Using and Dispose

[sam]

Hi,
If I use "Using" do I sill need to call Dispose Method?
ex
Using F as Font=new Font(...)
.....
end Using
is that enough to free F
or, do I need to call F.dispose()
TIA
Sam

 

[Tom Shelton]

Hi,
If I use "Using" do I sill need to call Dispose Method?
ex
Using F as Font=new Font(...)
....
end Using
is that enough to free F
or, do I need to call F.dispose()
TIA
Sam

Using will call dispose for you - that is the whole reason for it It is
basically syntactical sugar for:

Dim o As SomeDisposableObject
Try
o = New DisposableObject()
o.DoCoolStuff()
Finally
If o IsNot Nothing Then
o.Dispose()
End If
End Try

 

[Mythran]

Using will call dispose for you - that is the whole reason for it It
is
basically syntactical sugar for:

Dim o As SomeDisposableObject
Try
o = New DisposableObject()
o.DoCoolStuff()
Finally
If o IsNot Nothing Then
o.Dispose()
End If
End Try

I see it more like Sweet n Low instead of pure sugar


Mythran

 

[Harry Strybos]

Hi,
If I use "Using" do I sill need to call Dispose Method?
ex
Using F as Font=new Font(...)
....
end Using
is that enough to free F
or, do I need to call F.dispose()
TIA
Sam

Pardon me if this is a bit patronising.

Following the advice provided by Tom (an excellent fellow), it is useful to
call many objects using the "Using" keyword. A further example is to call a
modal form this way e.g

Using frm As New frmMyForm()
frm.ShowDialog(Me)
End Using

or

Using frm As New frmMyForm()
With frm
.ShowDialog(Me)
If .DataChanged Then 'a user property of the form
Call RefreshRoutine 'some method to refresh data
End If
End With
End Using

I believe the "Using" statement guarantees disposal even if an error has
occurred

 

[Brian Gideon]

Hi,
If I use "Using" do I sill need to call Dispose Method?
ex
   Using F as Font=new Font(...)
....
   end Using
is that enough to free F
or, do I need to call F.dispose()
TIA
Sam

Like Tom said 'Using' does that for you. And by the way, 'Using' is
not the only construct that does that. The For Each loop will
automatically call Dispose on the IEnumerator if it happens to implent
IDisposable as well.

 

[Tom Shelton]

Like Tom said 'Using' does that for you. And by the way, 'Using' is
not the only construct that does that. The For Each loop will
automatically call Dispose on the IEnumerator if it happens to implent
IDisposable as well.

Thank goodness it does! What a pain that would be if it didn't - you would
have to write your for eaches that used disposable enumerators like:

Dim e As IEnumerator = o.GetEnumerator()
for each item as otype in e
...
next
e.dispose()

 

[Brian Gideon]

Thank goodness it does!  What a pain that would be if it didn't - you would
have to write your for eaches that used disposable enumerators like:

Dim e As IEnumerator = o.GetEnumerator()
for each item as otype in e
        ...
next
e.dispose()

Yeah, that would suck