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86f6a31e | 1 | % \begin{meta-comment} <general public licence> |
2 | %% | |
3 | %% exercise package -- useful macros for setting exercises with answers | |
8bc5bdd2 | 4 | %% Copyright (c) 2001--2003 Mark Wooding |
86f6a31e | 5 | %% |
3d509049 | 6 | %% This file is part of the `mdwtools' LaTeX package collection. |
e8e9e5d8 | 7 | %% |
3d509049 MW |
8 | %% `mdwtools' is free software: you can redistribute it and/or modify it |
9 | %% under the terms of the GNU General Public License as published by the | |
10 | %% Free Software Foundation; either version 2 of the License, or (at your | |
11 | %% option) any later version. | |
12 | %% | |
13 | %% `mdwtools' is distributed in the hope that it will be useful, but | |
14 | %% WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | %% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | %% General Public License for more details. | |
e8e9e5d8 | 17 | %% |
86f6a31e | 18 | %% You should have received a copy of the GNU General Public License |
3d509049 | 19 | %% along with `mdwtools'. If not, write to the Free Software Foundation, |
86f6a31e | 20 | %% Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
3d509049 | 21 | %% |
86f6a31e | 22 | % \end{meta-comment} |
23 | % | |
24 | % \begin{meta-comment} <Package preambles> | |
25 | %<+package>\NeedsTeXFormat{LaTeX2e} | |
26 | %<+package>\ProvidesPackage{exercise} | |
af8af7eb | 27 | %<+package> [2020/09/06 1.14.0 Exercies with answers] |
86f6a31e | 28 | % \end{meta-comment} |
29 | % | |
db127fce | 30 | % \CheckSum{271} |
86f6a31e | 31 | %% \CharacterTable |
32 | %% {Upper-case \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z | |
33 | %% Lower-case \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z | |
34 | %% Digits \0\1\2\3\4\5\6\7\8\9 | |
35 | %% Exclamation \! Double quote \" Hash (number) \# | |
36 | %% Dollar \$ Percent \% Ampersand \& | |
37 | %% Acute accent \' Left paren \( Right paren \) | |
38 | %% Asterisk \* Plus \+ Comma \, | |
39 | %% Minus \- Point \. Solidus \/ | |
40 | %% Colon \: Semicolon \; Less than \< | |
41 | %% Equals \= Greater than \> Question mark \? | |
42 | %% Commercial at \@ Left bracket \[ Backslash \\ | |
43 | %% Right bracket \] Circumflex \^ Underscore \_ | |
44 | %% Grave accent \` Left brace \{ Vertical bar \| | |
45 | %% Right brace \} Tilde \~} | |
46 | %% | |
47 | % | |
48 | % \begin{meta-comment} | |
49 | % | |
50 | %<*driver> | |
51 | \input{mdwtools} | |
52 | \describespackage{exercise} | |
53 | \let\epsilon\varepsilon | |
db127fce | 54 | \errorcontextlines\maxdimen |
86f6a31e | 55 | \mdwdoc |
56 | %</driver> | |
57 | % | |
58 | % \end{meta-comment} | |
59 | % | |
60 | %^^A------------------------------------------------------------------------- | |
61 | % \section{User guide} | |
62 | % | |
63 | % The \package{exercise} package allows you to typeset exercises and keep the | |
64 | % answers together with the questions in your source (so they don't get | |
65 | % lost) but typeset them all together at the end of your document. | |
66 | % | |
67 | % \subsection{Exercises and answers} | |
68 | % | |
69 | % \DescribeEnv{exercise} | |
70 | % Exercises are typset in an \env{exercise} environment. This takes no | |
71 | % arguments. There's a counter for exercises, named |exercise|, and you can | |
72 | % cross-reference exercises in the usual way. | |
73 | % | |
74 | % \DescribeMacro\answer | |
75 | % If you want to include an answer for your exercise, just say |\answer| | |
76 | % followed by your answer. The rest of the text up to the end of the | |
