Is it safe to make a method that returns a match collection or nothing? or
is it better to just return a match collection and have the code outside the
method validate that match collection is empty or not?
10  2049 
On 2008-10-15, Andy B <a_*****@sbcglobal.netwrote:
Is it safe to make a method that returns a match collection or nothing? or
is it better to just return a match collection and have the code outside the
method validate that match collection is empty or not?
Personally, I prefere when a method returns an empty collection then if it
returns nothing. Returning a null collection (Nothing in VB), usually
complicates the client code - because now you need to do checks to avoid a
NullReferenceException. For example (Warning Air Code!):
' method returns a null (nothing) collection
Dim theCollection As List<SomeEntity= GetCollection()
If Not theCollection Is Nothing Then
For Each e As SomeEntity In theCollection
' do stuff
Next
End If
' method returns an empty collection
For Each e As SomeEntity In GetCollection()
' do stuff
Next
Anyway, there you have it :)
--
Tom Shelton
So I shouldn't be doing something like:
dim matches as MatchCollection = ReturnMatches(stuff)
if matches is nothing
return nothing
else
return matches
Instead I should:
return (matches as MatchCollection = ReturnMatches(stuff))
"Tom Shelton" <to*********@comcastXXXXXXX.netwrote in message
news:QJ******************************@comcast.com. ..
On 2008-10-15, Andy B <a_*****@sbcglobal.netwrote:
>Is it safe to make a method that returns a match collection or nothing?
or
is it better to just return a match collection and have the code outside
the
method validate that match collection is empty or not?
Personally, I prefere when a method returns an empty collection then if it
returns nothing. Returning a null collection (Nothing in VB), usually
complicates the client code - because now you need to do checks to avoid a
NullReferenceException. For example (Warning Air Code!):
' method returns a null (nothing) collection
Dim theCollection As List<SomeEntity= GetCollection()
If Not theCollection Is Nothing Then
For Each e As SomeEntity In theCollection
' do stuff
Next
End If
' method returns an empty collection
For Each e As SomeEntity In GetCollection()
' do stuff
Next
Anyway, there you have it :)
--
Tom Shelton
On Wed, 15 Oct 2008 14:11:17 -0400, "Andy B" <a_*****@sbcglobal.net>
wrote:
>Is it safe to make a method that returns a match collection or nothing? or
is it better to just return a match collection and have the code outside the
method validate that match collection is empty or not?
Always returning a collection (empty if nothing found) may make it
less likely that calling code will be written incorrectly. If you
return Nothing and a caller fails to check for Nothing an exception
will occur.
If you always return a collection, then depending on how the method
works, returning an empty collection might mean that it will be
necessary to create an empty collection that would not have to be
created if Nothing was returned.
So there might be a trade-off between safer code and creating more
objects.
If it were me I would probably return Nothing, and define the method
as returning either Nothing or a non-empty collection so that callers
don't have to make two tests to check if anything was returned.
On 2008-10-16, Jack Jackson <jj******@cinnovations.netwrote:
On Wed, 15 Oct 2008 14:11:17 -0400, "Andy B" <a_*****@sbcglobal.net>
wrote:
>>Is it safe to make a method that returns a match collection or nothing? or
is it better to just return a match collection and have the code outside the
method validate that match collection is empty or not?
Always returning a collection (empty if nothing found) may make it
less likely that calling code will be written incorrectly. If you
return Nothing and a caller fails to check for Nothing an exception
will occur.
If you always return a collection, then depending on how the method
works, returning an empty collection might mean that it will be
necessary to create an empty collection that would not have to be
created if Nothing was returned.
So there might be a trade-off between safer code and creating more
objects.
If it were me I would probably return Nothing, and define the method
as returning either Nothing or a non-empty collection so that callers
don't have to make two tests to check if anything was returned.
How often do you check to see if a collection is empty? Really... In most
cases, your going to loop over it and do stuff. You don't have to check for
an empty collection to loop, but you do have to check for a Nothing. Nope,
returning the empty collection is usually the right thing.
In general, returning the empty collection is going to make the calling code,
simpler and more maintainable.
--
Tom Shelton
On 2008-10-16, Andy B <a_*****@sbcglobal.netwrote:
So I shouldn't be doing something like:
dim matches as MatchCollection = ReturnMatches(stuff)
if matches is nothing
return nothing
else
return matches
Instead I should:
return (matches as MatchCollection = ReturnMatches(stuff))
ReturnMatches(stuff) should be returning a MatchCollection - even if there are
no matches.
--
Tom Shelton
How do you define it to return MatchCollection or nothing?
"Jack Jackson" <jj******@cinnovations.netwrote in message
news:mo********************************@4ax.com...
On Wed, 15 Oct 2008 14:11:17 -0400, "Andy B" <a_*****@sbcglobal.net>
wrote:
>>Is it safe to make a method that returns a match collection or nothing? or
is it better to just return a match collection and have the code outside
the
method validate that match collection is empty or not?
Always returning a collection (empty if nothing found) may make it
less likely that calling code will be written incorrectly. If you
return Nothing and a caller fails to check for Nothing an exception
will occur.
If you always return a collection, then depending on how the method
works, returning an empty collection might mean that it will be
necessary to create an empty collection that would not have to be
created if Nothing was returned.
So there might be a trade-off between safer code and creating more
objects.
If it were me I would probably return Nothing, and define the method
as returning either Nothing or a non-empty collection so that callers
don't have to make two tests to check if anything was returned.
I meant that you document the method as operating that way.
However, Tom has a good point and I think always returning a
collection is probably better.
On Thu, 16 Oct 2008 06:38:56 -0400, "Andy B" <a_*****@sbcglobal.net>
wrote:
>How do you define it to return MatchCollection or nothing?
