I'd tend to agree factory methods can be very helpful in simplifying code.
Alister Christie
Computers for People
Ph: 04 471 1849 Fax: 04 471 1266
http://www.salespartner.co.nz
PO Box 13085
Johnsonville
Wellington
Neven MacEwan wrote:
You guys don't consider a constructor a function then?
Jeremy Coulter wrote:
Hi All. This is a question that might be infulenced by some serious
lack of sleep :-)
I have a funtion. Its return result is a TStringlist.
In my code I create a TStringlist then add my values to it, then pass
this to the RESULT varaible for the function.
Now,
Hi Jeremy,
I think you need this one http://v.mahon.free.fr/pro/freeware/memcheck
;-)
Regards
Leigh
www.smootharm.com
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Jeremy Coulter
Sent: Friday, 4 May 2007 1:28 p.m.
To: delphi@delphi.org.nz
Group - Delphi List
Subject: RE: [DUG] Dumb Friday Question
Hi Jeremy,
I think you need this one http://v.mahon.free.fr/pro/freeware/memcheck
;-)
Regards
Leigh
www.smootharm.com
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf
of the above issue.
Myles.
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
On Behalf Of Judd, Struan (eCargo)
Sent: Friday, 4 May 2007 01:46
To: [EMAIL PROTECTED]; NZ Borland Developers Group - Delphi List
Subject: RE: [DUG] Dumb Friday Question
Jeremy Coulter wrote:
Hi All
] On
Behalf Of Leigh Wanstead
Sent: Friday, May 04, 2007 1:55 PM
To: [EMAIL PROTECTED]; NZ Borland Developers Group - Delphi List
Subject: RE: [DUG] Dumb Friday Question
Hi Jeremy,
I think you need this one http://v.mahon.free.fr/pro/freeware/memcheck
;-)
Regards
Leigh
Hi
Your code would leak. You are creating an object and not freeing it.
The calling function that retrieves the result must handle the freeing
of the object.
It might be clearer if you just change the function to a procedure that
takes a TStringList as a parameter. i.e
//Replacement
I would go along with Robert, you should not return complex types from
functions that create them, It makes the code messy, you create it in
one place and free it in another. Any sort of code analyser would also
complain about this. You could return a string = stringlist.text and
assign it
I would endorse Rob's answer here.
I don't consider it just a question of potential leaks, it's about
making the intentions of your code clear.
The intention of who has the responsibility for object lifetime is much,
much clearer in Delphi if your caller creates the Stringlist that it
wants
You guys don't consider a constructor a function then?
I think its totally stylistic, if you want to have functions returning
objects fine, just make it plain that they do,
IMHO
Neven
I would endorse Rob's answer here.
I don't consider it just a question of potential leaks, it's about
David asked:
Surely you are joking?
Is that right? Delphi.NET doesn't have garbage collection?
Yes, it does. I'm guessing they're referring to the IDispose interface
and pattern which Delphi.NET automagically maps calls to Free onto so
that resources _other_ then memory get released early.
PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Xander (GMail)
Sent: Friday, 4 May 2007 2:02 p.m.
To: 'NZ Borland Developers Group - Delphi List'
Subject: RE: [DUG] Dumb Friday Question
Jeremy,
If the function returns a TStringList then it should be the responsibility
of the caller
-Original Message-
From: [EMAIL PROTECTED] [mailto:delphi-
[EMAIL PROTECTED] On Behalf Of Neven MacEwan
Sent: Friday, 4 May 2007 2:45 p.m.
To: NZ Borland Developers Group - Delphi List
Subject: Re: [DUG] Dumb Friday Question
You guys don't consider a constructor a function
I do consider a constructor a function to some extent, but it's a
function which has compiler support.
I.e. the compiler guarantees to tidy up a partially constructed result
object if an exception gets raised in the constructor.
Also, everybody knows that a constructor returns a complex object;
Note for clarity, although I think we all understand this anyway.
What we're talking about here is a function returning _and handing off_
an object.
This is different to exposing an object (e.g. a StringList) as a
property of a class, e.g. the Items property of a combobox or similar.