77 | % \env{exercise} environment is considered to be the answer, and is stored | |
78 | % away until asked for. This material can contain anything you like. It | |
79 | % \emph{isn't} a moving argument. | |
80 | % | |
81 | % \begin{figure} | |
82 | %\begin{demo}[w]{The \env{exercise} environment} | |
83 | %\begin{exercise} | |
84 | %Show that if $F\colon \{0, 1\}^k \times \{0, 1\}^* \to \{0, 1\}^L$ | |
85 | %is a $(t, q + 1, \epsilon)$-secure PRF, then $F$~is also a | |
86 | %$(t, q, \epsilon + 2^{-L})$-secure MAC. | |
87 | %\answer | |
88 | %Let~$A$ be an adversary attacking~$F$ as a MAC. Consider the | |
89 | %adversary~$B$ \ldots | |
90 | %\end{exercise} | |
91 | %\end{demo} | |
92 | % \end{figure} | |
93 | % | |
db127fce | 94 | % \DescribeMacro\skipanswer |
95 | % The |\skipanswer| command is similar, but just skips over the answer rather | |
96 | % than writing it to the output file. It does nothing at all with counters | |
97 | % -- it's as if there was no answer given at all. | |
98 | % | |
99 | % It's OK to use commands like |\answer| and |\skipanswer| in your own | |
100 | % macros as long as they're the \emph{last} token. You can therefore say | |
101 | % something like | |
102 | %\begin{verbatim} | |
103 | %\newcommand{\evenanswer}{% | |
104 | % \ifthenelse% | |
105 | % {\isodd{\value{exercise}}}% | |
106 | % {\answer}% | |
107 | % {\skipanswer}% | |
108 | %} | |
109 | %\end{verbatim} | |
110 | % to get just the answers to the odd-numbered problems. (If you don't like | |
111 | % \package{ifthen} then you'll need to play with |\expandafter| for a bit.) | |
112 | % | |
86f6a31e | 113 | % \subsection{The answers file} |
114 | % | |
115 | % \DescribeMacro\answrite | |
116 | % Answers are accumulated into a file, to be read later. Additional material | |
117 | % can be added to the file using the |\answrite| macro, which just writes its | |
118 | % argument. Note that this is a \emph{moving} argument, so fragile commands | |
119 | % need |\protect|ing. | |
120 | % | |
121 | % \DescribeMacro\exctrcheck | |
122 | % It's common to divide up the answers by section. You can tell the package | |
123 | % to check a collection of counters and perform actions if they've changed | |
124 | % since last time, giving you a chance to write the correct decorations to | |
125 | % the answers file. This is done by saying | |
126 | % \syntax{"\\exctrcheck{"<counter>"}{"<action>"}"}. Then, each |\answer| | |
127 | % command checks to see if \<counter> has changed since last time, and if it | |
128 | % has, it does \<action>, For example, | |
129 | %\begin{verbatim} | |
130 | %\exctrcheck{section} | |
131 | % {\answrite{\protect\subsection*{Section \thesection}}} | |
132 | %\end{verbatim} | |
133 | % starts a new (unnumbered) subsection in the answers for each section in the | |
134 | % main document. | |
135 | % | |
136 | % \subsection{Style tweaks} | |
137 | % | |
138 | % The \env{exercise} environment is very simple, and can be easily rewritten | |
139 | % to fit in with your style preferences. If you like exercises to look like | |
140 | % theorems, the easiest thing to do is say something like | |
141 | %\begin{verbatim} | |
142 | %\newtheorem{doexercise}[exercise]{\exercisename} | |
143 | %\renewenvironment{exercise}{\exfix\doexercise}{\enddoexercise} | |
144 | %\end{verbatim} | |
145 | % This makes the environment use the existing exercise counter. If you don't | |
146 | % want that, say | |
147 | %\begin{verbatim} | |
148 | %\newtheorem{doexercise}[othercounter]{\exercisename} | |
149 | %\renewenvironment{exercise}{\exfix\doexercise}{\enddoexercise} | |
150 | %\let\theexercise\theothercounter | |
