not all paths return a value

[guy]

i have inherited the following migrated vb6 code (vb2005)
but i DONT get the "not all paths return a value" squiggly - is this a
'feature' of on error goto?

Private Function CreateFolder(By Val sFileName As String) As Boolean

On Error GoTo Errors

'Create it if necessary
If Directory.Exist s(sFileName) = False Then
Directory.Creat eDirectory(sFil eName)
End If

'Succeeded in creating a folder
CreateFolder = True

Errors:

End Function

[Patrice]

Looks like a normal behavior as all paths are likely returning a value as
all paths are ending with end function (and the implicit return value is
false). IMO you have rather this warning when you use the "exit function"
statement ??

--
Patrice

"guy" <gu*@discussion s.microsoft.com > a écrit dans le message de
news:5E******** *************** ***********@mic rosoft.com...

i have inherited the following migrated vb6 code (vb2005)
but i DONT get the "not all paths return a value" squiggly - is this a
'feature' of on error goto?

Private Function CreateFolder(By Val sFileName As String) As Boolean

On Error GoTo Errors

'Create it if necessary
If Directory.Exist s(sFileName) = False Then
Directory.Creat eDirectory(sFil eName)
End If

'Succeeded in creating a folder
CreateFolder = True

Errors:

End Function

[Patrice]

A value is still returned even if not explicit so Im' not sure the warning
would be fine here. Let's take the other way round. What kind of code would
create this warning ? (Exit Function ?)

--
Patrice

"Joergen Bech @ post1.tele.dk>" <jbech<NOSPAMNO SPAM> a écrit dans le message
de news:c1******** *************** *********@4ax.c om...

His point is that - on the surface - it does not *explicitly*
return a value.

/JB

On Tue, 3 Jan 2006 18:37:08 +0100, "m.posseth" <po*****@planet .nl>
wrote:

well it does return a value cause it returns false
as a boolean datatype can`t be nothing or empty

:-)

so what is the point ??

M. Posseth [MCP]
"guy" <gu*@discussion s.microsoft.com > schreef in bericht
news:7E******* *************** ************@mi crosoft.com...

this will definitely be rewritten, my point was the code as it stands does NOT warn about a code path that does not return a value

"John Timney ( MVP )" wrote:

I dont program in VB.NET - but not all paths return a value because
falling
into error before you set createFolder=Tr ue would fail to provide a
return
value, and you need to return a bool.

Put CreateFolder = False in your error section. Better still - start
using
try/catch statements and get rid of the goto
--
Regards

John Timney
Microsoft MVP

"guy" <gu*@discussion s.microsoft.com > wrote in message
news:5E******** *************** ***********@mic rosoft.com...
>i have inherited the following migrated vb6 code (vb2005)
> but i DONT get the "not all paths return a value" squiggly - is this a > 'feature' of on error goto?
>
> Private Function CreateFolder(By Val sFileName As String) As Boolean >
> On Error GoTo Errors
>
> 'Create it if necessary
> If Directory.Exist s(sFileName) = False Then
> Directory.Creat eDirectory(sFil eName)
> End If
>
> 'Succeeded in creating a folder
> CreateFolder = True
>
> Errors:
>
> End Function
>
>

[Ken Halter]

"guy" <gu*@discussion s.microsoft.com > wrote in message
news:5E******** *************** ***********@mic rosoft.com...

i have inherited the following migrated vb6 code (vb2005)
but i DONT get the "not all paths return a value" squiggly - is this a
'feature' of on error goto?

Errors:

End Function

I've read a few of these answers that state something along the lines of:

Just put a "CreateFold er = False" line after the "Errors:" label.

That should never be required. Since False is the default return value for
any boolean function/variable/whatever, explicitly setting the return =
False should never be required. If it is suddenly required after 30 years of
programming, there should be a huge notice posted on the web somewhere that
says "forget about your existing source code, everything has suddenly
changed for no good reason"

--
Ken Halter - MS-MVP-VB (visiting from VB6 world) - http://www.vbsight.com
Please keep all discussions in the groups..

[Herfried K. Wagner [MVP]]

"Joergen Bech @ post1.tele.dk>" <jbech<NOSPAMNO SPAM> schrieb:

To me it seems that they have forgotten to implement the check for 'On
Error
GoTo'...

As far as I understand it, the squiggly lines are not based on the
source text you see, but what the parser turns it into. Which in this
case is an entirely different beast. See my other post.

The occurance of the warning depends on the return type of the function. So
it's not actually a bug, but I believe the warning could have been
implemented in a way that it is also shown for functions which return a
value type.

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://classicvb.org/petition/>

[Herfried K. Wagner [MVP]]

"Patrice" <no****@nowhere .com> schrieb:

Looks like a normal behavior as all paths are likely returning a value as
all paths are ending with end function (and the implicit return value is
false). IMO you have rather this warning when you use the "exit function"
statement ??

Consider this sample:

\\\
Public Function Foo() As Object
If True Then
Return "x"
End If
End Function
///

This function implicitly returns 'Nothing' on all code paths too if no
return value is set. So I do not think that this is a big difference to the
scenario the OP described, although the warning is shown for the code above.

