Using combo box to select what paths and registry keys to use - inno-setup

Question

Purpose:
With Inno Setup I want to create an installer with a dropdown list in the install wizard.
The choice made in the wizards defines 2 variables:
One for the folder location and the other for the location in the registry.
Problem:
Variables are defined as global in [Code], but are not used in [Files] and [Registry]
Code:
The two variables are: strData1 & strData2
I was trying to retrieve them with functions: strData1returner & strData2returner
[Setup]
...
[Dirs]
Name: "C:\Program Files\CompanyName\{code:strData1returner}"
[Files]
Source: "C:\SomeDll.dll"; \
DestDir: "C:\Program Files\CompanyName\{code:strData1returner}\"; Flags: ignoreversion;
[Registry]
Root: HKCU; subkey: "{code:strData2returner}"; flags: createvalueifdoesntexist
[Code]
var
Button: TNewButton;
ComboBox: TNewComboBox;
CustomPage: TWizardPage;
strData1: string;
strData2: string;
procedure ComboBoxChange(Sender: TObject);
begin
case ComboBox.ItemIndex of
0:
begin
strData1 := 'Subfolder';
strData2 := 'SOFTWARE\CompanyName';
end;
end;
end;
procedure InitializeWizard;
var
DescLabel: TLabel;
begin
CustomPage := CreateCustomPage(wpSelectDir, 'Caption', 'Description');
DescLabel := TLabel.Create(WizardForm);
DescLabel.Parent := CustomPage.Surface;
DescLabel.Left := 0;
DescLabel.Top := 0;
DescLabel.Caption := 'Select an item...';
ComboBox := TNewComboBox.Create(WizardForm);
ComboBox.Parent := CustomPage.Surface;
ComboBox.Left := 0;
ComboBox.Top := DescLabel.Top + DescLabel.Height + 6;
ComboBox.Width := 220;
ComboBox.Style := csDropDownList;
ComboBox.Items.Add('Choice1');
ComboBox.ItemIndex := 0;
ComboBox.OnChange := #ComboBoxChange;
end;
function strData1returner(Param: String): String;
begin
Result := strData1;
end;
function strData2returner(Param: String): String;
begin
Result := strData2;
end;

Answer 1

There was only a single option: "Choice1" - So I added a second (Choice2), and alternative values for that second option, under index 1.
You should also initialize the two variables in InitializeWizard, in case the user doesn't change the combobox value. The ComboBoxChange procedure is only executed when the value actually changes, not when the default is accepted via no action.
Also, in trying to reproduce your problem I noticed a syntax problem causing compilation errors with createvalueifdoesntexistcreatevalueifdoesntexist - naturally, you just need one of those.
[Dirs]
Name: "C:\Program Files\CompanyName\{code:strData1returner}"
[Files]
Source: "C:\SomeDll.dll"; DestDir: "C:\Program Files\CompanyName\{code:strData1returner}\"; Flags: ignoreversion;
[Registry]
Root: HKCU; subkey:"{code:strData2returner}"; flags: createvalueifdoesntexist
[Code]
var
Button: TNewButton;
ComboBox: TNewComboBox;
CustomPage: TWizardPage;
strData1: string;
strData2: string;
procedure ComboBoxChange(Sender: TObject);
begin
case ComboBox.ItemIndex of
0:
begin
strData1 := 'Subfolder';
strData2 := 'SOFTWARE\CompanyName';
end;
1:
begin
strData1 := 'Subfolder2';
strData2 := 'SOFTWARE\CompanyName2';
end;
end;
end;
procedure InitializeWizard;
var
DescLabel: TLabel;
begin
CustomPage := CreateCustomPage(wpSelectDir, 'Caption', 'Description');
DescLabel := TLabel.Create(WizardForm);
DescLabel.Parent := CustomPage.Surface;
DescLabel.Left := 0;
DescLabel.Top := 0;
DescLabel.Caption := 'Select an item...';
ComboBox := TNewComboBox.Create(WizardForm);
ComboBox.Parent := CustomPage.Surface;
ComboBox.Left := 0;
ComboBox.Top := DescLabel.Top + DescLabel.Height + 6;
ComboBox.Width := 220;
ComboBox.Style := csDropDownList;
ComboBox.Items.Add('Choice1');
ComboBox.Items.Add('Choice2');
ComboBox.ItemIndex := 0;
ComboBox.OnChange := #ComboBoxChange;
strData1 := 'Subfolder';
strData2 := 'SOFTWARE\CompanyName';
end;
function strData1returner(Param: String): String;
begin
Result := strData1;
end;
function strData2returner(Param: String): String;
begin
Result := strData2;
end;
The code above is working as I think you expect it to here.

Answer 2

Actually your attempt to use global variables just complicates the code.
Access the ComboBox.ItemIndex directly from scripted constant implementations like:
[Dirs]
Name: "{app}\{code:GetSelectedSubfolder}"
[Files]
Source: "C:\SomeDll.dll"; DestDir: "{app}\{code:GetSelectedSubfolder}"
[Registry]
Root: HKCU; Subkey: "{code:GetSelectedSubkey}"
[Code]
var
ComboBox: TNewComboBox;
procedure InitializeWizard;
{ ... }
begin
{ ... }
ComboBox := TNewComboBox.Create(WizardForm);
{ ... }
ComboBox.Items.Add('Choice1');
ComboBox.Items.Add('Choice2');
ComboBox.ItemIndex := 0;
end;
function GetSelectedSubfolder(Param: String): String;
begin
case ComboBox.ItemIndex of
0: Result := 'Subfolder1';
1: Result := 'Subfolder2';
end;
end;
function GetSelectedSubkey(Param: String): String;
begin
case ComboBox.ItemIndex of
0: Result := 'SOFTWARE\CompanyName1';
1: Result := 'SOFTWARE\CompanyName2';
end;
end;

Answer 3

You can create global variables like this:
#define CustomVarName "Value"
More specific information about here: #define