "no put actor"

Anyway when defined /seek refinement the sheme start to work as expected

I don't think you can define your own actors ...

You're limited to the ones defined ...

When you use an actor like 'open, it checks to see if the actor is 
defined in the network scheme and invokes that.

The functions Steeve mimick for his virtual block scheme are not 
originaly actors but works for him

Let me rephrase that .. you can't define an actor if that word is 
already in use

What? that is exactly what Steeve does if I understand

which actor is that?

the funtions defined in actor object aren't actually actors?

;** MISSING !!! native FOREACH has not port! as parameter

so they can't be used actors

You can use them as local functions .. just not as actors

the allowed actors are the function with port! as parameter

action!s, to be precise

and if they don't take a port, you can't use them without redefining 
their behaviour

ok i'll try to understand :-(
my scheme works used port: open rif:// ... read/seek port 1

but don't work the easy way: read rif://data/file 1, cant access 
locales

locales?

you can easily make `read/seek rif://data/file 1` work, by creating 
a custom open? actor and using that in your read actor

I use locales to stor opened files (I need two files )

Andreas any simple example of open? ?

Assuming you store port-local state in port/state, you can simply 
check port/state for not being none.

isn't it the right way? :
actor: [
		open: func [port [port!] /local path ] [
            parse port/spec/ref [thru #":" 0 2 #"/" path:]
            append port/spec compose [path: (to-file path)]
            port/locals: []
            either (0 = length? port/locals) [

                append port/locals open/seek rejoin [port/spec/path ".dat"]

                append port/locals open/seek rejoin [port/spec/path ".idx"]
                ][

                port/locals/1 open/seek rejoin [port/spec/path ".dat"]

                port/locals/2 open/seek rejoin [port/spec/path ".idx"]
            ]
        return port

you'll most likley want `port/locals: copy []`

but based on that, your open? actor would simply be: `open?: func 
[port [port!]] [not none? port/locals]`

OK I'll try it

0 = length? port/locals

can be

empty? port/locals

and in your read actor, you'll then simply do:

either open? port [{read was invoked as `open rif:// + read`}] [{read 
was invoked directly as read rif://}]

>> read/seek rif://data/file 1
** Script error: cannot access locals in path port/locals/2
** Where: Get-RIF read
** Near: Get-RIF port number

OK andreas

Maybe also a simple `if not open? port [open port]` will suffice 
in your case.

(Within the read actor.)

But typically you'll also want to add code to close the port again, 
afterwards.

can't you paste the whole code somewhere ?

This automatic open close is not clear to me after Andreas there 
is no such automation? where is the magic? :-O

There is no magic.

Rebol [
    file: %prot-rif.r
    title: "RIF protocol"
    author: "Pavel"
    rights: 'PD
    date: 13-Aug-2010
    ]

;; Local functions

Append-RIF: func [port [port!] record [binary!] ][


 write/append port/locals/2 to-binary length? head port/locals/1		;index 
 port the end of data file will be beginning of new record

 write/append port/locals/1 record							        ;data port new record 
 into data file


 return shift length? head port/locals/2 -3					        ;number of 
 records 8 bytes per record
]


Get-RIF: func [ port [port!] i [integer!] /local numentry indexpos 
recpos recend value ][


    numentry: shift length? head port/locals/2 -3                    
       ;number of records 8 bytes per record


 if any [i = 0 i > numentry] [return none]                        
    ;numbering starts at 1 ends at file end


 indexpos: multiply subtract i 1 8					                ;compute index 
 offset
	recpos: to-integer read/seek/part port/locals/2 indexpos 8

  either ( (8 * i) = length? head port/locals/2 ) [				;last record 
  special case
		recend: length? head port/locals/1
		][

  recend: to-integer read/seek/part port/locals/2 add indexpos 8 8		;internal 
  record
		]

 return read/seek/part port/locals/1 recpos subtract recend recpos
]

;; Scheme definition
make-scheme [
	name: 'rif
	title: "RIF Protocol"
	spec: make system/standard/port-spec-head []
    awake: none

	actor: [
		open: func [port [port!] /local path ] [
            parse port/spec/ref [thru #":" 0 2 #"/" path:]
            append port/spec compose [path: (to-file path)]
            port/locals: copy []
            either (0 = length? port/locals) [

                append port/locals open/seek rejoin [port/spec/path ".dat"]

                append port/locals open/seek rejoin [port/spec/path ".idx"]
                ][

                port/locals/1 open/seek rejoin [port/spec/path ".dat"]

                port/locals/2 open/seek rejoin [port/spec/path ".idx"]
            ]
        return port
        ]

        close: func [port [port!]] [
            foreach  port port/locals [close port]
        ]

        read: func [port [port!] /seek number [integer!] ] [
            Get-RIF port number
        ]

        write: func [port [port!] record [binary!]] [
            Append-RIF port record
        ]

    ]
]

arghh... not here ;-)

There are action!s in R3, which operate in port!s.

If you define custom schemes, you can implement how those actions 
behave for ports using your scheme by writing what we call "actors".

This is the elementary principle to understand.