J
Jason Kendall
Why doesn't the new "IsNot" operator work in conjunction with
'Typeof'?
'Typeof'?
J
Jay B. Harlow [MVP - Outlook]
Jason,
IMHO:
Because IsNot is the inverse of the Is operator. They are both used to
compare object references.
http://msdn2.microsoft.com/en-us/library/kb136x1y(en-US,VS.80).aspx
http://msdn2.microsoft.com/en-us/library/t3bat82c(en-US,VS.80).aspx
The "Is" in the TypeOf operator is a placeholder & not the operator per se.
The TypeOf operator is used to check the data type of an object reference.
http://msdn2.microsoft.com/en-us/library/0ec5kw18(en-US,VS.80).aspx
--
Jay [MVP - Outlook]
..NET Application Architect, Enthusiast, & Evangelist
T.S. Bradley - http://www.tsbradley.net
| Why doesn't the new "IsNot" operator work in conjunction with
| 'Typeof'?
|
IMHO:
Because IsNot is the inverse of the Is operator. They are both used to
compare object references.
http://msdn2.microsoft.com/en-us/library/kb136x1y(en-US,VS.80).aspx
http://msdn2.microsoft.com/en-us/library/t3bat82c(en-US,VS.80).aspx
The "Is" in the TypeOf operator is a placeholder & not the operator per se.
The TypeOf operator is used to check the data type of an object reference.
http://msdn2.microsoft.com/en-us/library/0ec5kw18(en-US,VS.80).aspx
--
Jay [MVP - Outlook]
..NET Application Architect, Enthusiast, & Evangelist
T.S. Bradley - http://www.tsbradley.net
| Why doesn't the new "IsNot" operator work in conjunction with
| 'Typeof'?
|
J
Jason Kendall
"The "Is" in the TypeOf operator is a placeholder"
How very strange. That clears up why 'TypeOf' doesn't use
parenthesis.
Thanks.
How very strange. That clears up why 'TypeOf' doesn't use
parenthesis.
Thanks.
L
Larry Lard
Jay said:
So the 'Is' in 'TypeOf X Is T' 'IsNot' the 'Is' in 'X Is Y' ?
J
Jay B. Harlow [MVP - Outlook]
Larry,
| So the 'Is' in 'TypeOf X Is T' 'IsNot' the 'Is' in 'X Is Y' ?
By jove I think he's got it. ;-)
--
Jay [MVP - Outlook]
..NET Application Architect, Enthusiast, & Evangelist
T.S. Bradley - http://www.tsbradley.net
|
| Jay B. Harlow [MVP - Outlook] wrote:
| > Jason,
| > IMHO:
| >
| > Because IsNot is the inverse of the Is operator. They are both used to
| > compare object references.
| >
| > http://msdn2.microsoft.com/en-us/library/kb136x1y(en-US,VS.80).aspx
| > http://msdn2.microsoft.com/en-us/library/t3bat82c(en-US,VS.80).aspx
| >
| > The "Is" in the TypeOf operator is a placeholder & not the operator per
se.
|
| So the 'Is' in 'TypeOf X Is T' 'IsNot' the 'Is' in 'X Is Y' ?
|
| --
| Larry Lard
| Replies to group please
|
| So the 'Is' in 'TypeOf X Is T' 'IsNot' the 'Is' in 'X Is Y' ?
By jove I think he's got it. ;-)
--
Jay [MVP - Outlook]
..NET Application Architect, Enthusiast, & Evangelist
T.S. Bradley - http://www.tsbradley.net
|
| Jay B. Harlow [MVP - Outlook] wrote:
| > Jason,
| > IMHO:
| >
| > Because IsNot is the inverse of the Is operator. They are both used to
| > compare object references.
| >
| > http://msdn2.microsoft.com/en-us/library/kb136x1y(en-US,VS.80).aspx
| > http://msdn2.microsoft.com/en-us/library/t3bat82c(en-US,VS.80).aspx
| >
| > The "Is" in the TypeOf operator is a placeholder & not the operator per
se.
|
| So the 'Is' in 'TypeOf X Is T' 'IsNot' the 'Is' in 'X Is Y' ?
|
| --
| Larry Lard
| Replies to group please
|
J
Jay B. Harlow [MVP - Outlook]
Jason,
| How very strange. That clears up why 'TypeOf' doesn't use
| parenthesis.
Yea its strange, I think parenthesis would "complicate" the TypeOf syntax
unnecessarily as:
If TypeOf(anObject) Is Something Then
Is miss-leading, it too close to GetType. TypeOf "IsNot" GetType!
If TypeOf anObject Is Something Then
is different then:
If GetType(anObject) Is Something Then
Remember GetType(anObject) returns a specific type & checks to see if o is
specifically Something, where as TypeOf allows derived types & interfaces to
also match. For example:
Class Something
...
