instant refresh

James Bott · Post by **James Bott** » Wed Aug 29, 2007 3:00 pm

Ehab,

>Could you please help in syntax.

I'm not sure what syntax you mean. Did you mean making a browseDelete() method? If so, you just define it in your class definition and name the method--just the same as the current delete() method you have. Actually, you can just rename it in both places.

Code: Select all

class ... from TData
   ...
   method BrowseDelete()
endclass

method BrowseDelete()
   ...
return self

OK, you may be cofused about the way the current delete method is defined. Because "delete" is a reserved word, we have to use a special way of defining it. This is only used for reserved words.

Code: Select all

class ... from TData
   message delete method _delete
endclass

method _delete()
...
return self

James

Ehab Samir Aziz · Post by **Ehab Samir Aziz** » Wed Aug 29, 2007 9:04 pm

Oka I did it in such a way but about calling the two methods ?

Code: Select all

//--- meter class
class Tmeter from TData
   method new
   method browser
   method add
   method edit
   message delete method BrowseDelete
 Hidden:
   data lAdd as logical
endclass

//--- meter class
class Tmeterdelete from TData
     method new
     method browser
     method add
     method edit
     method DBFdelete   
   Hidden:
     data lAdd as logical
endclass
  

..

method BrowseDelete(oBrw,oMeter) 
   ::skip(1)    
   ::skip(0)    
if oBrw:eof()
   ::skip(-1)    
   ::skip(0)    
endif
oBrw:refresh()    
   

return self

//---------------------------------------------------------------------------//

method DBFdelete(oMeter,oBrw) 
local nRecno

   if msgYesNo("Delete this record?")  
      super:delete() 
   endif 


nRECNO := oMeter:RECNO() 
   oMeter:pack()
GOTO nRECNO

return self

James Bott · Post by **James Bott** » Wed Aug 29, 2007 9:23 pm

Ehab,

No, it is much simpler.

Code: Select all

//--- meter class 
class Tmeter from TData 
   method new 
   method browser 
   method add 
   method edit 
   method BrowseDelete 
 Hidden: 
   data lAdd as logical 
endclass 

.. 

method BrowseDelete(oBrw,oMeter)
   if msgYesNo("Delete this record?")  
      ::delete() 
   endif  
   ::skip(1)    
   ::skip(0)    
   if oBrw:eof() 
      ::skip(-1)    
      ::skip(0)    
   endif 
   oBrw:refresh()    
return self

Keep in mind that this is a table class (we call them DBFs) so a browse function (method) doesn't really belong in this class, but we are doing it because it is easier than adding it to the TXBrowse class. You don't want to mess with the table delete method and it shouldn't have any interfaces in it--you may want to call it from other code (as we did above in the BrowseDelete() method).

Also you don't ever want to change the name of the method (like DBFDelete) because you want all tables to have a delete method (called "delete"). This is one of the basics of using OOP and it allows you to do things like pass any object and call the delete method. If each object had a different name for the delete method then you would have to code a large DO CASE statement and add to it for each new object--not good. You can't do this with procedural coding.

Code: Select all

function whatever( oObject )
    oObject:delete()
return self

Also you do not need a new class for a new method. The method is part of the existing class--in your case TMeter.

See OOP is really simple.

James

Ehab Samir Aziz · Post by **Ehab Samir Aziz** » Thu Aug 30, 2007 4:38 am

Where in code can I pack the deleted records and in same time keep the existing browse as BrowseDelete(oBrw,oMeter) ? I f packed the shape of the browse is going to be redisplayed aganist BrowseDelete(oBrw,oMeter).
Thanks

James Bott · Post by **James Bott** » Thu Aug 30, 2007 5:05 am

Ehab,

You cannot pack a data file while it is being used. It must be in exclusive use and it takes way too long. My suggestion as before is to reuse records. Or, you can pack during reindexing which also requires exclusive use.

When you delete records with SET DELETED ON, they will be invisible so there is no need to pack. Also when you when you index you should always use the FOR NOT DELETED() clause so the index record count will not include deleted records.

James

Ehab Samir Aziz · Post by **Ehab Samir Aziz** » Thu Aug 30, 2007 1:53 pm

Any way to delete and pack at the same time beside keeping the browse as BrowseDelete() do ?

James Bott · Post by **James Bott** » Thu Aug 30, 2007 1:58 pm

Ehab,

>Any way to delete and pack at the same time beside keeping the browse as BrowseDelete() do ?

Did you read my previous message? No, you cannot pack a file after deleting a record, nor would it be practical even if you could. This has nothing to do with the browse delete method--you can't do it using any method or function.

James

Ehab Samir Aziz · Post by **Ehab Samir Aziz** » Sat Sep 01, 2007 3:46 pm

No harm fom putting pack after using the file like below or you think there is a better place to for the pack for the deleted commands :

Code: Select all

 use mete exclusive
    index on me_mc_serl to mete
    index on me_date to mete2
    pack
    use

James Bott · Post by **James Bott** » Sun Sep 02, 2007 1:06 am

Ehab,

No you don't want to do it that way either. What if the database has a million records? Every time the user opens the file it is going to get packed which could take a half hour.

You have to pack databases using a separate routine that the user can call occassionally. You can leave deleted records in the database for quite some time unless you are deleting lots of them and if you doing that you need to rethink the design.

Still the best solution is to reuse deleted records. Then you never have to PACK.

James