Challenge: A Self-Replicating App

William Lancee · Apr 13, 2020

@Sandman, I did not mean to make light of the situation, simply to entertain and inspire while we are stuck.

Although I am online most of the time, I did not respond earlier because over here, the day is just starting, and I was asleep.

@LucaMs, at least I got a reaction, so hard to get with all this social distancing. My version has only 2 Subs. I'll post it later today.

sorex · Apr 13, 2020

I didn't look at UDG's file yet so what is it supposed to do?

LucaMs · Apr 13, 2020

sorex said:
I didn't look at UDG's file yet so what is it supposed to do?

LucaMs said:
If, on the other hand, that is exactly what he meant... it is a big nonsense!

This shows that being locked up for too long is bad for mental health ?

William Lancee · Apr 13, 2020

@sorex

Exactly what @Sandman says: It displays an exact copy of its own source code. If you then cut and paste it to another project, and run it, it will display another copy, etc.

William Lancee · Apr 13, 2020

@LucaMs

Like viruses, it does not do something useful (and much harm). It is simply ontologically evolved (or teleologically designed) to replicate itself.

LucaMs · Apr 13, 2020

I hoped the quiz was: how to make a sw (initially I had not noticed that it was B4J) which can run a new instance-copy of itself.

sorex · Apr 13, 2020

so the text area should show the entire source so that you can copy it in an empty project that it will run and show the same thing again?

William Lancee · Apr 13, 2020

@LucaMs
I believe that would take more than 66 lines of code, but feel free to try it

William Lancee · Apr 13, 2020

@sorex

I know it goes against all instincts, but Yes.

sorex · Apr 13, 2020

ok.

if it is

run project
copy source from text area to clipboard
paste source in new project
run
copy source from text area to clipboard *
clear project source window
paste clipboard in source window
run
repeat to *

then I got this working in 19 lines using a 1 line sub

William Lancee · Apr 13, 2020

Wow. I am impressed and love to see how you did it.

After a lot whittling away at my code, my total line count is still 47.

Maybe we can do a reveal at 3pm EST ( in 11 minutes).

sorex · Apr 13, 2020

sure no problem, I'll post it here when nobody goes lower

sorex · Apr 13, 2020

I'll pm you my project then you can see if I understood it right.

the difficulty is making it work right multiple times in a row.

William Lancee · Apr 13, 2020

@sorex

I tried it and after two iteration the source stabilizes and yields a 39 line module that does exactly what I was looking for.

(I was a little intimidated by the very long lines, but as the "Forged in Fire" guy says, it will Kill!)

Well done.

This is my best attempt.

B4X:

#Region Project Attributes
    #MainFormWidth: 800
    #MainFormHeight: 600
#End Region
Sub Process_Globals
    Private fx As JFX
    Public MainForm As Form
End Sub
Sub AppStart (Form1 As Form, Args() As String)
    MainForm = Form1
    Dim textArea1 As TextArea
    textArea1.Initialize("")
    MainForm.RootPane.AddNode(textArea1, 0, 0, MainForm.Width, MainForm.Height)
    MainForm.Title = "This is an exact replica of myself!"
    MainForm.Show
    Dim parts() As String = Array As String ("#Region Project Attributes~    #MainFormWidth: 800~    #MainFormHeight: 600~#End Region", _
    "~Sub Process_Globals~    Private fx As JFX~    Public MainForm As Form~End Sub", _
    "~Sub AppStart (Form1 As Form, Args() As String)~    MainForm = Form1~    Dim textArea1 As TextArea~    textArea1.Initialize('')", _
    "~    MainForm.RootPane.AddNode(textArea1, 0, 0, MainForm.Width, MainForm.Height)", _
    "~    MainForm.Title = 'This is an exact replica of myself!'~    MainForm.Show~    Dim parts() As String = Array As String (", _
    "~    Dim sb As StringBuilder~    sb.Initialize~    For j = 0 to 10~        sb.Append(parts(j))~    Next~    Dim v() As String = Regex.Split(Chr(126), sb.ToString)", _
    "~    sb.initialize~    For i = 0 To 15~        sb.Append(CRLF).Append(v(i).Replace(Chr(39), QUOTE))~    Next", _
    "~    sb.Append(CRLF).Append('    Dim parts() As String = Array As String (').Append(parts(0)).Append(', _')", _
    "~    For j = 1 To 10~        sb.Append(CRLF).Append(TAB).Append(QUOTE).Append(parts(j)).Append(QUOTE).Append(', _')~    Next", _
    "~    sb.Remove(sb.Length-3,sb.Length).Append(')')~    For i = 16 To v.length - 1~        sb.Append(CRLF).Append(v(i).Replace(Chr(39), QUOTE))~    Next", _
    "~    sb.Remove(0,1)~    textArea1.Text = sb.toString~End Sub")
    Dim sb As StringBuilder
    sb.initialize
    For j = 0 To 10
        sb.Append(parts(j))
    Next
    Dim v() As String = Regex.Split(Chr(126), sb.ToString)
    sb.Initialize
    For i = 0 To 15
        sb.Append(CRLF).Append(v(i).Replace(Chr(39), QUOTE))
    Next
    sb.Append(QUOTE).Append(parts(0)).Append(QUOTE).Append(", _")
    For j = 1 To 10
        sb.Append(CRLF).Append(TAB).Append(QUOTE).Append(parts(j)).Append(QUOTE).Append(", _")
    Next
    sb.Remove(sb.Length-3,sb.Length).Append(")")
    For i = 16 To v.Length - 1
        sb.Append(CRLF).Append(v(i).Replace(Chr(39), QUOTE))
    Next
    sb.Remove(0,1)
    textArea1.Text = sb.toString
End Sub

