[Tex/LaTex] Refactoring TeX/LaTeX code

programming

Below is some shortened version of some code I wrote that can automatically format a number from decimal to scientific notation. I have been using it for some time now and have a few ideas how to combine it with some other work I have done into a small package for engineering calculations. However, looking back at what was a couple of hours of work, it definitely needs a good overhaul.

The code provides two major author commands \snotation{} and \enotation{} that return the input number in scientific or engineering notation.

I tend to go for readability of code rather than algorithmic elegance and find it easier to write the code than read through it later and change it. Neither loops nor if constructions are very reliable with TeX and I chose to "cut and paste code" rather than using these more error prone parts of TeX constructions.

Where can I find some information about re-factoring and polishing TeX code. Have you got a good strategy or tips and suggestions?

Here is the code as a working minimal (excludes the engineering part).

\documentclass{article}
\usepackage{fp,siunitx}
\begin{document}

\gdef\SetNumDecimals#1{\gdef\numdecimals{#1}}
\SetNumDecimals{10}
%% Helper routine for formatting numbers
%% first it round to 4 decimal numbers
%% then it clips the number so that if trailing
%% zeroes exist it removes them prints 16.01 and not 16.010000000
\newcommand\Clip[1]{\FPround\tmp{#1}{\numdecimals}\FPclip\tmp{\tmp}\tmp}%
\newcommand\Clipsmall[1]{\FPclip\tmp{#1}\tmp}%

\gdef\typeset#1#2{
  \def\clippednumber{\Clip{#1}}
  \def\powers##1{$##1 \times10^{#2}$}
  \powers{\clippednumber}
 }

\gdef\typesetsmall#1#2{
  \def\clippednumber{\Clipsmall{#1}}
  \def\powers##1{$##1 \times10^{#2}$}
  \powers{\clippednumber}
 }

\FPset\PowerOne{10}
\FPset\PowerTwo{100}
\FPset\PowerThree{1000}
\FPset\PowerFour{10000}
\FPset\PowerFive{100000}
\FPset\PowerSix{1000000}
\FPset\PowerSeven{10000000}
\FPset\PowerEight{100000000}
\FPset\PowerNine{1000000000}
\FPset\PowerTen{10000000000}
\FPset\PowerEleven{100000000000}
\FPset\PowerTwelve{1000000000000}
\FPset\PowerFifteen{1000000000000000}

\gdef\Epower{}
\gdef\result{}

\def\Powers#1{%
\FPset\Number{#1}
\FPifgt\Number\PowerTwo
   \FPdiv\temp{\Number}{\PowerTwo}
   \def\Epower{3}
   \FPset\result\temp
\fi
\FPifgt\Number\PowerThree
   \FPdiv\temp{\Number}{\PowerThree}
   \def\Epower{3}
   \global\let\result\temp
\fi

\FPifgt\Number\PowerFour
   \FPdiv\temp{\Number}{\PowerFour}
   \def\Epower{4}
   \global\let\result\temp
\fi

\FPifgt\Number\PowerFive
   \FPdiv\temp{\Number}{\PowerFive}
   \def\Epower{5}
   \global\let\result\temp
\fi

\FPifgt\Number\PowerSix
   \FPdiv\temp{\Number}{\PowerSix}
   \def\Epower{6}
   \global\let\result\temp
\fi

\FPifgt\Number\PowerSeven
   \FPdiv\temp{\Number}{\PowerSeven}
   \def\Epower{7}
   \global\let\result\temp
\fi

\FPifgt\Number\PowerEight
   \FPdiv\temp{\Number}{\PowerEight}
   \def\Epower{8}
   \global\let\result\temp
\fi

\FPifgt\Number\PowerNine
   \FPdiv\temp{\Number}{\PowerNine}
   \def\Epower{9}
   \global\let\result\temp
\fi

\FPifgt\Number\PowerTen
   \FPdiv\temp{\Number}{\PowerTen}
   \def\Epower{10}
   \global\let\result\temp
\fi

\FPifgt\Number\PowerEleven
   \FPdiv\temp{\Number}{\PowerEleven}
   \def\Epower{11}
   \global\let\result\temp
\fi

\FPifgt\Number\PowerTwelve
   \FPdiv\temp{\Number}{\PowerTwelve}
   \def\Epower{12}
   \global\let\result\temp
\fi
  \typeset{\result}{\Epower}
}