End Class
Class SomethingSpecific
Inherits Something
...
End Class
Dim anObject As Object
' anObject = New Something
' anObject = New SomethingSpecific
If TypeOf anObject Is Something Then
' both Something & SomethingSpecific match
End If
If GetType(anObject) Is Something Then
' only Something matches
End If
I suppose they could have implemented TypeOf as a function similar to CType
& DirectCast:
If TypeOf(anObject, Something) Then
IMHO However that doesn't read as well.
--
Jay [MVP - Outlook]
..NET Application Architect, Enthusiast, & Evangelist
T.S. Bradley - http://www.tsbradley.net
| "The "Is" in the TypeOf operator is a placeholder"
|
| How very strange. That clears up why 'TypeOf' doesn't use
| parenthesis.
|
| Thanks.
|
| --
| Jason Kendall
| (e-mail address removed)
|
|
|
| On Fri, 21 Oct 2005 10:33:08 -0500, "Jay B. Harlow [MVP - Outlook]"
|
| >Jason,
| >IMHO:
| >
| >Because IsNot is the inverse of the Is operator. They are both used to
| >compare object references.
| >
| >http://msdn2.microsoft.com/en-us/library/kb136x1y(en-US,VS.80).aspx
| >http://msdn2.microsoft.com/en-us/library/t3bat82c(en-US,VS.80).aspx
| >
| >The "Is" in the TypeOf operator is a placeholder & not the operator per
se.
| >The TypeOf operator is used to check the data type of an object
reference.
| >
| >http://msdn2.microsoft.com/en-us/library/0ec5kw18(en-US,VS.80).aspx
| How very strange. That clears up why 'TypeOf' doesn't use
| parenthesis.
Yea its strange, I think parenthesis would "complicate" the TypeOf syntax
unnecessarily as:
If TypeOf(anObject) Is Something Then
Is miss-leading, it too close to GetType. TypeOf "IsNot" GetType!
If TypeOf anObject Is Something Then
is different then:
If GetType(anObject) Is Something Then
Remember GetType(anObject) returns a specific type & checks to see if o is
specifically Something, where as TypeOf allows derived types & interfaces to
also match. For example:
Class Something
...
End Class
Class SomethingSpecific
Inherits Something
...
End Class
Dim anObject As Object
' anObject = New Something
' anObject = New SomethingSpecific
If TypeOf anObject Is Something Then
' both Something & SomethingSpecific match
End If
If GetType(anObject) Is Something Then
' only Something matches
End If
I suppose they could have implemented TypeOf as a function similar to CType
& DirectCast:
If TypeOf(anObject, Something) Then
IMHO However that doesn't read as well.
--
Jay [MVP - Outlook]
..NET Application Architect, Enthusiast, & Evangelist
T.S. Bradley - http://www.tsbradley.net
| "The "Is" in the TypeOf operator is a placeholder"
|
| How very strange. That clears up why 'TypeOf' doesn't use
| parenthesis.
|
| Thanks.
|
| --
| Jason Kendall
| (e-mail address removed)
|
|
|
| On Fri, 21 Oct 2005 10:33:08 -0500, "Jay B. Harlow [MVP - Outlook]"
|
| >Jason,
| >IMHO:
| >
| >Because IsNot is the inverse of the Is operator. They are both used to
| >compare object references.
| >
| >http://msdn2.microsoft.com/en-us/library/kb136x1y(en-US,VS.80).aspx
| >http://msdn2.microsoft.com/en-us/library/t3bat82c(en-US,VS.80).aspx
| >
| >The "Is" in the TypeOf operator is a placeholder & not the operator per
se.
| >The TypeOf operator is used to check the data type of an object
reference.
| >
| >http://msdn2.microsoft.com/en-us/library/0ec5kw18(en-US,VS.80).aspx
G
Guest
Larry,
I guess it really does depend on what the meaning of the word is is!
By the way, another place that Is is used strangely in the BASIC-style
languages is its use in the Case clause of a Select Case statement, when
using relational operators. For example:
Case Is > 12
I hate the fact that Is shows up there.
Kerry Moorman
I guess it really does depend on what the meaning of the word is is!
By the way, another place that Is is used strangely in the BASIC-style
languages is its use in the Case clause of a Select Case statement, when
using relational operators. For example:
Case Is > 12
I hate the fact that Is shows up there.
Kerry Moorman
J
Jay B. Harlow [MVP - Outlook]
Doh!
| If TypeOf(anObject, Something) Then
|
| IMHO However that doesn't read as well.
They could have used IsTypeOf
If IsTypeOf(anObject, Something) Then
Although it reads better then the above, I still prefer the TypeOf operator
as is...
