[Jprogramming] Passing class member gerund to verb in another locale

Fri Sep 1 14:51:38 UTC 2017

this one has the "near hope" of working

myVerb2=: 3 : 0 
funcB_B_ (mean__this ` '') 
)
except that what gets passed is a "late bound" name, and "this" does not exist in B

  mean__newA ` '' 
┌──────────┐ 
│mean__newA│ 
└──────────┘

Raul provided a locative.  My versions,

loc_z_ =: (,&'_'@[ ,&'_'@, ":@>@])"1 0 boxopen 

locs_z_ =: 1 : 'm loc 18!:5 ''''' 

 'mean' locs 
mean_base_ 

'mean' loc newA 
mean_0_
 'mean' locs_A_ 
mean_A_

so rewrite,

myVerb2 =: 3 : 0
funcB_B_ < 'mean' locs
)

You don't need a "this" assignment in create.________________________________
From: 'Jon Hough' via Programming <programming at jsoftware.com>
To: programming at jsoftware.com 
Sent: Friday, September 1, 2017 9:59 AM
Subject: Re: [Jprogramming] Passing class member gerund to verb in another locale

I see. I apologize, my pseudo-python examples were misleading. I am calling funcB from a method of newA. Not form outside the class definition. The python pseudo-code is wrong in this regard.

coclass 'A'

create=: ....

this=: coname '' 

)

myVerb1=: 3 : 0

funcB_B_ (mean ` '')

)

myVerb2=: 3 : 0

funcB_B_ (mean__this ` '')

)

myVerb3=: 3 : 0

funcB_B_ (mean f.  ` '') NB. as you already stated this loses locale info.

)

myVerb1,myVerb2,myVerb3 would all fail.

As I stated previously, I think my best bet is just to pass a myA reference into funcB and be done with it. I think I am trying to twist the locale system into doing something it is not designed for. 

--------------------------------------------

On Fri, 9/1/17, 'Pascal Jasmin' via Programming <programming at jsoftware.com> wrote:

Subject: Re: [Jprogramming] Passing class member gerund to verb in another locale

To: "programming at jsoftware.com" <programming at jsoftware.com>

Date: Friday, September 1, 2017, 10:44 PM

You only need to do 

newA =: conew 'A'

funcB mean__newA`'' ; 0 

2

that will use whatever "copy of d" that

is set in newA

________________________________

From: 'Jon Hough' via Programming

<programming at jsoftware.com>

To: programming at jsoftware.com

Sent: Friday, September 1, 2017 9:41

AM

Subject: Re: [Jprogramming] Passing

class member gerund to verb in another locale

You are correct. However, I really need

to use an instance of A (actually the possibility of several

instances existing at the same time).

If I am absolutely sure I only have one

instance of A, i.e. myA, then I could cache the reference in

the A locale

cocurrent 'A'

instance=: '' NB. none by default

coclass 'A'

create=: 3 : 0

... do stuff...

instance_A_=: coname ''

)

Then once I have the reference, as I

understand it, I can do pretty much anything by switching in

and out of locales, and grab myA's reference when in B. This

will only work if there is a single instance of A.

But, my whole purpose is to have

several different instances of A, any of whose member verbs

can be passed (as gerunds or however else) to some verb in B

locale. 

It seems that  an object's verbs

do not contain any reference to the actual object, so what I

want is pretty difficult to do in J.

Although this is trivial in some other

languages, e.g. pseudo-python:

# create two instances of A

myA =A(1)

myOtherA = A(10000)

# pass the instances' method1 to some

utility function, "interestingFunction"

# and get some interesting results.

result1 =

interestingFunction(myA.method1)

result2 = 

interestingFunction(myOtherA.method1)

It seems J's locale system does not

handle this very well. 

--------------------------------------------

On Fri, 9/1/17, 'Pascal Jasmin' via

Programming <programming at jsoftware.com>

wrote:

Subject: Re: [Jprogramming] Passing

class member gerund to verb in another locale

To: "programming at jsoftware.com"

<programming at jsoftware.com>

Date: Friday, September 1, 2017, 10:19

PM

this simplification seems to

work, (defined in base)

d_A_ =: 1 2 3 

mean_A_ =: 3 :

'(+/ % #) d' 

mean_A_ 0 

2 

NB. use F8, also works with funcB_B_

definition

funcB=: 3 : 0

'vrb data' =: y

f=: vrb `:6 

f data 

) 

funcB mean_A_`'' ; 0

2

geoMean_A_ =: 3 : 0 

NB. same as before, but add d. 

d+(#%:(*/)) y 

)

funcB geoMean_A_`'' ; 2 3 4 

3.8845 4.8845 5.8845

funcB_B_ geoMean_A_`'' ; 2 3 4 

3.8845 4.8845 5.8845

the create verb only gets

called when you do conew, and so d is

not defined for

non-instanced locale.  one way to

fix this is to have a

default value for d that will get

overwritten with the

create verb so that it both works with

the "raw"

locale and instances.

________________________________

From: 'Jon Hough' via Programming

<programming at jsoftware.com>

To: programming at jsoftware.com

Sent: Friday, September 1, 2017 8:48

AM

Subject: Re: [Jprogramming] Passing

class

member gerund to verb in another

locale

Hi Pascal.

Thanks for the response. You are

correct in this case. Not

to move the goal posts, but 

funcB_B_ geomean_A_`'' ;

will not work

if geoMean is redefined to be

geoMean_A_ =: 3 : 0

NB. same as before, but add

d.

d+(#%:(*/)) y

)

The variable

d was created in myA's create verb.

This is not visible

from _A_ locale.