\FPset\one{1}

\def\piconums#1{%
\FPset\Number{#1}
\FPiflt\Number\one
   \FPmul\temp{\Number}{\PowerOne}
   \def\Epower{-1}
   \global\let\result\temp
\fi
\FPiflt\result\one
  \FPmul\temp{\Number}{\PowerTwo}
   \def\Epower{-2}
   \global\let\result\temp
 \else
\fi
\FPiflt\result\one
  \FPmul\temp{\Number}{\PowerThree}
   \def\Epower{-3}
   \global\let\result\temp
 \else
\fi
\FPiflt\result\one
  \FPmul\temp{\Number}{\PowerFour}
   \def\Epower{-4}
   \global\let\result\temp
\fi
\FPiflt\result\one
  \FPmul\temp{\Number}{\PowerFive}
   \def\Epower{-5}
   \global\let\result\temp
\fi
\FPiflt\result\one
  \FPmul\temp{\Number}{\PowerSix}
   \def\Epower{-6}
   \global\let\result\temp
\fi
\FPiflt\result\one
  \FPmul\temp{\Number}{\PowerSeven}
   \def\Epower{-7}
   \global\let\result\temp
\fi
\FPiflt\result\one
  \FPmul\temp{\Number}{\PowerEight}
   \def\Epower{-8}
   \global\let\result\temp
\fi
\FPiflt\result\one
  \FPmul\temp{\Number}{\PowerNine}
   \def\Epower{-9}
   \global\let\result\temp
\fi
\FPiflt\result\one
  \FPmul\temp{\Number}{\PowerTen}
   \def\Epower{-10}
   \global\let\result\temp
\fi
\FPiflt\result\one
  \FPmul\temp{\Number}{\PowerEleven}
   \def\Epower{-11}
   \global\let\result\temp
\fi
\FPiflt\result\one
  \FPmul\temp{\Number}{\PowerTwelve}
  \def\Epower{-12}
  \global\let\result\temp
\fi
\FPiflt\result\one
  \FPmul\temp{\Number}{\PowerFifteen}
  \def\Epower{-15}
  \global\let\result\temp
\fi

\typesetsmall{\result}{\Epower}
}

%% main routine
\def\snotation#1{
\FPset\Number{#1}
\FPifgt\Number\one
    \Powers{#1}
   \else
    \piconums{#1}
\fi}

\snotation{0.000000100326}

\snotation{1133009.1495978707}
\end{document}

Apologies for the length of the code.

Best Answer

I'm not sure there is a good guide to refactoring TeX code, but a few things I note from the above you might want to think about:

Making global assignments should always make you think 'is this really needed?'. While making things global is quite often easy, other approaches are sometimes better, for example
```
  \def\TempResult{Result}%
  \expandafter\endgroup
\expandafter\def\expandafter\RealResult\expandafter{\TempResult}%
```
Watch how you deal with \fi. Remember that unless you expand the end of the conditional then they continue to stack up, and can lead to runaway conditions or exhaustion of the stack. This is why approaches such as
```
  \expandafter\NextFunction
\fi
```
or
```
\if<something>
  \expandafter\@firstoftwo
\else
  \expandafter\@secondoftwo
\fi
  {True code}
  {False code}%
```
are very common (often the second is pre-packed, for example in etoolbox.
Unless you want maximum performance, I'd favour using more, well-named macros over fewer longer ones, and favour macros over primitives (so \@namedef rather than \expandafter\csname ...\endcsname, for example). (If you are really after maximum performance, then even additional \expandafters make a difference, but unless you are writing low-level kernel functions this should not be an issue!)

Using `style=A`

enter image description here

Using `style=B`

enter image description here

TeX Input File

\documentclass[dvipsnames,cmyk]{article}
\usepackage{listings,xcolor}

\lstset
{
    breaklines=true,
    tabsize=3,
    showstringspaces=false
}


\lstdefinestyle{Common}
{
    extendedchars=\true,
    language={[Visual]Basic},
    frame=single,
    %===========================================================
    framesep=3pt,%expand outward.
    framerule=0.4pt,%expand outward.
    xleftmargin=3.4pt,%make the frame fits in the text area. 
    xrightmargin=3.4pt,%make the frame fits in the text area.
    %=========================================================== 
    rulecolor=\color{Red}
}