151 | %\end{verbatim} | |
152 | % and all will be well. | |
153 | % | |
154 | % \DescribeEnv{doanswer} | |
155 | % Answers are typeset in a \env{doanswer} environment, which is given one | |
156 | % argument: the exercise number (as set by |\theexercise|). This can be | |
157 | % modified to do whatever you like. | |
158 | % | |
159 | % \DescribeMacro\exfix | |
160 | % The |\exfix| is a convenient hook which is run both in the \env{exercise} | |
161 | % and \env{doanswer} environments by default. The current implementation | |
162 | % just skips a level of \env{enumerate} depth, which usually means that | |
163 | % \env{enumerate} lists will go (a), (b), (c), \ldots\ rather than 1, 2, 3, | |
164 | % \ldots | |
165 | % | |
166 | % \subsection{Lists in paragraphs} | |
167 | % | |
168 | % \DescribeEnv{parenum} | |
169 | % Answers to subparts tend to be compressed together into a single | |
170 | % paragraph. It's nice, when you do this, not to have to worry about losing | |
171 | % your numbering of subparts. The \env{parenum} environment provides an | |
172 | % enumerated list in a paragraph. So, for example, you can say something | |
173 | % like this. | |
174 | %\begin{demo}[w]{Example of \env{parenum}} | |
175 | %\begin{exercise} | |
176 | %A PRG $g\colon \{0, 1\}^k \to \{0, 1\}^L$ is \emph{trivial} if | |
177 | %$k \ge L$. | |
178 | %\begin{enumerate} | |
179 | %\item Show that trivial PRGs exist. | |
180 | %\item Show that a non-trivial $(t, \epsilon)$-secure PRG is a | |
181 | % $(t, \epsilon + 2^{k-L})$-secure one-way function. | |
182 | %\end{enumerate} | |
183 | %\answer | |
184 | %\begin{parenum} | |
185 | %\item The identity function is a trivial PRG: the real and random | |
186 | % games are identically distributed. | |
187 | %\item Let~$A$ be an adversary attempting to invert~$g$: then we | |
188 | % can construct a distinguisher~$B$ as follows \ldots | |
189 | %\end{parenum} | |
190 | %\end{exercise} | |
191 | %\end{demo} | |
192 | % | |
193 | % \subsection{And finally} | |
194 | % | |
195 | % \DescribeMacro\answers | |
196 | % In order to extract your answers, say |\answers|. | |
197 | %\begin{demo}[w]{The \texttt{\string\answers} command} | |
198 | %\section*{Answers} | |
199 | %\answers | |
200 | %\end{demo} | |
201 | % | |
db127fce | 202 | % The |\answers| command has an optional argument, which is the file to read |
203 | % in. This allows you to make `answer booklet' documents, by saying | |
204 | % something like | |
205 | %\begin{verbatim} | |
206 | %\answers[otherdoc] | |
207 | %\end{verbatim} | |
208 | % If you don't give a file extension, then |.ans| is appended automatically. | |
209 | % | |
86f6a31e | 210 | % \implementation |
e8e9e5d8 | 211 | % |
86f6a31e | 212 | % |
213 | %^^A------------------------------------------------------------------------- | |
214 | % \section{Implementation} | |
215 | % | |
216 | % \begin{macrocode} | |
217 | %<*package> | |
218 | % \end{macrocode} | |
219 | % | |
220 | % \subsection{Initialization} | |
221 | % | |
db127fce | 222 | % The \textsf{within} option is handled by the \package{mdwkey} package. |
86f6a31e | 223 | % |
224 | % \begin{macrocode} | |
db127fce | 225 | \RequirePackage{mdwkey} |
86f6a31e | 226 | % \end{macrocode} |
227 | % | |
228 | % \begin{macro}{\ex@within} | |
229 | % | |
230 | % When the \textsf{within} option is seen, we set a command |\ex@within| to | |
231 | % the correct code, to be executed later when we've made our minds up. | |
232 | % | |
233 | % \begin{macrocode} | |
234 | \let\ex@within\relax | |
db127fce | 235 | \mkdef{exercise:opts}{within}{% |
86f6a31e | 236 | \def\ex@within{% |
