special Codeblock Syntax under Fivewin

[Jimmy]

hi,

i saw in some Code Syntax like this

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 <||
    local oRect := oDlg:  GetCliRect  (  )
       oBar:  nWidth := oRect:  nWidth
       oLbx:  nWidth := oRect:  nWidth -   210
    RETURN   NIL
 >

where can i read "more" about this Syntax

in above Sample you need to pass oLbx as Parameter but how using that Syntax

---

here a Sample how i pass Parameter to Codeblock

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#include "FiveWin.ch"
PROCEDURE MAIN
LOCAL a := 1
LOCAL b := "a"
LOCAL cBlock, bBlock
   // you can per-build Codeblock as String
   cBlock := "{|a,b| DoTest(a,b)}"

   bBlock := &(cBlock)
   Eval(bBlock,a,b)

return

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FUNCTION DoTest(a,b)
? a, VALTYPE(a)
? b, VALTYPE(b)
RETURN 0
 

as you can see i include Parameter between "|" (Pipe) Sign of Codeblock and pass them at EVAL()

[hmpaquito]

Hi Mr. Jimmy,

They are named extended codeblocks
https://vivaclipper.wordpress.com/tag/codeblock/


This (extra) syntax too is correct for harbour:

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{|| 
      a:= 1
      b:= 2
      c:= 3 
 }

Regards

[hua]

This is xHarbour style of extended codeblock

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<|oLbx|
    local oRect := oDlg:  GetCliRect  (  )
       oBar:  nWidth := oRect:  nWidth
       oLbx:  nWidth := oRect:  nWidth -   210
    RETURN   NIL
 >
 

Harbour style

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{|oLbx|
    local oRect := oDlg:  GetCliRect  (  )
       oBar:  nWidth := oRect:  nWidth
       oLbx:  nWidth := oRect:  nWidth -   210
    RETURN   NIL
 }
 

Just remember that extended codeblock must have RETURN

http://harbouradvisor.blogspot.com/2011 ... locks.html

[hmpaquito]

Hi Hua,

Just remember that extended codeblock must have RETURN

It's not required return clause. Return clause it's neccessary only for return value

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// Not neccessary return value. Only code. Implicity return value is NIL
x:= {||
         a:= 1
         b:= 2
         c:= 3 
      }

// Return value
y:= {||
         a:= 1
         b:= 2
         c:= 3 
         return b 
      }

Regards

[Jimmy]

hi,

thx all for Answer

It's not required return clause. Return clause it's neccessary only for return value

ah, that was what have confuse me

[cnavarro]

Dear Jimmy
This syntax for codeblock, RETURN is required

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   local bBlock
   bBlock  := <|| 
                  local a := 1
                  local b := 2
                  local c := 3
                  Return nil
               >

 

[hmpaquito]

Estimado Cristóbal,

La siguiente, sin return, es una sintaxis válida, que dará NIL como resultado de la operación Eval( bBlock )

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 local bBlock
   bBlock  := <||
                  local a := 1
                  local b := 2
                  local c := 3
               >
 

Atte.

[cnavarro]

Estimadísimo Paquito
Yo es que soy un poco perfeccionista y como al no tener RETURN me da el siguiente mensaje ( tengo los warnings activados ) y como sabemos un codeblock es tratado internamente como si fuese una FUNCTION Anonymous

D:\FWH\FWHTEAM\SAMPLES\testtoast.prg(17) Warning W0007 Function '{||...}' does not end with RETURN statement
Compilation Errors
Link Error

[hmpaquito]

Hola Cristóbal,

Pues sí. Debe ser como tu dices: Los warning mandan y definen la sintaxis correcta.

Así en "stricto sensu" hay que poner un return en los extended codeblocks

Gracias por la aclaración

[nageswaragunupudi]

It's not required return clause. Return clause it's neccessary only for return value

"Return" is not required with xHarbour.
"Return" is required with Harbour.

So it is always safe to use return <someval> or return nil.
Our program should with both with Harbour and xHarbour.

It is always a good idea to keep our programs compatible with both Harbour and xHarbour and this is a must for us the FWteam.
It is safe to use this template:

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< |params,..|
  // code
  return any
>
 

xHarbour:
Angular brackets is the right syntax for xHarbour and the return statement does not hurt xHarbour

Harbour:
Fivewin.ch translates the angular brackets ( < .. > ) to curly braces ( {..} ) when using Harbour and we also comply with the requirement of return statement.

Adantage of the extended codeblock syntax is that, we can use local variables and use commands like a normal program.

[hmpaquito]

Thank you very much Mr. Rao for your extense y comprensive explication