\lstdefinestyle{A}
{
    style=Common,
    backgroundcolor=\color{Yellow!10},
    basicstyle=\scriptsize\color{Black}\ttfamily,
    keywordstyle=\color{Orange},
    identifierstyle=\color{Cyan},
    stringstyle=\color{Red},
    commentstyle=\color{Green}
}

\lstdefinestyle{B}
{
    style=Common,
    backgroundcolor=\color{Black},
    basicstyle=\scriptsize\color{White}\ttfamily,
    keywordstyle=\color{Orange},
    identifierstyle=\color{Cyan},
    stringstyle=\color{Red},
    commentstyle=\color{Green}
}

\begin{document}
\begin{lstlisting}[style=A]%please try style=B
Option Explicit

Sub Signal(strSignalfolge As String, Optional lngTakt As Long = 100)
'Prozedur erzeugt eine Serie von Warntönen.
'Die optionale Variable lngTakt gibt den Takt in Millisekunden vor (Standard: 100 ms)
'Das Muster kann über die String-Variable strSignalfolge beeinflusst werden:
' Stern (*)     -> 1 Warnton
' Ziffern 1..9  -> 1..9 Takte Pause
' Leerzeichen   -> 1 Sekunde Pause
' Minus (-)     -> 1.5 Sekunden Pause
    Dim i As Integer
    Dim b As String
    For i = 1 To Len(strSignalfolge)
        b = Mid(strSignalfolge, i, 1)
        Select Case b
            Case "*": beep
            Case 1 To 9: DELAY CInt(b) * lngTakt
            Case " ": DELAY 1000
            Case "-": DELAY 1500
        End Select
        DELAY lngTakt
    Next i

End Sub

Public Function strParse(Data As String, Trenn As String, Nr As Integer)
'Funktion trennt die Zeichenkette <Data>
    On Error Resume Next
    Dim MainData() As String, SplitData() As String
    MainData = Split(Data, Trenn)
    SplitData = Split(MainData(Nr - 1), Trenn)
    strParse = SplitData(0)
End Function


Public Sub ProtokollZeile(strData As String)
'Gibt eine Protokollzeile im Direktfenster aus: Datum, Uhrzeit und <strData>
    Debug.Print Now & " " & strData
End Sub

Sub NetSend(strmsg As String, Optional strEmpf As String = "imf3beck")
'Prozedur sendet die Kurznachricht <strMsg> über das Intranet an den Rechner <strEmpf>
    Dim a
    a = Shell("cmd.exe /c net send " & strEmpf & " " & strmsg, vbMinimizedFocus)
    MsgBox "(net send message)" & vbCr & strmsg
End Sub

Sub NetSendMessungBeendet(Optional strBem As String = "")
'Sendet über das Netzwerk eine Statusnachricht, dass die Messung beendet wurde und gibt diese
'Nachricht auch lokal als Warndialog aus
Dim strMsgText As String
strMsgText = (Format(Now, "hh:mm:ss") & " Messung beendet" & strBem)
NetSend (strMsgText)
End Sub

Public Function ZellBereichAdresse(strZellber As String) As String
Application.Volatile
ZellBereichAdresse = CStr(Range(strZellber).Address)
End Function
\end{lstlisting}
\end{document}

Notes:

It is better to import the VBA source code from within your TeX input file using \lstinputlisting[<options>]{filename.vb}. This way will make your TeX input file clean.
Try my style B by changing style=A to style=B.

[Tex/LaTex] Generating dumthe text programatically using TeX/LaTeX

The simplest way IMHO to do it is to use \foreach provided by the pgffor package. There is also the lower level \loop\ifnum\j<\k ... \repeat loop which could also be used. However, you need to wrap the inner loop in a group to mask the inner \repeat.

As Andrey already stated there are the open question about how to handle line breaks exactly. I simply use a \\ here, but you might need something else instead, dependent on the exact application. However, the principle usage of the loops is the same.

\documentclass{article}

\usepackage{pgffor}

\newcommand\dummytext[3]{%
    \foreach \n in {1,...,#3} {%
        \foreach \k in {1,...,#2} {%
            #1%
        }%
        \\
    }%
}

\begin{document}


\dummytext{HelloWorld}{5}{10}% 10 lines of 5x 'HelloWorld'

\end{document}

Best Answer

Related Solutions

[Tex/LaTex] How to typeset VBA code in LaTeX

Using style=A

Using style=B

TeX Input File

Notes:

[Tex/LaTex] Generating dumthe text programatically using TeX/LaTeX

Related Question

Using `style=A`

Using `style=B`