aeric · Apr 13, 2020

My attempt

B4X:

#Region Project Attributes
    #MainFormWidth: 600
    #MainFormHeight: 600
#End Region
Sub Process_Globals
    Private fx As JFX
    Public MainForm As Form
End Sub
Sub AppStart (Form1 As Form, Args() As String)
    Dim Q As Char = Chr(34)
    Dim Line() As String = Array As String( _
    "#Region Project Attributes", _
    "    #MainFormWidth: 600", _
    "    #MainFormHeight: 600", _
    "#End Region", _
    "Sub Process_Globals", _
    "    Private fx As JFX", _
    "    Public MainForm As Form", _
    "End Sub", _
    "Sub AppStart (Form1 As Form, Args() As String)", _
    "    Dim Q As Char = Chr(34)", _
    "    Dim Line() As String = Array As String( _", _
    "    ", _
    ")", _
    "    MainForm = Form1", _
    "    Dim textArea1 As TextArea: textArea1.Initialize(Chr(47) & Chr(47) & Chr(47) & Chr(47))", _
    "    MainForm.RootPane.AddNode(textArea1, 0, 0, MainForm.Width, MainForm.Height)", _
    "    MainForm.Title = ////This Is an exact replica of myself!////", _
    "    MainForm.Show", _
    "    'textArea1.Text =  ??              'In how many lines can you do this?   My best shot is 66 lines, including this preamble.", _
    "    Dim SB1 As StringBuilder : SB1.Initialize : Dim SB2 As StringBuilder : SB2.Initialize", _
    "    For i = 0 To 10", _
    "        SB1.Append(Line(i) & Chr(10))", _
    "    Next", _
    "    For i = 0 To Line.Length - 1", _
    "        SB1.Append(Line(11)).Append(Q).Append(Line(i)).Append(Q)", _
    "        If i < Line.Length - 1 Then SB1.Append(Chr(44)).Append(Chr(32)).Append(Chr(95)).Append(Chr(10))", _
    "    Next", _
    "    For i = 12 To Line.Length - 1", _
    "        SB2.Append(Line(i) & Chr(10))", _
    "    Next", _
    "    textArea1.Text = SB1.ToString.Replace(Chr(47)&Chr(47), Q) & SB2.ToString.Replace(Chr(47)&Chr(47)&Chr(47)&Chr(47), Q)", _
    "End Sub")
    MainForm = Form1
    Dim textArea1 As TextArea: textArea1.Initialize(Chr(47) & Chr(47) & Chr(47) & Chr(47))
    MainForm.RootPane.AddNode(textArea1, 0, 0, MainForm.Width, MainForm.Height)
    MainForm.Title = "This is an exact replica of myself!"
    MainForm.Show
    'textArea1.Text =  ??              'In how many lines can you do this?   My best shot is 66 lines, including this preamble.
    Dim SB1 As StringBuilder : SB1.Initialize : Dim SB2 As StringBuilder : SB2.Initialize
    For i = 0 To 10
        SB1.Append(Line(i)).Append(Chr(10))
    Next
    For i = 0 To Line.Length - 1
        SB1.Append(Line(11)).Append(Q).Append(Line(i)).Append(Q).ToString.Replace(Chr(47)&Chr(47), Q)
        If i < Line.Length - 1 Then SB1.Append(Chr(44)).Append(Chr(32)).Append(Chr(95)).Append(Chr(10))
    Next
    For i = 12 To Line.Length - 1
        SB2.Append(Line(i)).Append(Chr(10))
    Next
    textArea1.Text = SB1.ToString.Replace(Chr(47)&Chr(47), Q) & SB2.ToString.Replace(Chr(47)&Chr(47)&Chr(47)&Chr(47), Q)
End Sub

William Lancee · Apr 13, 2020

@aeric

I like it better than mine. You included the comment line with the "??"
You also avoided combining multiple statements on one line. It is much more readable.
It works!