In that
Warm fuzzy feelings :)
Rob Martin
Software Engineer
phone +64 03 377 0495
fax +64 03 377 0496
web www.chreos.com
Wild Software Ltd
Rohit Gupta wrote:
I would go along with Robert, you should not return complex types from
functions that create them, It makes the code messy, you create
That code's safe from a memory POV, but I wouldn't have coded it like
that personally, because to me, the intentions aren't clear. I believe
that the fact that you had to go and look at the implementation supports
my suggestion of trying to clarify intentions.
I haven't used TFindFile (so
You guys don't consider a constructor a function then?
I think its totally stylistic, if you want to have functions returning
objects fine, just make it plain that they do,
IMHO
Neven
The downside to having creator functions returning objects is that you
have to duplicate the code in
you have to duplicate the code in TObject.Create to ensure safety
What I meant was the ClassHandleException code which runs when an exception
occurs during a constructor.
Cheers,
Carl
___
NZ Borland Developers Group - Delphi mailing list
Post:
Hi
The solution is to use interfaces, but if you don't it would be
difficult to implement a factory pattern
There is this thing in OO language users which seems to be the muddy
area between scalars and objects,
ie is a TStringList a simple object or a complex scalar, of course it
doesn't help
: Friday, 4 May 2007 12:22 PM
To: [EMAIL PROTECTED]; NZ Borland Developers Group - Delphi List
Subject: Re: [DUG] Dumb Friday Question
I would go along with Robert, you should not return complex types from
functions that create them, It makes the code messy, you create it in
one place and free
-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Tim Jarvis
Sent: Friday, 4 May 2007 4:30 p.m.
To: NZ Borland Developers Group - Delphi List; [EMAIL PROTECTED]
Subject: RE: [DUG] Dumb Friday Question
Hi Guys,
Hope you don't mind me sticking my nose in here. Firstly I agree
]
On Behalf Of Rohit Gupta
Sent: Friday, 4 May 2007 12:22 PM
To: [EMAIL PROTECTED]; NZ Borland Developers Group - Delphi List
Subject: Re: [DUG] Dumb Friday Question
I would go along with Robert, you should not return complex types from
functions that create them, It makes the code messy, you
,
Carl
_
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Tim Jarvis
Sent: Friday, May 04, 2007 4:30 PM
To: NZ Borland Developers Group - Delphi List; [EMAIL PROTECTED]
Subject: RE: [DUG] Dumb Friday Question
Hi Guys,
Hope you don't mind me sticking my nose in here
Tim Jarvis [EMAIL PROTECTED] wrote:
Firstly I agree with the sentiment that you should try and avoid
creating objects
in one place and freeing in another ...
This whole discussion is close to my heart. I've got a similar horrible
situation where I've got a factory that produce objects
Giovanni
If the sun is shining in palmy its probably 4 below 0
You should definatetly be using intefaces not pointer for this this way
you can do reference counting
Neven
Tim Jarvis [EMAIL PROTECTED] wrote:
Firstly I agree with the sentiment that you should try and avoid
creating
PROTECTED]
On Behalf Of Neven MacEwan
Sent: Friday, 4 May 2007 05:13
To: NZ Borland Developers Group - Delphi List
Subject: Re: [DUG] Dumb Friday Question
Giovanni
If the sun is shining in palmy its probably 4 below 0
You should definatetly be using intefaces not pointer for this this way
you can do
- I was there for a few years (a long time ago).
Myles.
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
On Behalf Of Neven MacEwan
Sent: Friday, 4 May 2007 05:13
To: NZ Borland Developers Group - Delphi List
Subject: Re: [DUG] Dumb Friday Question
Giovanni
.
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
On Behalf Of Neven MacEwan
Sent: Friday, 4 May 2007 05:49
To: NZ Borland Developers Group - Delphi List
Subject: Re: [DUG] Dumb Friday Question
Myles
As you said its better than nothing but if you really want to do some
May 2007 3:00 PM
To: 'NZ Borland Developers Group - Delphi List'; [EMAIL PROTECTED]
Subject: RE: [DUG] Dumb Friday Question
It isn't different, but that's because:
List := TStringList.Create;
PopulateList(List);
try
if List.Count 0 then
begin
...do lots of stuff
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