This is a very interesting topic - I would love to hear others ideas of
organising source for big projects, and any other web references.
My quick thoughts:
Note as far as the Delphi compiler is concerned it is fine with units of
thousands of lines, its still a one pass compiler, and if the IDE can allow
you to jump to declarations of anything and find references it is still very
usable
However in general there are lots of good reasons to separate UI and any
processing code.
I know of two approaches - Model/View/Controller where UI units events all
call business unit functions of business classes in their own class units,
and all data control details are separate in a datamodule.
Less separated is a UI where all event code is either a bit or very
separated from all involved processing logic.
Even detailed and useful UI additional code can be separated from the UI
(example below)
If I have more than a few lines in an event., I instead move the code into a
separate procedure,
eg a button click might look like:
procedure TfrmJBPleditdb.btnSaveCodeClick(Sender: TObject);
begin
SaveCodeDescList;
end;
Depending on what I want to do this routine might either still be in the
form unit, but already can be called by other events on the form- eg from a
DoubleClick. Once it becomes more generally useful I move it into a
library unit and it can be called from anywhere, probably with more
parameters.
Or it could be an action of which the execute method gets called in an
event - this also provides a way of abstracting the functional code from the
UI unit.
Sometimes such abstracted functionality is still just to do with the UI
even, as an alternative way to making descended components - because the
standard VCL components can be used and extra functions can be easily added
to them only when needed down the track. Here is an example which adds a
search facility to any stringgrid.
procedure Tform1.strgrdSearchKeyDown(Sender: TObject; var Key: Word;
Shift: TShiftState);
begin
if (key = $43) and (ssCtrl in Shift) then
begin
CopyThisLine(strgrdSearch); //CTRL+C
end;
if (key = $46) and (ssCtrl in Shift) then
begin
xcGridFind(strgrdSearch,FindStr,strFound); //CTRL+F
end;
if (key = VK_F3) and not (ssShift in Shift) then
begin
xcGridFindNext(strgrdSearch,FindStr,strFound); //F3
end;
if (key = VK_F3) and (ssShift in Shift) then
begin
xcGridFindPrev(strgrdSearch,FindStr,strFound); //Shift+F3
end;
strgrdSearch.setfocus;
end;
The functions (Copythisline, xcGridFind etc) these call are in a library,
which can be anywhere convenient, either in a class definition/business
logic unit or in a standalone code only unit
eg
procedure xcGridFind(pGrid:TStringGrid;var pFindString:String;var
pFound:Boolean);
var
lrow,lcol,rowptr,colptr,lposn:integer;
testcell:string;
begin
lrow:=pGrid.Row;
lcol:=pGrid.Col;
pFindString:=pGrid.Cells[lcol,lrow]; //default to current cell contents
pFindString:=inputBox('Find:','Text to find:',pFindString);
pFound:=false;
if pFindstring='' then exit;
for rowptr := lrow+1 to pGrid.rowCount - 1 do
begin
if rowptr>= pGrid.RowCount-1 then break;
for colptr := 0 to pGrid.ColCount - 1 do
begin
testcell:=pGrid.Cells[colptr,rowptr];
xcstrin(testcell,pFindstring,lposn,1); //this is a wrapper
for AnsiPos making it non case-sensitive
if lposn>0 then
begin
pFound:=true;
break;
end;
end; //col
if pFound=true then break;
end; //row
if pFound then
begin
pGrid.Row:=rowptr; //position at the found cell
pGrid.col:=colptr;
end;
end;
In my case some of these library units might easily be 10000 lines+, but its
not an issue either to me or the compiler, I can find stuff easily and the
compiler only compiles and links the functions or procedures required, all
I have to do is add a useful library unit to the uses clause.
John
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