PARTYP

Syntax PARTYP (name)
Location Toolkit II, THOR XVI

As disclosed in the description of DEFine FuNction, a parameter is passed to a SuperBASIC PROCedure or FuNction by reference, meaning that the variable type listed in the definition line will actually be overriden by the type of variable which has been passed as a parameter.

The function PARTYP returns the type of the actual parameter which has been passed, which can be used to error trap PROCedures and FuNctions. PARTYP expects only one parameter - the name of the parameter from the definition line to be looked at. PARTYP will then return one of the following values depending on the type of the actual parameter passed:

PARTYP Meaning
0 A null string has been passed.
1 A string has been passed.
2 A floating point has been passed.
3 An integer has been passed.

Example

A PROCedure to swap any two variables (it can only handle simple strings and variables, not arrays):

100 a=1:b%=2
110 swap_var a,b%
115 :
120 DEFine PROCedure swap_var (x,y)
130   LOCal xa,xa$,param
140   IF PARUSE(x)=0 OR PARUSE(y)=0
150     PRINT 'A variable is unset!':RETurn
160   END IF
162   IF PARNAM$(1)="" OR PARNAM$(2)=""
164     PRINT 'Parameters are not both variables!':RETurn
165   END IF
170   IF PARUSE(x)=3 OR PARUSE(y)=3
180     PRINT 'Arrays not handled':RETurn
190   END IF
200   param=PARTYP(x)
210   IF PARTYP(y)=1 AND param<>1 OR param=1 AND PARTYP(y)<>1
220     PRINT 'You cannot swap a string with a value!'
230     RETurn
240   END IF
250   SELect ON param
260     =0,1:xa$=y:y=x:x=xa$
270     =2,3:xa=y:y=x:x=xa
280   END SELect
290 END DEFine

NOTE 1

There is a difference in the way that PARTYP will report an omitted parameter, depending on whether you implicitly omit the parameter. Try the following using the above example:

Implicit omission:

swap_var a$

or even:

swap_var a$,

PARTYP(y) returns the type of the notional parameter (here y is a floating point, so PARTYP (y) returns 2), and PARUSE(y) also reports 2. Compare explicit omission:

swap_var ,a$

PARTYP(x) will return 0 as will PARUSE(x) If a program is Qliberated, PARTYP will return 0 whether parameters are implicitly or explicitly omitted.

NOTE 2

If you pass a null string as a parameter, eg:

swap_var a$,''

in the above example, PARTYP will still return 1 (and not zero) as you may think, hence the need to look at PARUSE also.

NOTE 3

TURBO and SuperCHARGE cannot compile programs which use PARUSE.

CROSS-REFERENCE

PARTYP should be used alongside PARUSE to find out whether a parameter was passed as a variable (ie. by reference) or as a value. PARTYPE is the same. PARNAM$, PARHASH, PARSEPA and PARSTR$ form companions to these commands.