Sorry (again) for un-digging a (very) old topic.
If I may add something to the previous answer, there are (at least) two programs who were designed to do that (opensource, with a GUI). So, this answers the "other approach" part, not the "pure LaTeX" one.
Basically, it will go recursively through one specific folder to find your .tex files and all your exercises in them. You can then click on a file containing exercises and it will compile it on-the-fly to show you the exercises : add the ones you want to your final document and then export it (to a tex or a pdf).
- TeXoMaker (disclaimer: I am not the author ;))
This one works almost like the previous one except that you first have to create a database of exercises and only then can you use it.
In both softwares you have a "search" functionnality so you can use metadata if you want and, for example, display only difficult exercises.
At least in TeXamator you can add randomly selected exercises (maybe in TeXoMaker also, but I can't say for sure).
Hope this helps !
Since your question is about storing, maintaining and referencing a large set of exercises (potentially in the order of 10,000), I'm going to concentrate on that, so the style here is very basic.
It's possible to define conditionals using \newif
(or through commands provided by packages such as etoolbox
). For example:
\newif\ifsolutions
\newif\ifcomplete
These default to false, but can be switched on:
\solutionstrue
\completetrue
It's also useful to provide syntactic commands to mark the solution. For example:
\newcommand{\solutionname}{Solution}
\newcommand{\solution}{\par\textbf{\solutionname}:\par}
As has been mentioned in one of the other answers, it's also possible to use environments and the comment
package. For multilingual support, the caption hooks can be used to redefine \solutionname
as appropriate. For example:
\usepackage[USenglish]{babel}
\addto\captionsUSenglish{%
\renewcommand\solutionname{Solution}%
}
Now an exercise can be written using these commands. For example:
$y = \sin(2x)$
\ifsolutions
\solution
\ifcomplete
Intermediate steps, further details etc.
\fi
$y' = 2\cos(2x)$
\fi
Environments provide a more LaTeXy feel, but let's concentrate on storing and accessing the questions.
The simple method, which has already been suggested, is to put each question in a separate file and load it with \input
. For example, if this exercise is in the file exercises/calculus/easy/dsin.tex
then the following MWE works:
\documentclass{article}
\newif\ifsolutions
\newif\ifcomplete
\solutionstrue
\completetrue
\newcommand{\solutionname}{Solution}
\newcommand{\solution}{\par\textbf{\solutionname}:\par}
\begin{document}
\begin{enumerate}
\item \input{exercises/calculus/easy/dsin}
\end{enumerate}
\end{document}
This is a relatively generic method, which can easily be translated to other TeX formats. For example, the Plain TeX equivalent is:
\newif\ifsolutions
\newif\ifcomplete
\solutionstrue
\completetrue
\def\solutionname{Solution}
\long\def\solution{\par{\bf\solutionname}:\par}
\newcount\questionnum
\long\def\question{%
\par
\advance\questionnum by 1\relax
\number\questionnum.
}
\question \input exercises/calculus/easy/dsin
\bye
The problem is that, although this structure is fine for a small number of questions, it can become unmanageable for 10,000. I mentioned datatooltk
in the comments, which can read and write .dbtex
files (datatool
's internal format), but I don't recommend using this format directly. These files just contain LaTeX code that defines the internal registers and control sequences used by datatool
to store the required data. There's no compression and it takes up a huge amount of resources. The datatooltk
application works better as an intermediary that can pull filtered, shuffled or sorted data from external sources in a way that can easily be input in the document. (See the datatool
performance page that compares build times for large databases.)
There are switches, such as --shuffle
or --sort
, which instructs datatooltk
to shuffle or sort the data after it's been pulled from the data source. This uses Java, which is more efficient than TeX, but if the data is stored in a SQL database, it's even more efficient to include these steps in the actual --sql
switch. (Currently, datatooltk
is only configured for MySQL, but it may be possible to use something else if the necessary .jar
file can be added to the class path.)
SQL databases can be optimized to improve performance. Suppose you want to randomly select 20 questions from 500. How do you perform that selection in LaTeX? First you'd need to use the shell to find out all the available files (or have an index file that can be parsed). Then you need to shuffle the list. That will take a while to do with TeX. It's more efficient to do this with SQL. (See, for example, MySQL select 10 random rows from 600K rows fast.)
If you decide to use SQL, the next thing to consider is the table structure.
- You'll need a unique id field. With this you'll be able to specifically select certain questions rather than have a random selection. (An auto increment primary key is best.)
- A field containing the question. (Let's call it
Question
.)
- A field containing the brief answer. (Let's call it
Answer
.)
- A field containing the extended answer. (Let's call it
ExtendedAnswer
.)
- A field identifying the difficulty level. (Let's call it
Level
.) This could be an integer (1 = easy) or an enumeration (easy
, medium
, hard
).
- A field identifying the topic. (Let's call it
Topic
.) An enumeration is probably the simplest type (for example, calculus
, settheory
).
I'm not quite sure about the language. There are two approaches that I can think of: have fields for the other language (For example, QuestionPortuges
, AnswerPortuges
and ExtendedAnswerPortuges
) or have a separate entry for the question in a different language with an extra field for the language.
So the above exercise example, could have
Question
=> $y = \sin(2x)$
Answer
=> $y' = 2\cos(2x)$
ExtendedAnswer
=> Intermediate steps, further details etc. \[y' = 2\cos(2x)\]
Level
=> 1
Topic
=> calculus
Language
=> english
or ExtendedAnswerPortuges
=> Passos intermédios, etc. \[y' = 2\cos(2x)\]
Note that this doesn't include the syntactic command \solution
or the conditionals \ifsolutions
and \ifcomplete
, which makes it easier to arrange the various parts of the question and answer.
It may be that some exercises require a particular package (such as amsmath
or graphicx
), so perhaps there could also be a field for the required packages. For example Packages
=> graphicx,amsmath
.
Any images or verbatim text must be stored outside the database somewhere on the file system. They could be on TeX's path or the database table could have a field with a list of external resources or the question/answer could simply use the full path.
The datatooltk
call can be done before the LaTeX run or using the shell escape. There's also a datatooltk
rule for arara
users. Let's suppose, I use datatooltk
to pull a random selection of questions and save the results in a file called exercises.dbtex
. This can then be loaded in the document using:
\DTLloaddbtex{\exercisedb}{exercises.dbtex}
If the data includes the Packages
field, you can make sure all the required packages are loaded by adding the following to the preamble:
\DTLforeach*{\exercisedb}{\Packages=Packages}
{\DTLifnullorempty{\Packages}{}{\usepackage{\Packages}}}
In the main part of the document:
\begin{enumerate}
\DTLforeach*{\exercisedb}% data base
{\Question=Question,\Answer=Answer,\ExtendedAnswer=ExtendedAnswer}% assignment list
{%
\item \Question
\ifsolutions
\solution
\ifcomplete
\ExtendedAnswer
\else
\Answer
\fi
\fi
}
\end{enumerate}
Further reading: Using the datatool Package for Exams or Assignment Sheets
Best Answer
Good on you to look in the source code. Good on the package author to use good macro names that describe the intent. I guessed from your posted snippet that
\QuestionNB
might be the macro that typeset the question number. Searching the source file for that string found me:Excellent! We know
\QuestionNB
sets the arabic representation of the value theQuestion
counter, with period and space. So all you have to do is insertinto the preamble after
\usepackage{exercise}
and you'll get what you want.(View this in CoCalc)
The command
\theQuestion
is for setting the counter value in\ref
erences. So the line renewing it will take care of the situation described by Peutsch in the comments.