McBasic™ 0.7.881 · Build 881 · 8 min read

Hands-on tutorial · Input & events

Keep option groups independent

Build mutually exclusive choices without coupling unrelated decisions.

1 Form / control designs1 complete BASIC filesGuided sample project

Download complete project Complete event code

Group identity matters more than distance on the canvas. Delivery, payment and customer type are independent decisions in this sample. Update the summary from the selected states, and inspect the difference between clicking the already-selected option and changing a value.

Step 1Prepare a safe practice project#

Extract the archive into a new writable folder, separate from your own application. Open OptionGroups.mcproj in McBasic™. Keep every declared source, layout, resource and migration file together.

To reconstruct it yourself, create a DesktopApp project and add the files declared below. In the complete project, follow these steps as a guided rebuild: replace each named source file once and Check after all its procedures are present.

Exact project configuration

OptionGroups.mcproj

{
  "schemaVersion": 1,
  "projectId": "99578971-5863-4082-a627-ec424196595e",
  "name": "OptionGroups",
  "kind": "DesktopApp",
  "language": {
    "dialect": "McBasic1",
    "requireExplicit": true,
    "compare": "Binary",
    "defaultArrayBase": 0
  },
  "application": {
    "bundleIdentifier": "com.mcbasic.optiongroups",
    "version": "0.1.0",
    "buildNumber": "1",
    "startupFormId": "form-main",
    "shutdownMode": "OnStartupFormClosed"
  },
  "forms": [
    {
      "id": "form-main",
      "typeName": "frmMain",
      "layout": "Forms/frmMain.form.json",
      "code": "Forms/frmMain.bas"
    }
  ],
  "modules": [],
  "classes": [],
  "tests": [],
  "references": [],
  "resources": [],
  "targets": [
    "osx-arm64"
  ],
  "capabilities": []
}

Step 2Build the Form and set its properties#

frmMain

Select the Form first and set its properties. Add containers before their children. These are initial Designer values, not statements to paste into a procedure.

Form property	Value
`Caption`	`"Option groups"`
`Width`	`620`
`Height`	`460`

Type	Name	Parent
Panel	`pnlDelivery`	Form
Panel	`pnlPayment`	Form
OptionButton	`optStandard`	pnlDelivery
OptionButton	`optExpress`	pnlDelivery
OptionButton	`optCard`	pnlPayment
OptionButton	`optCash`	pnlPayment
OptionButton	`optPersonal`	Form
OptionButton	`optBusiness`	Form
Label	`lblState`	Form
Label	`lblClick`	Form
CommandButton	`cmdExpress`	Form

pnlDelivery · exact Inspector values

Property	Value
`Left`	`24`
`Top`	`44`
`Width`	`240`
`Height`	`150`
`Enabled`	`True`
`Visible`	`True`
`TabIndex`	`0`
Anchor edges	Left, Top

pnlPayment · exact Inspector values

Property	Value
`Left`	`284`
`Top`	`44`
`Width`	`240`
`Height`	`150`
`Enabled`	`True`
`Visible`	`True`
`TabIndex`	`1`
Anchor edges	Left, Top

optStandard · exact Inspector values

Property	Value
`Left`	`16`
`Top`	`24`
`Width`	`200`
`Height`	`32`
`Enabled`	`True`
`Visible`	`True`
`Caption`	`"Standard delivery"`
`GroupName`	`"delivery"`
`Checked`	`True`
`TabIndex`	`2`
Anchor edges	Left, Top

optExpress · exact Inspector values

Property	Value
`Left`	`16`
`Top`	`72`
`Width`	`200`
`Height`	`32`
`Enabled`	`True`
`Visible`	`True`
`Caption`	`"Express delivery"`
`GroupName`	`"delivery"`
`Checked`	`False`
`TabIndex`	`3`
Anchor edges	Left, Top

optCard · exact Inspector values

Property	Value
`Left`	`16`
`Top`	`24`
`Width`	`200`
`Height`	`32`
`Enabled`	`True`
`Visible`	`True`
`Caption`	`"Card"`
`GroupName`	`"payment"`
`Checked`	`True`
`TabIndex`	`4`
Anchor edges	Left, Top

optCash · exact Inspector values

Property	Value
`Left`	`16`
`Top`	`72`
`Width`	`200`
`Height`	`32`
`Enabled`	`True`
`Visible`	`True`
`Caption`	`"Cash"`
`GroupName`	`"payment"`
`Checked`	`False`
`TabIndex`	`5`
Anchor edges	Left, Top