"Jack Jackson" <jj******@cinnovations.netwrote in message
news:mo********************************@4ax.com.. .
>On Wed, 15 Oct 2008 14:11:17 -0400, "Andy B" <a_*****@sbcglobal.net>
wrote:
>>>Is it safe to make a method that returns a match collection or nothing? or
is it better to just return a match collection and have the code outside
the
method validate that match collection is empty or not?
Always returning a collection (empty if nothing found) may make it
less likely that calling code will be written incorrectly. If you
return Nothing and a caller fails to check for Nothing an exception
will occur.
If you always return a collection, then depending on how the method
works, returning an empty collection might mean that it will be
necessary to create an empty collection that would not have to be
created if Nothing was returned.
So there might be a trade-off between safer code and creating more
objects.
If it were me I would probably return Nothing, and define the method
as returning either Nothing or a non-empty collection so that callers
don't have to make two tests to check if anything was returned.
How do you return null collections?
"Jack Jackson" <jj******@cinnovations.netwrote in message
news:2p********************************@4ax.com...
>I meant that you document the method as operating that way.
However, Tom has a good point and I think always returning a
collection is probably better.
On Thu, 16 Oct 2008 06:38:56 -0400, "Andy B" <a_*****@sbcglobal.net>
wrote:
>>How do you define it to return MatchCollection or nothing?
"Jack Jackson" <jj******@cinnovations.netwrote in message
news:mo********************************@4ax.com. ..
>>On Wed, 15 Oct 2008 14:11:17 -0400, "Andy B" <a_*****@sbcglobal.net>
wrote:
Is it safe to make a method that returns a match collection or nothing?
or
is it better to just return a match collection and have the code outside
the
method validate that match collection is empty or not?
Always returning a collection (empty if nothing found) may make it
less likely that calling code will be written incorrectly. If you
return Nothing and a caller fails to check for Nothing an exception
will occur.
If you always return a collection, then depending on how the method
works, returning an empty collection might mean that it will be
necessary to create an empty collection that would not have to be
created if Nothing was returned.
So there might be a trade-off between safer code and creating more
objects.
If it were me I would probably return Nothing, and define the method
as returning either Nothing or a non-empty collection so that callers
don't have to make two tests to check if anything was returned.
I don't think "null collection" has any meaning.
You can return Nothing or you can return an empty collection (create a
collection but don't add anything to it).
On Thu, 16 Oct 2008 18:26:00 -0400, "Andy B" <a_*****@sbcglobal.net>
wrote:
>How do you return null collections?
"Jack Jackson" <jj******@cinnovations.netwrote in message
news:2p********************************@4ax.com.. .
>>I meant that you document the method as operating that way.
However, Tom has a good point and I think always returning a
collection is probably better.
On Thu, 16 Oct 2008 06:38:56 -0400, "Andy B" <a_*****@sbcglobal.net>
wrote:
>>>How do you define it to return MatchCollection or nothing?
"Jack Jackson" <jj******@cinnovations.netwrote in message
news:mo********************************@4ax.com ...
On Wed, 15 Oct 2008 14:11:17 -0400, "Andy B" <a_*****@sbcglobal.net>
wrote:
>Is it safe to make a method that returns a match collection or nothing?
>or
>is it better to just return a match collection and have the code outside
>the
>method validate that match collection is empty or not?
Always returning a collection (empty if nothing found) may make it
less likely that calling code will be written incorrectly. If you
return Nothing and a caller fails to check for Nothing an exception
will occur.
If you always return a collection, then depending on how the method
works, returning an empty collection might mean that it will be
necessary to create an empty collection that would not have to be
created if Nothing was returned.
So there might be a trade-off between safer code and creating more
objects.
If it were me I would probably return Nothing, and define the method
as returning either Nothing or a non-empty collection so that callers
don't have to make two tests to check if anything was returned.
Ok...
"Jack Jackson" <jj******@cinnovations.netwrote in message
news:pm********************************@4ax.com...
>I don't think "null collection" has any meaning.
You can return Nothing or you can return an empty collection (create a
collection but don't add anything to it).
On Thu, 16 Oct 2008 18:26:00 -0400, "Andy B" <a_*****@sbcglobal.net>
wrote:
>>How do you return null collections?
"Jack Jackson" <jj******@cinnovations.netwrote in message
news:2p********************************@4ax.com. ..
>>>I meant that you document the method as operating that way.
However, Tom has a good point and I think always returning a
collection is probably better.
On Thu, 16 Oct 2008 06:38:56 -0400, "Andy B" <a_*****@sbcglobal.net>
wrote:
How do you define it to return MatchCollection or nothing?
"Jack Jackson" <jj******@cinnovations.netwrote in message
news:mo********************************@4ax.co m...
On Wed, 15 Oct 2008 14:11:17 -0400, "Andy B" <a_*****@sbcglobal.net>
wrote:
>
>>Is it safe to make a method that returns a match collection or
>>nothing?
>>or
>>is it better to just return a match collection and have the code
>>outside
>>the
>>method validate that match collection is empty or not?
>
Always returning a collection (empty if nothing found) may make it
less likely that calling code will be written incorrectly. If you
return Nothing and a caller fails to check for Nothing an exception
will occur.
>
If you always return a collection, then depending on how the method
works, returning an empty collection might mean that it will be
necessary to create an empty collection that would not have to be
created if Nothing was returned.
>
So there might be a trade-off between safer code and creating more
objects.
>
If it were me I would probably return Nothing, and define the method
as returning either Nothing or a non-empty collection so that callers
don't have to make two tests to check if anything was returned.
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