--
Jay [MVP - Outlook]
..NET Application Architect, Enthusiast, & Evangelist
T.S. Bradley - http://www.tsbradley.net
message | Jason,
|| How very strange. That clears up why 'TypeOf' doesn't use
|| parenthesis.
| Yea its strange, I think parenthesis would "complicate" the TypeOf syntax
| unnecessarily as:
|
| If TypeOf(anObject) Is Something Then
|
| Is miss-leading, it too close to GetType. TypeOf "IsNot" GetType!
|
| If TypeOf anObject Is Something Then
|
| is different then:
|
| If GetType(anObject) Is Something Then
|
| Remember GetType(anObject) returns a specific type & checks to see if o is
| specifically Something, where as TypeOf allows derived types & interfaces
to
| also match. For example:
|
| Class Something
| ...
| End Class
|
| Class SomethingSpecific
| Inherits Something
| ...
| End Class
|
| Dim anObject As Object
| ' anObject = New Something
| ' anObject = New SomethingSpecific
|
| If TypeOf anObject Is Something Then
| ' both Something & SomethingSpecific match
| End If
|
| If GetType(anObject) Is Something Then
| ' only Something matches
| End If
|
| I suppose they could have implemented TypeOf as a function similar to
CType
| & DirectCast:
|
| If TypeOf(anObject, Something) Then
|
| IMHO However that doesn't read as well.
|
| --
| Jay [MVP - Outlook]
| .NET Application Architect, Enthusiast, & Evangelist
| T.S. Bradley - http://www.tsbradley.net
|
|
| || "The "Is" in the TypeOf operator is a placeholder"
||
|| How very strange. That clears up why 'TypeOf' doesn't use
|| parenthesis.
||
|| Thanks.
||
|| --
|| Jason Kendall
|| (e-mail address removed)
||
||
||
|| On Fri, 21 Oct 2005 10:33:08 -0500, "Jay B. Harlow [MVP - Outlook]"
||
|| >Jason,
|| >IMHO:
|| >
|| >Because IsNot is the inverse of the Is operator. They are both used to
|| >compare object references.
|| >
|| >http://msdn2.microsoft.com/en-us/library/kb136x1y(en-US,VS.80).aspx
|| >http://msdn2.microsoft.com/en-us/library/t3bat82c(en-US,VS.80).aspx
|| >
|| >The "Is" in the TypeOf operator is a placeholder & not the operator per
| se.
|| >The TypeOf operator is used to check the data type of an object
| reference.
|| >
|| >http://msdn2.microsoft.com/en-us/library/0ec5kw18(en-US,VS.80).aspx
|
|
| If TypeOf(anObject, Something) Then
|
| IMHO However that doesn't read as well.
They could have used IsTypeOf
If IsTypeOf(anObject, Something) Then
Although it reads better then the above, I still prefer the TypeOf operator
as is...
--
Jay [MVP - Outlook]
..NET Application Architect, Enthusiast, & Evangelist
T.S. Bradley - http://www.tsbradley.net
message | Jason,
|| How very strange. That clears up why 'TypeOf' doesn't use
|| parenthesis.
| Yea its strange, I think parenthesis would "complicate" the TypeOf syntax
| unnecessarily as:
|
| If TypeOf(anObject) Is Something Then
|
| Is miss-leading, it too close to GetType. TypeOf "IsNot" GetType!
|
| If TypeOf anObject Is Something Then
|
| is different then:
|
| If GetType(anObject) Is Something Then
|
| Remember GetType(anObject) returns a specific type & checks to see if o is
| specifically Something, where as TypeOf allows derived types & interfaces
to
| also match. For example:
|
| Class Something
| ...
| End Class
|
| Class SomethingSpecific
| Inherits Something
| ...
| End Class
|
| Dim anObject As Object
| ' anObject = New Something
| ' anObject = New SomethingSpecific
|
| If TypeOf anObject Is Something Then
| ' both Something & SomethingSpecific match
| End If
|
| If GetType(anObject) Is Something Then
| ' only Something matches
| End If
|
| I suppose they could have implemented TypeOf as a function similar to
CType
| & DirectCast:
|
| If TypeOf(anObject, Something) Then
|
| IMHO However that doesn't read as well.
|
| --
| Jay [MVP - Outlook]
| .NET Application Architect, Enthusiast, & Evangelist
| T.S. Bradley - http://www.tsbradley.net
|
|
| || "The "Is" in the TypeOf operator is a placeholder"
||
|| How very strange. That clears up why 'TypeOf' doesn't use
|| parenthesis.
||
|| Thanks.
||
|| --
|| Jason Kendall
|| (e-mail address removed)
||
||
||
|| On Fri, 21 Oct 2005 10:33:08 -0500, "Jay B. Harlow [MVP - Outlook]"
||
|| >Jason,
|| >IMHO:
|| >
|| >Because IsNot is the inverse of the Is operator. They are both used to
|| >compare object references.
