How to call a procedure, from a procedure

[stephanos]

Dear All

I have written a playlist programme for my mp3 player in Lazarus 2.0.8.  It opens an M3U file on the player and writes the content to a Memo

Code: Pascal  [Select][+][-]

1. Memo1.Lines.LoadFromFile('PlayListStephen.m3u');

After which it closes the file.  When the Memo window is updated with new content the content is saved to the file using a Save button.  Then I press an Exit button to leave the programme.

The improvement I want to make is to make Exit call Save, save, then exit.  Simple I thought.  From within the Exit onClick event I simply type: “BitBtn5Click();” - see below.

Code: Pascal  [Select][+][-]

1. procedure TForm1.BitBtn1Click(Sender: TObject);
2. begin
3.   BitBtn5Click();
4.   Close;
5. end;  
6.  

This should call the Save button

Code: Pascal  [Select][+][-]

1. procedure TForm1.BitBtn5Click(Sender: TObject);
2. begin
3.        Lots of code to do with saving the Memo1 content
4. end;
5.  

But no, this is not the way.  On Compile I get this error message:
“Compile Project, Target: SimpleForms.exe: Exit code 1, Errors: 2, Hints: 1
simpleformsunit.pas(48,64) Hint: Parameter "Value" not used
simpleformsunit.pas(338,17) Error: Wrong number of parameters specified for call to "BitBtn5Click"
simpleformsunit.pas(176,18) Error: Found declaration: BitBtn5Click(TObject);”

According to lots of places, what I have done is correct.

Any help appreciated

[ccrause]

8<
The improvement I want to make is to make Exit call Save, save, then exit.  Simple I thought.  From within the Exit onClick event I simply type: “BitBtn5Click();” - see below.

Code: Pascal  [Select][+][-]

1. procedure TForm1.BitBtn1Click(Sender: TObject);
2. begin
3.   BitBtn5Click();
4.   Close;
5. end;  
6.  

8<

But no, this is not the way.  On Compile I get this error message:
“Compile Project, Target: SimpleForms.exe: Exit code 1, Errors: 2, Hints: 1
simpleformsunit.pas(48,64) Hint: Parameter "Value" not used
simpleformsunit.pas(338,17) Error: Wrong number of parameters specified for call to "BitBtn5Click"
simpleformsunit.pas(176,18) Error: Found declaration: BitBtn5Click(TObject);”

The compiler is telling you exactly what is missing: the parameter to the method BitBtn5Click.  In code:

Code: Pascal  [Select][+][-]

1. procedure TForm1.BitBtn1Click(Sender: TObject);
2. begin
3.   BitBtn5Click(Sender); // or BitBtn5Click(nil) may also work if you don't use the Sender parameter
4.   Close;
5. end;

According to lots of places, what I have done is correct.

[Remy Lebeau]

Code: Pascal  [Select][+][-]

1. procedure TForm1.BitBtn1Click(Sender: TObject);
2. begin
3.   BitBtn5Click(Sender); // or BitBtn5Click(nil) may also work if you don't use the Sender parameter
4.   Close;
5. end;

Unless BitBtn5Click() is actually using its own Sender parameter, I would pass nil:

Code: Pascal  [Select][+][-]

1. procedure TForm1.BitBtn1Click(Sender: TObject);
2. begin
3.   BitBtn5Click(nil);
4.   Close;
5. end;

The alternative would be to call the button's Click() method instead, and let it call the OnClick handler:

Code: Pascal  [Select][+][-]

1. procedure TForm1.BitBtn1Click(Sender: TObject);
2. begin
3.   BitBtn5.Click;
4.   Close;
5. end;

Though,  a better design would be to separate the save logic to its own method that multiple UI handlers can call when needed, eg:

Code: Pascal  [Select][+][-]

1. procedure TForm1.BitBtn1Click(Sender: TObject);
2. begin
3.   Save;
4.   Close;
5. end;  
6.      
7. procedure TForm1.BitBtn5Click(Sender: TObject);
8. begin
9.   Save;
10. end;
11.  
12. procedure TForm1.Save;
13. begin
14.   // Lots of code to do with saving the Memo1 content
15. end;

[stephanos14]

Dear All

Thanks, that works.  I will do some research on the last suggestion about method.

Meanwhile, it has highlighted another problem which I will post to the "Using the Lazarus IDE".