class question

[Don Dickinson]

I am just getting started with classes in pbwin9 and was wondering what I'm doing wrong. I'm working on building a stringlist class. Internally the list is stored as an array. The example below crashes (win vista) with a "the program is not responding" message immediately when run. I tried putting message boxes in the constructor and the crashing functions, but get the same crash. It seems whenever the object is referenced, it crashes. Hopefully I'm just doing something easy and stupid.

Tia,
Don

'
'  c_stringlist.bas
'
#compile exe
#dim all

class CStringList
   instance m_count as long
   instance m_strings() as string

   '--------------------------------------------------------------------------
   '- constructor
   class method CREATE()
      dim m_strings(0 to 0) as instance string
      m_count = 0
   end method

   '--------------------------------------------------------------------------
   '- destructor
   class method DESTROY()
      erase m_strings()
   end method

   '--------------------------------------------------------------------------
   interface I_STRING_LIST
      inherit CUSTOM

      '-----------------------------------------------------------------------
      method add(stringValue as string)

         incr m_count
         redim preserve m_strings(0 to m_count) as instance string
         m_strings(m_count) = stringValue

      end method

      '-----------------------------------------------------------------------
      method count() as long
         method = m_count
      end method

      '-----------------------------------------------------------------------
      method countAsString() as string
         method = trim$(str$(m_count))
      end method

      '-----------------------------------------------------------------------
      property get value ( byval iWhich as long ) as string

         if (iWhich > ubound(m_strings)) and (iWhich <= ubound(m_strings)) then
            property = m_strings(iWhich)
         else
            property = ""
         end if

      end property

      '-----------------------------------------------------------------------
      property set value ( byval iWhich as long, byval sValue as string )

         if (iWhich > ubound(m_strings)) and (iWhich <= ubound(m_strings)) then
            m_strings(iWhich) = sValue
         end if

      end property

   end interface

end class


function pbmain()

   dim lstString as I_STRING_LIST
   let lstString = class "TStringList"

   '- unremming this will cause a crash
   ''lstString.add "Test"

   '- unremming this will cause a crash
   'msgbox "List contains: " + lstString.countAsString + $cr + "1=" + lstString.value(1)

   '- this causes a crash
   msgbox "Ok: " +  lstString.countAsString

end function

[Fred Harris]

Just took a quick look Don, but I noticed a string parameter in Method Add(string) without a Byval override. I believe you need the Byval.

[Fred Harris]

I'll tell you what really improves the functioning though, and that is replacing this line...

let lstString = class "TStringList"

with this one

let lstString = class "CStringList"

[Don Dickinson]

haha, thanks fred. that was stupid. i was trying to resolve a problem with instance'd arrays (also my bug) and in doing so i renamed the class. guess i didn't rename it everywhere

thanks a bunch
don

[Michael Mattias]

[replace]
let lstString = class "TStringList"

with this one

let lstString = class "CStringList"

Or with

let lstString = class  $MY_CLASS_NAME

Using inline literals = Asking for trouble

[Dominic Mitchell]

let lstString = class $MY_CLASS_NAME

In this case you are asking for trouble. That is not allowed.
See the Help File entry for the LET statement.

[Charles Dietz]

Also in PROPERTY GET value() ...

IF (iWhich > LBOUND(m_strings)) ...

[Michael Mattias]

> [string equate] is not allowed [in LET statement]...

LET objvar = CLASS ClassName$

The term ClassName must be specified as a quoted string literal, which is the name of a class ....

String literal links to the page titled "Constants and Literals."

I tried both the "string literals" and "string constants" links from there, but neither says you can use a string contant in place of it.

Strange, I thought I remember reading in some part of help file that string equates may be used anywhere a string literal or string variable may be used.

If that's not true, tell me with a straight face it's not totally silly that a program would accept a quoted string literal but not a string equate.

MCM