optPersonal · exact Inspector values

Property	Value
`Left`	`24`
`Top`	`220`
`Width`	`240`
`Height`	`32`
`Enabled`	`True`
`Visible`	`True`
`Caption`	`"Personal account"`
`GroupName`	`"account"`
`Checked`	`True`
`TabIndex`	`6`
Anchor edges	Left, Top

optBusiness · exact Inspector values

Property	Value
`Left`	`284`
`Top`	`220`
`Width`	`240`
`Height`	`32`
`Enabled`	`True`
`Visible`	`True`
`Caption`	`"Business account"`
`GroupName`	`"account"`
`Checked`	`False`
`TabIndex`	`7`
Anchor edges	Left, Top

lblState · exact Inspector values

Property	Value
`Left`	`24`
`Top`	`274`
`Width`	`570`
`Height`	`42`
`Enabled`	`True`
`Visible`	`True`
`Caption`	`"Ready"`
`TabIndex`	`8`
Anchor edges	Left, Top

lblClick · exact Inspector values

Property	Value
`Left`	`24`
`Top`	`320`
`Width`	`570`
`Height`	`32`
`Enabled`	`True`
`Visible`	`True`
`Caption`	`"Choose an option"`
`TabIndex`	`9`
Anchor edges	Left, Top

cmdExpress · exact Inspector values

Property	Value
`Left`	`24`
`Top`	`366`
`Width`	`280`
`Height`	`32`
`Enabled`	`True`
`Visible`	`True`
`Caption`	`"Select express from BASIC"`
`TabIndex`	`10`
Anchor edges	Left, Top

Step 3Connect the events explicitly#

frmMain

Object	Event	Procedure	Parameters
Form	`Load`	`Form_Load`	`()`

Step 4Enter the complete behavior#

Open the named source file. Enter declarations first, then every procedure. Expand a procedure for its full body, or copy the complete file. Helpers are required: do not stop after entering the first Click handler.

`Forms/frmMain.bas`

Enter these declarations at file scope, before the procedures.

Forms/frmMain.bas · declarations

Option Explicit

Private Sub UpdateState()

Enter this helper in the named source file, outside every other procedure. Its callers are included in the same project.

Forms/frmMain.bas · UpdateState

Private Sub UpdateState()
    lblState.Caption = "Express: " & CStr(optExpress.Checked) & "; Cash: " & CStr(optCash.Checked) & "; Business: " & CStr(optBusiness.Checked)
End Sub

Public Sub Form_Load()

Initialize state before enabling dependent actions. Keep the shared declarations and startup dependencies with this procedure.

Forms/frmMain.bas · Form_Load

Public Sub Form_Load()
    cmdExpress.Default = True
    cmdExpress.Cancel = True
    lblClick.Caption = "Named group: " & optStandard.GroupName
    Call UpdateState()
End Sub

Public Sub cmdExpress_Click()

Enter the complete action, including its input checks and calls to helper procedures.

Forms/frmMain.bas · cmdExpress_Click

Public Sub cmdExpress_Click()
    optExpress.Checked = True
End Sub

Public Sub optStandard_Change()

Read the current value or selection and update its dependent interface. The binding above determines which object calls this handler.

Forms/frmMain.bas · optStandard_Change

Public Sub optStandard_Change()
    Call UpdateState()
End Sub

Public Sub optStandard_Click()

Enter the complete action, including its input checks and calls to helper procedures.

Forms/frmMain.bas · optStandard_Click

Public Sub optStandard_Click()
    lblClick.Caption = "Click: optStandard"
End Sub

Public Sub optExpress_Change()

Read the current value or selection and update its dependent interface. The binding above determines which object calls this handler.

Forms/frmMain.bas · optExpress_Change

Public Sub optExpress_Change()
    Call UpdateState()
End Sub

Public Sub optExpress_Click()

Enter the complete action, including its input checks and calls to helper procedures.

Forms/frmMain.bas · optExpress_Click

Public Sub optExpress_Click()
    lblClick.Caption = "Click: optExpress"
End Sub

Public Sub optCard_Change()

Read the current value or selection and update its dependent interface. The binding above determines which object calls this handler.

Forms/frmMain.bas · optCard_Change

Public Sub optCard_Change()
    Call UpdateState()
End Sub

Public Sub optCard_Click()

Enter the complete action, including its input checks and calls to helper procedures.