Well done.

sorex · Apr 13, 2020

forgot to show mine

B4X:

#Region Project Attributes
    #MainFormWidth: 600
    #MainFormHeight: 600
#End Region
Sub Process_Globals
End Sub
Sub AppStart (Form1 As Form, Args() As String)
    Dim textArea1 As TextArea: textArea1.Initialize("")
    Form1.RootPane.AddNode(textArea1, 0, 0, Form1.Width, Form1.Height)
    Form1.Title = "This is an exact replica of myself!"
    Form1.Show
    textArea1.Text =  getSource($"#Region Project Attributes${CRLF}    #MainFormWidth: 600${CRLF}    #MainFormHeight: 600${CRLF}#End Region${CRLF}Sb Process_Globals${CRLF}End Sb${CRLF}Sb AppStart (Form1 As Form, Args() As String)${CRLF}    Dim textArea1 As TextArea: textArea1.Initialize("")${CRLF}    Form1.RootPane.AddNode(textArea1, 0, 0, Form1.Width, Form1.Height)${CRLF}    Form1.Title = 'This is an exact replica of myself!'${CRLF}    Form1.Show${CRLF}    textArea1.Text =  getSource(SC1)${CRLF}End Sb${CRLF}Sr getSource(source As String) as string${CRLF}    Return source.SubString2(0,source.IndexOf('S'&'r')).Replace('Sb','Sub').Replace(chr(0x27),QUOTE).replace('SC1','$' & QUOTE & source & QUOTE & '$') & source.SubString(source.IndexOf('S'&'r')).Replace('S'&'r','Sub').Replace(chr(0x27),QUOTE)${CRLF}End Sr"$)
End Sub
Sub getSource(source As String) As String
    Return source.SubString2(0,source.IndexOf("S"&"r")).Replace("Sb","Sub").Replace(Chr(0x27),QUOTE).replace("SC1","$" & QUOTE & source & QUOTE & "$") & source.SubString(source.Indexof("S"&"r")).Replace("S"&"r","Sub").Replace(Chr(0x27),QUOTE)
End Sub

you can cut 4 lines at the beginning as they are not really needed either.

some of the weirdness is to get around a possible bug with the smart strings as it seems to break when they contain sub or end sub in it.

William Lancee · Apr 14, 2020

@sorex

Yes, that's correct. Anything with those terms will fail.

aeric · Apr 14, 2020

aeric said:

My attempt

B4X:

