How to get dynamically the type of a variable

[Nicolas D]

hi,
In Ctd there is SalGetDataType( Window_Handle ) to get the type of a Window Handle.
How to get the type of a variable ?
thanks

[Jeff Luther]

You mean during running of the application??? There is no SAL function to do this, and I have never seen this question before because you do not have access to a list of vars. to figure out, so...

My first answer is: Using a var. naming convention should/will let you know the var. type, but again you don't have access to the names of the vars. during runtime, so I'm not sure I understand your question. In any event, the naming I mean is like:

Boolean: bFoo
DateTime: dt
Number: n
Long String: ls
String: s
Window Handle: hWnd
Custom Control: cc
Funct. Class: oSomeClassType

and so on. Practically every sample of code I have seen uses this convention so there is plenty around to learn from. Otherwise, what do you have in mind??

[Christian Schubert]

Hi Nicolas,

you can use SalCompileAndEvaluate to accomplish this. Just use the name of the variable as the expression (first param). The return value will be the type of the variable. Have a look at the help file...

HTH

Christian Schubert

[Dave Rabelink]

hi,
In Ctd there is SalGetDataType( Window_Handle ) to get the type of a Window Handle.
How to get the type of a variable ?
thanks

I use SalCompileAndEvaluate.

This function returns the type of the variable when used as the expression parameter.

Code: Select all

Set nType = SalCompileAndEvaluate( sExpression, nError, nErrorPos, nReturn, sReturn, dtReturn, hWndReturn, FALSE, sContext )
   If nType = EVAL_Number
            ! Variable is a Number
   Else If nType = EVAL_String
            ! Variable is a String
   Else if ntype = EVAL_Date
            ! Variable is a DateTime
   Else If nType = EVAL_Handle
            ! Variable is a Handle


So for instance you want to determine the type of the variable nUserID :

Code: Select all

Set nType = SalCompileAndEvaluate( "nUserID", nError, nErrorPos, nReturn, sReturn, dtReturn, hWndReturn, FALSE, sContext )


Dave

PS Oh, Christian has posted just before me

[Jeff Luther]

Well, there you go. Learn something new every day! Thanks you 2 for the hint!

P.S. Dave, I see this, though:
Else If nType = EVAL_Handle
! Variable is a Handle

meaning you can't tell if it's a File, Session, Sql, Window Handle, right?

[Christian Schubert]

meaning you can't tell if it's a File, Session, Sql, Window Handle, right?

Hi Jeff,

no, you can't tell. All three types are the same. For example "SalWindowHandleToNumber" also converts file and sql handles...

Christian

[Dave Rabelink]

I was just curious to see if SalCompileAndEvaluate could determine an object.

Code: Select all

Set nType = SalCompileAndEvaluate( "udvTest", nError, nErrorPos, nReturn, sReturn, dtReturn, hWndReturn, FALSE, sContext )


In fact, the function returns here nType = 7 !

This is the list of EVAL constants as described in the manual

Code: Select all

EVAL_Number   = 1
EVAL_String   = 2
EVAL_Date     = 3
EVAL_Handle   = 4
EVAL_Template = 5
EVAL_Set      = 99
EVAL_If       = 100


So what is nType = 7 ?

Another addition.

Code: Select all

Set nType = SalCompileAndEvaluate( "cfcTest", nError, nErrorPos, nReturn, sReturn, dtReturn, hWndReturn, FALSE, sContext )


Will return EVAL_Template (5). In this case cfcTest is a class.

[Nicolas D]

So ...
Thanks a lot to everybody !!!