Forms/frmMain.bas · optCard_Click

Public Sub optCard_Click()
    lblClick.Caption = "Click: optCard"
End Sub

Public Sub optCash_Change()

Read the current value or selection and update its dependent interface. The binding above determines which object calls this handler.

Forms/frmMain.bas · optCash_Change

Public Sub optCash_Change()
    Call UpdateState()
End Sub

Public Sub optCash_Click()

Enter the complete action, including its input checks and calls to helper procedures.

Forms/frmMain.bas · optCash_Click

Public Sub optCash_Click()
    lblClick.Caption = "Click: optCash"
End Sub

Public Sub optPersonal_Change()

Read the current value or selection and update its dependent interface. The binding above determines which object calls this handler.

Forms/frmMain.bas · optPersonal_Change

Public Sub optPersonal_Change()
    Call UpdateState()
End Sub

Public Sub optPersonal_Click()

Enter the complete action, including its input checks and calls to helper procedures.

Forms/frmMain.bas · optPersonal_Click

Public Sub optPersonal_Click()
    lblClick.Caption = "Click: optPersonal"
End Sub

Public Sub optBusiness_Change()

Read the current value or selection and update its dependent interface. The binding above determines which object calls this handler.

Forms/frmMain.bas · optBusiness_Change

Public Sub optBusiness_Change()
    Call UpdateState()
End Sub

Public Sub optBusiness_Click()

Enter the complete action, including its input checks and calls to helper procedures.

Forms/frmMain.bas · optBusiness_Click

Public Sub optBusiness_Click()
    lblClick.Caption = "Click: optBusiness"
End Sub

Copy the complete Forms/frmMain.bas file

Replace the file once; do not append duplicate procedures.

Forms/frmMain.bas

Option Explicit

Private Sub UpdateState()
    lblState.Caption = "Express: " & CStr(optExpress.Checked) & "; Cash: " & CStr(optCash.Checked) & "; Business: " & CStr(optBusiness.Checked)
End Sub

Public Sub Form_Load()
    cmdExpress.Default = True
    cmdExpress.Cancel = True
    lblClick.Caption = "Named group: " & optStandard.GroupName
    Call UpdateState()
End Sub

Public Sub cmdExpress_Click()
    optExpress.Checked = True
End Sub

Public Sub optStandard_Change()
    Call UpdateState()
End Sub

Public Sub optStandard_Click()
    lblClick.Caption = "Click: optStandard"
End Sub

Public Sub optExpress_Change()
    Call UpdateState()
End Sub

Public Sub optExpress_Click()
    lblClick.Caption = "Click: optExpress"
End Sub

Public Sub optCard_Change()
    Call UpdateState()
End Sub

Public Sub optCard_Click()
    lblClick.Caption = "Click: optCard"
End Sub

Public Sub optCash_Change()
    Call UpdateState()
End Sub

Public Sub optCash_Click()
    lblClick.Caption = "Click: optCash"
End Sub

Public Sub optPersonal_Change()
    Call UpdateState()
End Sub

Public Sub optPersonal_Click()
    lblClick.Caption = "Click: optPersonal"
End Sub

Public Sub optBusiness_Change()
    Call UpdateState()
End Sub

Public Sub optBusiness_Click()
    lblClick.Caption = "Click: optBusiness"
End Sub

Step 5Keep resources and storage reproducible#

No external resource or migration files are declared. Any inline migration, seed data or local JSON is present in the code above. Runtime application data and private preferences are not included in the archive.

Step 6Check, run and test the result#

Save all files and run Check. Resolve diagnostics before Run. Developer CLI users can work from the extracted folder:

Developer CLI

mcbasic check OptionGroups.mcproj
mcbasic run OptionGroups.mcproj

Acceptance checklist

Change delivery without changing payment.
Click an already-selected option and compare Click with Change.
Use the Express command to select an option programmatically.

Step 7Make one change and repeat the tests#

Add another delivery choice while preserving the other two groups.

Save a working Git checkpoint first. Change one behavior, Check again and repeat the acceptance checklist. Compare with the downloaded solution if a regression appears.

Source baseline 20f4bfed6b · Build manifest

Keep option groups independent

Step 1Prepare a safe practice project#

Step 2Build the Form and set its properties#

frmMain

Step 3Connect the events explicitly#

frmMain

Step 4Enter the complete behavior#

Forms/frmMain.bas

Step 5Keep resources and storage reproducible#

Step 6Check, run and test the result#

Acceptance checklist

Step 7Make one change and repeat the tests#

Continue learning#

`Forms/frmMain.bas`