Text Formatting ⇒ Making Sense of Code

[LaTexLearner]

This is a follow-up to a thread on using the exsheets package to embed examples and solutions.

http://tex.stackexchange.com/questions/ ... orksheets/

I am trying to make sense of the first part of the code (non-TikZ stuff) and have preceded my comments in the code with %%%.

Code: Select all

%%%  MY COMMENTS

\documentclass{article}
\usepackage{exsheets,amsmath}

\makeatletter
% a color for answers
\colorlet{answercolor}{orange}

%%% I did not understand the whole "true/false input stream" explanation in the exsheets manual.
\newcommand\answer[1]{\PrintSolutionsTF{#1}{\phantom{#1}}}

%%%  Defines a new length called "\answerspaces" and sets them to be 2cm long.
\newlength\answerspace
\setlength\answerspace{2cm}

%%% If math mode something happens and if not in math mode something else happens? 
\newcommand\answerline[1]{%
  \ifmmode
    \answerline@math{#1}%
  \else
    \answerline@text{#1}%
  \fi
}

%%% No idea what's happening from here until the printing options stuff.
\newcommand*\answerline@text[1]{%
  \underline{\makebox[\answerspace][c]{\answer{\color{answercolor}#1}}}%
}
\newcommand\answerline@math[1]{\mathpalette\answer@line@math{#1}}
\newcommand\answer@line@math[2]{\answerline@text{$#1#2$}}
\makeatother


% uncomment to get answers printed:
% \SetupExSheets{solution/print=true}

\begin{document}

\section*{Find the unknown.}
\begin{question}
  \( 3 + \answerline{1} = 4 \)
\end{question}
\begin{question}
  \( 4 =  \answerline{14} -10 \)
\end{question}

\end{document}

[LaTexLearner]

Also, is there any way to set the answer space so that the default length is, say, 2cm, but there is an optional argument to make it longer?

[cgnieder]

Code: Select all

%%% I did not understand the whole "true/false input stream" explanation in the exsheets manual.
\newcommand\answer[1]{\PrintSolutionsTF{#1}{\phantom{#1}}}

The input stream is everything TeX sees for typesetting. It's a term from the TeX book I believe. The idea is easy: when the option solution/print=true is active the first argument of \PrintSolutionsTF is printed otherwise the second.

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%%%  Defines a new length called "\answerspaces" and sets them to be 2cm long.
\newlength\answerspace
\setlength\answerspace{2cm}

yes (except for the trailing s)

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%%% If math mode something happens and if not in math mode something else happens? 
\newcommand\answerline[1]{%
  \ifmmode
    \answerline@math{#1}%
  \else
    \answerline@text{#1}%
  \fi
}

yes

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%%% No idea what's happening from here until the printing options stuff.
\newcommand*\answerline@text[1]{%
  \underline{\makebox[\answerspace][c]{\answer{\color{answercolor}#1}}}%
}

Something is underlined \underline{...}. Within a box ob length \answerspace is placed and the contents are centered: \makebox[\answerspace][c]{...}. This ensures we get a line with length \answerspace. In this box we put \answer{\color{answercolor}#1}. This is the macro we defined earlier that will only print something when solution/print=true but then will print it in orange.

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\newcommand\answerline@math[1]{\mathpalette\answer@line@math{#1}}
\newcommand\answer@line@math[2]{\answerline@text{$#1#2$}}
\makeatother

\mathpalette\foo{x} is the same as this:

Code: Select all

\mathchoice
  {\foo{\displaystyle}{x}}
  {\foo{\textstyle}{x}}
  {\foo{\scriptstyle}{x}}
  {\foo{\scriptscriptstyle}{x}}

With this it is possible to use \answerline in the different places in math (displayed equations, inline math, superscripts,…) and still get the correct size. If we did instead

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\newcommand\answer@line@math[1]{\answerline@text{$#1$}}

the contents always would be printed as text style.

Regards

[cgnieder]

Also, is there any way to set the answer space so that the default length is, say, 2cm, but there is an optional argument to make it longer?

One possibility: change the definition of \answerline like this:

Code: Select all

\newcommand\answerline[2][\answerspace]{%
  \begingroup
    \ifdim#1=\answerspace
    \else
      \setlength\answerspace{#1}%
    \fi
    \ifmmode
      \answerline@math{#2}%
    \else
      \answerline@text{#2}%
    \fi
  \endgroup
}

[LaTexLearner]

Let's see if I can take ~one of these at a time.

Code: Select all

%%% I did not understand the whole "true/false input stream" explanation in the exsheets manual.
\newcommand\answer[1]{\PrintSolutionsTF{#1}{\phantom{#1}}}

The input stream is everything TeX sees for typesetting. It's a term from the TeX book I believe. The idea is easy: when the option solution/print=true is active the first argument of \PrintSolutionsTF is printed otherwise the second.

I see.

1. Where is the the option solution/print=true set and how do you set it?
2. Does \phantom{#1} mean "blank"?

[LaTexLearner]

Code: Select all

%%% If math mode something happens and if not in math mode something else happens? 
\newcommand\answerline[1]{%
  \ifmmode
    \answerline@math{#1}%
  \else
    \answerline@text{#1}%
  \fi
}

yes

1. If the text after \answerline is in math mode then X happens. What is X? And if if it is not in math mode, then Y happens. What's Y?
2. What do the @math and @text actually mean? (I'll postpone asking questions about the last section of the code until I understand this part.)
3. What does \fi mean? I Googled it but could not make sense of it.

[LaTexLearner]

Code: Select all

%%% No idea what's happening from here until the printing options stuff.
\newcommand*\answerline@text[1]{%
  \underline{\makebox[\answerspace][c]{\answer{\color{answercolor}#1}}}%
}

Something is underlined \underline{...}. Within a box ob length \answerspace is placed and the contents are centered: \makebox[\answerspace][c]{...}. This ensures we get a line with length \answerspace. In this box we put \answer{\color{answercolor}#1}. This is the macro we defined earlier that will only print something when solution/print=true but then will print it in orange.

Got it. Good explanation!

My only question: What if I didn't want the answer space to be a 2cm line? E.g. What if I wanted, say, 3cm of blank space on the workbook pages for students to write in and for my solutions to appear in those 3cm?

[cgnieder]

1. Where is the the option solution/print=true set and how do you set it?
2. Does \phantom{#1} mean "blank"?

1. Look at the code in your first post on the top:

   Code: Select all

   \SetupExSheets{solution/print=true}

   It is an option of exsheets and described in the manual.
2. \phantom{...} typesets the space that ... would need.

[cgnieder]

My only question: What if I didn't want the answer space to be a 2cm line? E.g. What if I wanted, say, 3cm of blank space on the workbook pages for students to write in and for my solutions to appear in those 3cm?

Either change the default in

Code: Select all

\setlength\answerspace{2cm}

to another value or use the adapted proposal where \answerline got an option for other lengths than the default.

[Johannes_B]

Let's see if I can take ~one of these at a time.

Code: Select all

%%% I did not understand the whole "true/false input stream" explanation in the exsheets manual.
\newcommand\answer[1]{\PrintSolutionsTF{#1}{\phantom{#1}}}

The input stream is everything TeX sees for typesetting. It's a term from the TeX book I believe. The idea is easy: when the option solution/print=true is active the first argument of \PrintSolutionsTF is printed otherwise the second.

I see.

1. Where is the the option solution/print=true set and how do you set it?
2. Does \phantom{#1} mean "blank"?

1. Look at your initial post, it is commented out, there is even an explanation.

2. Yes, a phantom reserves the space but does not typeset. something mysterious is going on, like a phantom you cannot see.