I will repost the entire (modified)

source

below. Note that getAvg__myA calls

funB_B_ with gerund

geoMean__myA. 

coclass

'A'

create=: 3 : 0

d=:y

)

geoMean=: 3 : 0

d+(#%:(*/)) y

)

myVerb=: 3 : 0

((geoMean )  ; (+/%#)) y

)

getAvg=: 3 : 0

data=.y

funcB_B_ (myVerb_A_ `''); data

)

cocurrent

'B'

NB. accepts the object ref as param.

NB. helper verb, for special

case of

NB. classes with a

member verb called myVerb.

funcB2=: 3 : 0

'obj data'=: y

verb=. 3 : ' myVerb__obj

y'

funcB ((verb f.)

`'');data

)

NB. More general verb, accepts any

verb

NB. (assuming verb is callable

from this locale)

funcB=: 3

: 0

'vrb data' =:

y

f=: vrb `:6

f data

)

myA=: 1 conew 'A'

geoMean__myA 1 2 3   NB. no

problem here

   getAvg__myA 1 2 3   NB.

error here

--------------------------------------------

On Fri, 9/1/17, 'Pascal

Jasmin' via Programming <programming at jsoftware.com>

wrote:

Subject: Re: [Jprogramming] Passing

class

member gerund to verb in another

locale

To: "programming at jsoftware.com"

<programming at jsoftware.com>

Date: Friday, September 1,

2017, 8:19 PM

funcB_B_ geomean_A_`'' ;

data

do not use f. inside funcB.  f.

will

lose locale info

From: 'Jon Hough' via

Programming <programming at jsoftware.com>

  To: programming at jsoftware.com

  Sent:

Friday, September 1, 2017 1:09 AM

  Subject: Re: [Jprogramming]

Passing class

member gerund to verb in

another locale

I forgot to

add a definition of funcB 

cocurrent 'B'

funcB=: 3 :

0

'vrb data' =:

y

f=: vrb

`: 6  NB. vrb is the

gerund

f data  NB.

call f. This creates the

error.

)

--------------------------------------------

On Fri, 9/1/17, 'Jon

Hough' via

Programming

<programming at jsoftware.com>

wrote:

  Subject:

[Jprogramming] Passing class

member gerund to verb in

another locale

  To: "Programming

Forum" <programming at jsoftware.com>

  Date: Friday, September 1,

2017, 2:03 PM

  My problem is,  I have

a

class 'A' say.

  and I have a locale

'B'.

  A contains

several verbs. I would like

  to pass a verb

(or gerunds of the verbs), let's call

it

  myVerb, to some verb in B.

However, this

creates a

problem,

  as

  when

the B verb tries to call myVerb it

  cannot

find it, being in a different locale.

i.e. I

get a

  value error. I

attempted to use fix (f.) to

get myVerb

explicitly, but this only

  works if myVerb does not contain

any

  other verbs from A.

  This is the contrived example,

that is

  essentially the same as my

real problem, but

stripped

of

  superfluous

things:

  NB. A is some class with

several

  verbs.

coclass

'A'

create=: 3 : 0

  d=:y 

  )

  NB.

some

verb in A

  geoMean=: 3 : 0

  (#%:(*/)) y

  )

  NB. I want

to pass this to another

verb

  in another

locale.

  NB. Note that it calls geoMean.

  myVerb =: 3 : 0

  ((geoMean

f.)  ; (+/%#)) y

  )

  NB. calling a verb in B

  getAvg=: 3 : 0

  data=.y

  funcB_B_ ( myVerb f. `''); data

  )

  NB.

create my instance of A

  myA =: 0 conew

'A'

  NB. call myVerb. No

problem

here!

  myVerb__myA 1 2 3

NB. pass

myVerb to funcB_B_

getAvg__myA 1 2

3

  NB. this gives an error

|value error:

geoMean

  |   ((geoMean 

f.);(+/%#))y

Solutions:

(1) One solution is to make

funcB_B_ a

conjunction / adverb. But in

reality, I want to send several

  verbs to

funcB together. 

  (2) Another solution is

to

send the

  instance reference of A to

funcB

(i.e. just send the

whole

  of myA to

funcB).

But I would prefer

not to send the whole

object, as it then makes B less

flexible,

because I may

want

  to call funcB_B_ without

the need for

a class

instance, just

  a

standalone

verb.

  (3) Another solution is to

not call

any

  other verbs of myA inside

myVerb__myA.

This is not

a

  realistic solution as

A could

be quite

complicated.

  Is there a better way?

  Just to

explain my motivation, I am

  trying to replicate the

functionality

most

languages that

  have first-class

functions

possess - to pass

arbitrary

  function(s)

to

  other functions and call them.

  e.g. in  Python

  # myVerb is a Python function,

and

  could be a member method of

some class.

someData is

just

  some data

def funcB

(myVerb, someData):

  return

myVerb(someData,

  someOtherData)

Obviously J doesn't have

first class

functions in this sense, but

with gerunds, I was hoping to

  be able to

recreate the functionality.

----------------------------------------------------------------------

  For information about J

forums see http://www.jsoftware.com/forums.htm

----------------------------------------------------------------------

For information about J forums

see http://www.jsoftware.com/forums.htm

----------------------------------------------------------------------

For information about J forums

see http://www.jsoftware.com/forums.htm

----------------------------------------------------------------------

For information about J forums

see http://www.jsoftware.com/forums.htm

----------------------------------------------------------------------

For information about J forums see http://www.jsoftware.com/forums.htm

----------------------------------------------------------------------

For information about J forums see http://www.jsoftware.com/forums.htm

----------------------------------------------------------------------

For information about J forums see http://www.jsoftware.com/forums.htm

----------------------------------------------------------------------

For information about J forums see http://www.jsoftware.com/forums.htm