Crystal 8 UDF's

> ----- Original Message -----
>; From: "Rob Kennedy&quot; < rkennedy%40cs.wisc.edu">rkennedycs.wisc.edu>
&gt; To: delphi-en%40yahoogroups.com">delphi-enyahoogroups.com
&gt; Subject: Re: [delphi-en] Crystal 8 UDF's
>; Date: Mon, 13 Nov 2006 09:53:44 -0600 (CST)
>;
>
> Paul Bennett wrote:
&gt; > I am trying to create a Crystal 8 User Defined Function dll which
>; > takes a single integer as a parameter and packs that integer up into
> > a broadcast Message as the wparam parameter.
> >
> > My code is shown below.
&gt; >
> > function LaunchApplication (ParamBlock : PUFParamBlock) : UFError;
>
> Is this the function exported by your DLL? It should probably use the
> stdcall calling convention, not register.
>
> > var Param1 : PUFParamListElement; //a pointer to the first parameter
> > var n : integer;
> > fWakeup : Cardinal;
> > MyWakeup: PChar;
&gt; > begin
>; > Param1 := GetParam (ParamBlock, 1); //the first param is the AppID
>; > to launch
&gt; > //check if the correct number of parameters is passed to our
> > function
> >
> > if (Param1 = nil) then
> > begin
>; > MyWakeup := Error;
&gt; > fWakeup := RegisterWindowMessage(MyWakeup);
> > If fWakeup <> 0 Then
> > nResult := PostMessage(hWnd_BROADCAST, fWakeUp, n, n);
>
> What is the value of n?

n Is an integer value which should have been passed int to the function from Crystal

> Why are you storing an error string in a variable named fWakeup, as though
&gt; it's the same status the wakeup message you store in that variable later?
&gt; Go ahead and use different variables with appropriate names. It will make
> the code easier to read.

Your right, Error should have been declared as a PChar, it is basically another (different) string used to generate a Unique Windows Message ID.

>; And what is nResult?

nResult is just a holder to contain the result of the postmessage method (and should have been declared in the var block).

>
> --
> Rob

re-writing the Error check below may be clearer
var
MyErrorID: PChar;
fError : Cardinal
....
if (Param1 = nil) then
begin
MyErrorID := Error;
fError := RegisterWindowMessage(MyErrorID);
If fError <> 0 Then // fError is valid Message #
nResult := PostMessage(hWnd_BROADCAST, fError, n, n);

I don't think either of those oversights are the problem though, it would seem that the call to PostMessage(hWnd_BROADCAST, fWakeUp, n, n) is not passing the integer variable 'n'

Regardless of which message handler I use in the eventual target I get a value of 0 in both parameter positions.

Experience is something you don't get until just after you need it.

--
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.

Paul Bennett wrote:
&gt;>> var Param1 : PUFParamListElement; //a pointer to the first parameter
>>&gt; var n : integer;
>>>; fWakeup : Cardinal;
>>&gt; MyWakeup: PChar;
&gt;>> begin
>;>> Param1 := GetParam (ParamBlock, 1); //the first param is the AppID
>;>> to launch
&gt;>> //check if the correct number of parameters is passed to our
>&gt;> function
>>>;
>>> if (Param1 = nil) then
>>> begin
>;>> MyWakeup := Error;
&gt;>> fWakeup := RegisterWindowMessage(MyWakeup);
>>;> If fWakeup <> 0 Then
>>> nResult := PostMessage(hWnd_BROADCAST, fWakeUp, n, n);
>&gt;
>&gt; What is the value of n?
>
> n Is an integer value which should have been passed int to the function
> from Crystal

Read my question again.

You do have all compiler hints and warnings enabled, don't you?

&gt; re-writing the Error check below may be clearer
&gt; var
> MyErrorID: PChar;
&gt; fError : Cardinal
> ....
> if (Param1 = nil) then
> begin
>; MyErrorID := Error;
&gt; fError := RegisterWindowMessage(MyErrorID);
> If fError <> 0 Then // fError is valid Message #
> nResult := PostMessage(hWnd_BROADCAST, fError, n, n);
>
> I don't think either of those oversights are the problem though, it would
>; seem that the call to PostMessage(hWnd_BROADCAST, fWakeUp, n, n) is not
> passing the integer variable 'n'

It's passing the value in that variable, but what, exactly, should that
value be?

>; Regardless of which message handler I use in the eventual target I get a
> value of 0 in both parameter positions.

What value were you expecting, and why?

--
Rob

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.

Just a comment to hopefully help (and I might be going off wildly on the
wrong tangent here,) but it appears to me that there's a
misunderstanding below: Rob is asking what the value of n is (implying,
as I read him, that it's undefined.) However its value would be the
value of the first parameter passed to the report (I think), and is set
in the line reading:

n := Param1.Parameter.ParamInteger;

Unfortunately this line was trimmed off which might've given the
impression that n is not set anywhere, giving rise to the
misunderstanding. (Or, as I say, I'm barking up entirely the wrong tree
)

Walter

Rob Kennedy wrote:
&gt;
>
&gt; >>&gt; nResult := PostMessage(hWnd_BROADCAST, fWakeUp, n, n);
> >>
> >> What is the value of n?
> >
> > n Is an integer value which should have been passed int to the function
> > from Crystal
&gt;
> Read my question again.
>

[Non-text portions of this message have been removed]

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.

Walter Prins wrote:
&gt; Just a comment to hopefully help (and I might be going off wildly on the
> wrong tangent here,) but it appears to me that there's a
> misunderstanding below: Rob is asking what the value of n is (implying,
> as I read him, that it's undefined.) However its value would be the
> value of the first parameter passed to the report (I think), and is set
> in the line reading:
>
> n := Param1.Parameter.ParamInteger;
>
> Unfortunately this line was trimmed off which might've given the
> impression that n is not set anywhere, giving rise to the
> misunderstanding. (Or, as I say, I'm barking up entirely the wrong tree
> )

It was trimmed off _below_ the line I asked about, not above.

There's also still the question about calling conventions.

--
Rob

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.

Aha! So I *was* barking up qutie the wrong tree... live and learn eh.
Will teach me to be more careful next time.

Thanks

Walter

Rob Kennedy wrote:
&gt;
> It was trimmed off _below_ the line I asked about, not above.
&gt;
> There's also still the question about calling conventions.
>

[Non-text portions of this message have been removed]

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.