#Region Project Attributes
    #MainFormWidth: 600
    #MainFormHeight: 600
#End Region
Sub Process_Globals
    Private fx As JFX
    Public MainForm As Form
End Sub
Sub AppStart (Form1 As Form, Args() As String)
    Dim Q As Char = Chr(34)
    Dim Line() As String = Array As String( _
    "#Region Project Attributes", _
    "    #MainFormWidth: 600", _
    "    #MainFormHeight: 600", _
    "#End Region", _
    "Sub Process_Globals", _
    "    Private fx As JFX", _
    "    Public MainForm As Form", _
    "End Sub", _
    "Sub AppStart (Form1 As Form, Args() As String)", _
    "    Dim Q As Char = Chr(34)", _
    "    Dim Line() As String = Array As String( _", _
    "    ", _
    ")", _
    "    MainForm = Form1", _
    "    Dim textArea1 As TextArea: textArea1.Initialize(Chr(47) & Chr(47) & Chr(47) & Chr(47))", _
    "    MainForm.RootPane.AddNode(textArea1, 0, 0, MainForm.Width, MainForm.Height)", _
    "    MainForm.Title = ////This Is an exact replica of myself!////", _
    "    MainForm.Show", _
    "    'textArea1.Text =  ??              'In how many lines can you do this?   My best shot is 66 lines, including this preamble.", _
    "    Dim SB1 As StringBuilder : SB1.Initialize : Dim SB2 As StringBuilder : SB2.Initialize", _
    "    For i = 0 To 10", _
    "        SB1.Append(Line(i) & Chr(10))", _
    "    Next", _
    "    For i = 0 To Line.Length - 1", _
    "        SB1.Append(Line(11)).Append(Q).Append(Line(i)).Append(Q)", _
    "        If i < Line.Length - 1 Then SB1.Append(Chr(44)).Append(Chr(32)).Append(Chr(95)).Append(Chr(10))", _
    "    Next", _
    "    For i = 12 To Line.Length - 1", _
    "        SB2.Append(Line(i) & Chr(10))", _
    "    Next", _
    "    textArea1.Text = SB1.ToString.Replace(Chr(47)&Chr(47), Q) & SB2.ToString.Replace(Chr(47)&Chr(47)&Chr(47)&Chr(47), Q)", _
    "End Sub")
    MainForm = Form1
    Dim textArea1 As TextArea: textArea1.Initialize(Chr(47) & Chr(47) & Chr(47) & Chr(47))
    MainForm.RootPane.AddNode(textArea1, 0, 0, MainForm.Width, MainForm.Height)
    MainForm.Title = "This is an exact replica of myself!"
    MainForm.Show
    'textArea1.Text =  ??              'In how many lines can you do this?   My best shot is 66 lines, including this preamble.
    Dim SB1 As StringBuilder : SB1.Initialize : Dim SB2 As StringBuilder : SB2.Initialize
    For i = 0 To 10
        SB1.Append(Line(i)).Append(Chr(10))
    Next
    For i = 0 To Line.Length - 1
        SB1.Append(Line(11)).Append(Q).Append(Line(i)).Append(Q).ToString.Replace(Chr(47)&Chr(47), Q)
        If i < Line.Length - 1 Then SB1.Append(Chr(44)).Append(Chr(32)).Append(Chr(95)).Append(Chr(10))
    Next
    For i = 12 To Line.Length - 1
        SB2.Append(Line(i)).Append(Chr(10))
    Next
    textArea1.Text = SB1.ToString.Replace(Chr(47)&Chr(47), Q) & SB2.ToString.Replace(Chr(47)&Chr(47)&Chr(47)&Chr(47), Q)
End Sub

I handled the double quote in inelegant way by using Replace.

Based on idea in Wikipedia example:

Quine (computing) - Wikipedia

en.wikipedia.org

aeric · Apr 14, 2020

sorex said:

forgot to show mine

B4X:

#Region Project Attributes
    #MainFormWidth: 600
    #MainFormHeight: 600
#End Region
Sub Process_Globals
End Sub
Sub AppStart (Form1 As Form, Args() As String)
    Dim textArea1 As TextArea: textArea1.Initialize("")
    Form1.RootPane.AddNode(textArea1, 0, 0, Form1.Width, Form1.Height)
    Form1.Title = "This is an exact replica of myself!"
    Form1.Show
    textArea1.Text =  getSource($"#Region Project Attributes${CRLF}    #MainFormWidth: 600${CRLF}    #MainFormHeight: 600${CRLF}#End Region${CRLF}Sb Process_Globals${CRLF}End Sb${CRLF}Sb AppStart (Form1 As Form, Args() As String)${CRLF}    Dim textArea1 As TextArea: textArea1.Initialize("")${CRLF}    Form1.RootPane.AddNode(textArea1, 0, 0, Form1.Width, Form1.Height)${CRLF}    Form1.Title = 'This is an exact replica of myself!'${CRLF}    Form1.Show${CRLF}    textArea1.Text =  getSource(SC1)${CRLF}End Sb${CRLF}Sr getSource(source As String) as string${CRLF}    Return source.SubString2(0,source.IndexOf('S'&'r')).Replace('Sb','Sub').Replace(chr(0x27),QUOTE).replace('SC1','$' & QUOTE & source & QUOTE & '$') & source.SubString(source.IndexOf('S'&'r')).Replace('S'&'r','Sub').Replace(chr(0x27),QUOTE)${CRLF}End Sr"$)
End Sub
Sub getSource(source As String) As String
    Return source.SubString2(0,source.IndexOf("S"&"r")).Replace("Sb","Sub").Replace(Chr(0x27),QUOTE).replace("SC1","$" & QUOTE & source & QUOTE & "$") & source.SubString(source.Indexof("S"&"r")).Replace("S"&"r","Sub").Replace(Chr(0x27),QUOTE)
End Sub

you can cut 4 lines at the beginning as they are not really needed either.

some of the weirdness is to get around a possible bug with the smart strings as it seems to break when they contain sub or end sub in it.

Impressive. Very few lines of code.

Challenge: A Self-Replicating App

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