Dynamically accessing values of variables

[veevers]

Progress is a pretty new language to me. I'm used to many other languages and am having trouble finding how to use progress for dynamic needs.

I am trying to access a variable's value when getting the name of the variable dynamically.

for example: i have a variable named 'firstname'.

i have a list of the fields the user wants to see (and a list of the corresponding variable names).

is there anyway i can have one function that takes the variable name as a string and returns me the value that the variable is holding?

i know i can call a procedure that way, for example:
def var varname as char initial "procname".
run value(varname).

i hope i was clear as to what i need to do. i need a simple solution.

thanks!

 

[jongpau]

I don't think you can access Progress variables in the way you would like to...

However, you say you have a "list of fields the user wants to see"; does that mean database fields? If so (and if you are on Progress version 9 or higher) you can use dynamic queries and buffers to access fields and their values dynamically.

 

[veevers]

paul,

thanks for responding.
i didn't think that there was any way to do it. i wish there was.
do you have an example of the syntax for a dynamic query that i can refer to, to see if it will suit my needs?
can it query from more than one table?
thanks!

 

[vinod_home]

Hi,

You should be abled to do it using include files. You can always do it by generating dynamic program code from within the source program code.

Hope that helps,

 

[jongpau]

Let me see (dry typing here without having Progress open at the moment):

DEF VAR lhQuery AS HANDLE NO-UNDO.
 DEF VAR lhBuffer AS HANDLE NO-UNDO.
 
 CREATE QUERY lhQuery.
 CREATE BUFFER lhBuffer FOR TABLE "<TableName>":U.
 lhQuery:ADD-BUFFER(lhBuffer).
 lhQuery:QUERY-PREPARE("FOR EACH <TableName> NO-LOCK WHERE.....(your where clause goes here)":U).
 lhQuery:QUERY-OPEN.
 lhQuery:GET-FIRST.
 
 DO WHILE NOT lhQuery:QUERY-OFF-END:
   MESSAGE lhBuffer:BUFFER-FIELD("<FieldName>":U):BUFFER-VALUE VIEW-AS ALERT-BOX.
   lhQuery:GET-NEXT.
 END. /* do while not query-off-end */
 
 lhQuery:QUERY-CLOSE.
 DELETE OBJECT lhQuery.
 DELETE OBJECT lhBuffer.

In the above "<TableName>" is the name of the database table and can be replaced with a variable. Same goes for the actual query string in the QUERY-PREPARE and the field name(s) used in BUFFER-FIELD.

HTH

 

[rlambert]

Hi


when you say variables do you mean database fields or local/global variables?

 

[rlambert]

hows this

Using 2 levels of indirection this may work for you if the variables are variables and not data fields

first an include file

/*------------------------------------------------------------------------
File : classVar.i
Purpose :
Author(s) : R Lambert
Created : DEC 2004

description : defines a class type variable whose underlying variable should not be directly
accessed. Use get<varName>() or set<varName>(<value>) to assign and retrieve
the data.


Useage :
{classvar.i
&varName = xyz - name of variable
&dataType = charcater|integer|logical|... data type of var
&extent = 5 - extent of variable or do not define it if no extent
&mode = PRIVATE or not defined

}
example
classVar.i defines a character var called Name

setName("fred").

display getName().

----------------------------------------------------------------------*/


&IF DEFINED(EXTENT) <> 0 &THEN
&SCOPED-DEFINE defVarExtent EXTENT {&EXTENT}
&SCOPED-DEFINE localExtent {&EXTENT}
&else
&SCOPED-DEFINE defVarExtent
&endif
&IF DEFINED(mode) <> 0 &THEN
&IF "{&MODE}" <> "PRIVATE" &THEN
&MESSAGE INVALID MODE {&mode} - classvar.i
&UNDEFINE mode
&ENDIF
&ENDIF
&IF DEFINED(varName) = 0 &THEN
&MESSAGE VARIABLE NAME NOT DEFINED - classvar.i
&ENDIF
&IF DEFINED(dataType) = 0 &THEN
&MESSAGE DATA TYPE NOT DEFINED
&ENDIF
DEF VAR _m{&varName} AS {&dataType} {&defVarExtent} NO-UNDO.
FUNCTION set{&FnName} RETURNS LOGICAL {&mode}
(&if DEFINED(localExtent) <> 0 &then INPUT entryNo AS INTEGER , &endif
INPUT ip_m AS {&dataType}) .
&IF DEFINED(localExtent) <> 0 &THEN
IF entryNo > {&localExtent} OR entryNo < 1 THEN RETURN ERROR.
ASSIGN
_m{&varName}[entryNo] = ip_m NO-ERROR.
&ELSE
ASSIGN
_m{&varName} = ip_m NO-ERROR.
&ENDIF
RETURN ERROR-STATUS:ERROR.
END FUNCTION.
FUNCTION get{&FnName} RETURNS {&dataType} {&mode}
&if DEFINED(localExtent) <> 0 &then (INPUT entryNo AS INTEGER ) &endif .
RETURN &if DEFINED(localExtent) <> 0 &then _m{&varName}[entryNo] &else _m{&varName} &endif .
END FUNCTION.

/ *********end of include ***************************** */

suggested way of using it

/**************************************************/


{demoClassVar.i &varName=FirstName &dataType=CHARACTER}
{demoClassVar.i &varName=LastName &dataType=CHARACTER}
FUNCTION getA RETURNS CHARACTER
(cVarName AS CHARACTER):
RETURN DYNAMIC-FUNCTION("get" + cVarName).

END FUNCTION.
FUNCTION setA RETURNS CHARACTER
(cVarName AS CHARACTER
,cValue AS CHARACTER):
DYNAMIC-FUNCTION("set" + cVarName,cValue).

END FUNCTION.
setA("firstName","fred").
setA("lastName","bloggs").

MESSAGE
getA("firstName")
SKIP
getA("lastName")
SKIP
VIEW-AS ALERT-BOX INFO BUTTONS OK.


/**************************************************/


hope this helps