|| >
|| >http://msdn2.microsoft.com/en-us/library/kb136x1y(en-US,VS.80).aspx
|| >http://msdn2.microsoft.com/en-us/library/t3bat82c(en-US,VS.80).aspx
|| >
|| >The "Is" in the TypeOf operator is a placeholder & not the operator per
| se.
|| >The TypeOf operator is used to check the data type of an object
| reference.
|| >
|| >http://msdn2.microsoft.com/en-us/library/0ec5kw18(en-US,VS.80).aspx
|
|
L
Larry Lard
Jay said:
How about
If anObject IsA Something Then
reinforcing the "is-a" idea you get in all the OO texts?
J
Jay B. Harlow [MVP - Outlook]
Larry,
I like IsA as a replacement for TypeOf Is!
My only concern, albeit minor, is would a quick glance of the code cause
confusion with the Is operator?
Or would one include IsA with TypeOf?
If TypeOf anObject IsA Something Then
Which would elimate the OP's question in the first place ;-)
Either way I like the IsA operator.
--
Jay [MVP - Outlook]
..NET Application Architect, Enthusiast, & Evangelist
T.S. Bradley - http://www.tsbradley.net
|
| Jay B. Harlow [MVP - Outlook] wrote:
| > They could have used IsTypeOf
| >
| > If IsTypeOf(anObject, Something) Then
| >
| > Although it reads better then the above, I still prefer the TypeOf
operator
| > as is...
|
| How about
|
| If anObject IsA Something Then
|
| reinforcing the "is-a" idea you get in all the OO texts?
|
| --
| Larry Lard
| Replies to group please
|
I like IsA as a replacement for TypeOf Is!
My only concern, albeit minor, is would a quick glance of the code cause
confusion with the Is operator?
Or would one include IsA with TypeOf?
If TypeOf anObject IsA Something Then
Which would elimate the OP's question in the first place ;-)
Either way I like the IsA operator.
--
Jay [MVP - Outlook]
..NET Application Architect, Enthusiast, & Evangelist
T.S. Bradley - http://www.tsbradley.net
|
| Jay B. Harlow [MVP - Outlook] wrote:
| > They could have used IsTypeOf
| >
| > If IsTypeOf(anObject, Something) Then
| >
| > Although it reads better then the above, I still prefer the TypeOf
operator
| > as is...
|
| How about
|
| If anObject IsA Something Then
|
| reinforcing the "is-a" idea you get in all the OO texts?
|
| --
| Larry Lard
| Replies to group please
|
H
Herfried K. Wagner [MVP]
Jay,
.... there must be an 'IsAn' operator too:
\\\
If Person IsAn Employee Then
...
End If
///
SCNR
Jay B. Harlow said:
.... there must be an 'IsAn' operator too:
\\\
If Person IsAn Employee Then
...
End If
///
SCNR
J
Jay B. Harlow [MVP - Outlook]
Herfried,
| > Either way I like the IsA operator.
| ... there must be an 'IsAn' operator too:
*Chuckles*
I was actually thinking the same thing when I responded ;-)
--
Jay [MVP - Outlook]
..NET Application Architect, Enthusiast, & Evangelist
T.S. Bradley - http://www.tsbradley.net
| Jay,
|
| > Or would one include IsA with TypeOf?
| >
| > If TypeOf anObject IsA Something Then
| >
| > Which would elimate the OP's question in the first place ;-)
| >
| > Either way I like the IsA operator.
|
| ... there must be an 'IsAn' operator too:
|
| \\\
| If Person IsAn Employee Then
| ...
| End If
| ///
|
| SCNR
|
| --
| M S Herfried K. Wagner
| M V P <URL:http://dotnet.mvps.org/>
| V B <URL:http://classicvb.org/petition/>
| > Either way I like the IsA operator.
| ... there must be an 'IsAn' operator too:
*Chuckles*
I was actually thinking the same thing when I responded ;-)
--
Jay [MVP - Outlook]
..NET Application Architect, Enthusiast, & Evangelist
T.S. Bradley - http://www.tsbradley.net
| Jay,
|
| > Or would one include IsA with TypeOf?
| >
| > If TypeOf anObject IsA Something Then
| >
| > Which would elimate the OP's question in the first place ;-)
| >
| > Either way I like the IsA operator.
|
| ... there must be an 'IsAn' operator too:
|
| \\\
| If Person IsAn Employee Then
| ...
| End If
| ///
|
| SCNR
|
| --
| M S Herfried K. Wagner
| M V P <URL:http://dotnet.mvps.org/>
| V B <URL:http://classicvb.org/petition/>