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://classicvb.org/petition/>

[Herfried K. Wagner [MVP]]

Ken,

"Ken Halter" <Ken_Halter@Use _Sparingly_Hotm ail.com> schrieb:

i have inherited the following migrated vb6 code (vb2005)
but i DONT get the "not all paths return a value" squiggly - is this a
'feature' of on error goto?

Errors:

End Function

I've read a few of these answers that state something along the lines of:

Just put a "CreateFold er = False" line after the "Errors:" label.

That should never be required. Since False is the default return value for
any boolean function/variable/whatever, explicitly setting the return =
False should never be required. If it is suddenly required after 30 years
of programming, there should be a huge notice posted on the web somewhere
that says "forget about your existing source code, everything has suddenly
changed for no good reason"

You could actually disable the warning. Simply open up the project file in
a text editor and add the warning number (42105) to the 'NoWarn' element.
My main concern is that the warning only occurs at functions which return a
reference type.

The full text of the warning makes this more clear: "[...] A null reference
exception could occur at run time when the result is used". I do not think
that implicitly returning 'Nothing' is a big problem. The main problem is
IMO forgetting to set a return value for a certain code path inside the
function. The same problem applies to BC42104 too. I have summed up my
thoughts on the usefulness of this warning in an article (in German):

Zur Sinnhaftigkeit der Compilerwarnung BC42104
<URL:http://dotnet.mvps.org/dotnet/articles/bc42104/>

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://classicvb.org/petition/>

[Patrice]

Sorry I don"t have 2005 hand. Even with a boolean return value ? What is the
code create for this ? I wonder what is the exact condition that triggres
this warning...

--
Patrice

"Herfried K. Wagner [MVP]" <hi************ ***@gmx.at> a écrit dans le
message de news:eP******** ******@TK2MSFTN GP14.phx.gbl...

"Patrice" <no****@nowhere .com> schrieb:

Looks like a normal behavior as all paths are likely returning a value as all paths are ending with end function (and the implicit return value is
false). IMO you have rather this warning when you use the "exit function" statement ??
Consider this sample:

\\\
Public Function Foo() As Object
If True Then
Return "x"
End If
End Function
///

This function implicitly returns 'Nothing' on all code paths too if no
return value is set. So I do not think that this is a big difference to

the scenario the OP described, although the warning is shown for the code above.
--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://classicvb.org/petition/>

[Herfried K. Wagner [MVP]]

"Patrice" <no****@nowhere .com> schrieb:

Sorry I don"t have 2005 hand. Even with a boolean return value ? What is
the
code create for this ? I wonder what is the exact condition that triggres
this warning...

The warning will only work if the function's return type is a reference
type.

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://classicvb.org/petition/>

[Patrice]

Thanks for the follow up...

--
Patrice

"Herfried K. Wagner [MVP]" <hi************ ***@gmx.at> a écrit dans le
message de news:e$******** *****@tk2msftng p13.phx.gbl...

"Patrice" <no****@nowhere .com> schrieb:

Sorry I don"t have 2005 hand. Even with a boolean return value ? What is
the
code create for this ? I wonder what is the exact condition that triggres this warning...

The warning will only work if the function's return type is a reference
type.

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://classicvb.org/petition/>

[Joergen Bech]

On Tue, 3 Jan 2006 19:21:52 +0100, "Herfried K. Wagner [MVP]"
<hi************ ***@gmx.at> wrote:

"Joergen Bech @ post1.tele.dk>" <jbech<NOSPAMNO SPAM> schrieb:

To me it seems that they have forgotten to implement the check for 'On
Error
GoTo'...

As far as I understand it, the squiggly lines are not based on the
source text you see, but what the parser turns it into. Which in this
case is an entirely different beast. See my other post.

The occurance of the warning depends on the return type of the function. So
it's not actually a bug, but I believe the warning could have been
implemented in a way that it is also shown for functions which return a
value type.

Care to give me an example that involves On Error Goto?

It is true that the squiggly lines appear for

Public Function ObjectDoesProdu ceSquiggleLines () As Object
'Do nothing
End Function

but not for

Public Function ValueProducesNo SquiggleLines() As Boolean
Dim b As Boolean = True
End Function

But when the "On Error ..." abomination is used, as in the sample
the original poster provided ...

Check the samples below. None of them produce squiggly lines, even
though I am fairly positive that they cover both objects and value
types as return values. I see no difference in behavior due to
the choice of return types.

If you look at what the compiler turns the samples into, you will
see that something is explicitly returned on all code paths in all
samples.

---snip---
Option Explicit On
Option Strict On
....
Public Function GetString() As String
On Error GoTo someerror
Return ""
SomeError:
End Function

Public Function GetObject() As Object
On Error GoTo SomeError
Return Nothing
SomeError:
End Function

Public Function GetBoolean() As Boolean
On Error GoTo SomeError
Return False
SomeError:
End Function

Public Function GetArrayList() As ArrayList
On Error GoTo SomeError
Return New ArrayList
SomeError:
End Function
---snip---

Regards,

Joergen Bech