237 | \@addtoreset{exercise}{#1}% | |
238 | \toks@\expandafter{\csname the#1\expandafter\endcsname% | |
239 | \expandafter.\theexercise}% | |
240 | \edef\theexercise{\the\toks@}% | |
241 | }% | |
242 | } | |
243 | % \end{macrocode} | |
244 | % \end{macro} | |
245 | % | |
246 | % \begin{macro}{\ex@opts} | |
247 | % | |
db127fce | 248 | % The |\ex@opts| macro just runs the \package{mdwkey} kit to parse an option |
86f6a31e | 249 | % string. |
250 | % | |
251 | % \begin{macrocode} | |
db127fce | 252 | \def\ex@opts{\mkparse{exercise:opts}} |
86f6a31e | 253 | % \end{macrocode} |
254 | % \end{macro} | |
255 | % | |
256 | % Now do the options thing. | |
257 | % | |
258 | % \begin{macrocode} | |
259 | \DeclareOption*{\expandafter\ex@opts\expandafter{\CurrentOption}} | |
260 | \ProcessOptions* | |
261 | % \end{macrocode} | |
262 | % | |
263 | % Set up the |exercise| counter, and number it within some other sort of | |
264 | % counter as appropriate. | |
265 | % | |
266 | % \begin{macrocode} | |
267 | \newcounter{exercise}\ex@within | |
268 | % \end{macrocode} | |
269 | % | |
270 | % We also need the \package{sverb} package in order to do the delaying of the | |
271 | % answers. | |
272 | % | |
273 | % \begin{macrocode} | |
274 | \RequirePackage{sverb} | |
275 | % \end{macrocode} | |
276 | % | |
277 | % \subsection{Checking for counter changes} | |
278 | % | |
279 | % \begin{macro}{\ex@ctrcheck} | |
280 | % | |
281 | % The counter checking state is stored here. It's initially empty. | |
282 | % | |
283 | % \begin{macrocode} | |
284 | \def\ex@ctrcheck{} | |
285 | % \end{macrocode} | |
286 | % \end{macro} | |
287 | % | |
288 | % \begin{macro}{\exctrcheck} | |
289 | % | |
290 | % Adding a counter to the check list is relatively easy. We expand the | |
291 | % current list into a token register, add the new material to the end, and | |
292 | % put the list back in our macro using |\edef|. The `last' value of the | |
293 | % counter is set to |\relax|, to force out the change on the next |\answer|. | |
294 | % | |
295 | % \begin{macrocode} | |
296 | \def\exctrcheck#1#2{% | |
297 | \toks@\expandafter{\ex@ctrcheck\ex@ctrdo{#1}{#2}}% | |
298 | \edef\ex@ctrcheck{\the\toks@}% | |
299 | \global\expandafter\let\csname ex@ctrlast@#1\endcsname\relax% | |
300 | } | |
301 | % \end{macrocode} | |
302 | % \end{macro} | |
303 | % | |
304 | % \begin{macro}{\ex@ctrdo} | |
305 | % | |
306 | % Here we actually check to see whether a counter has changed and execute the | |
307 | % appropriate code. | |
308 | % | |
309 | % \begin{macrocode} | |
310 | \def\ex@ctrdo#1#2{% | |
311 | \edef\@tempa{\csname the#1\endcsname}% | |
312 | \expandafter\ifx\csname ex@ctrlast@#1\endcsname\@tempa\else% | |
313 | #2% | |
314 | \global\expandafter\let\csname ex@ctrlast@#1\endcsname\@tempa% | |
315 | \fi% | |
316 | } | |
317 | % \end{macrocode} | |
318 | % \end{macro} | |
319 | % | |
320 | % \subsection{The \env{exercise} environment} | |
321 | % | |
322 | % \begin{macro}{\exercisename} | |
323 | % | |
324 | % We store the string to print for each exercise in |\exercisename| as a | |
325 | % half-hearted attempt at internationalization. | |
326 | % | |
327 | % \begin{macrocode} | |
328 | \providecommand\exercisename{Exercise} | |
329 | % \end{macrocode} | |
330 | % \end{macro} | |
331 | % | |
332 | % \begin{macro}{\exfix} | |
333 | % | |
334 | % This is a dumping ground for style fixing common to both exercises and | |
335 | % answers. Here, we bump on the \env{enum} depth counter, so that it skips | |
336 | % labelling with digits. | |
337 | % | |
338 | % \begin{macrocode} | |
339 | \def\exfix{\advance\@enumdepth\@ne} | |
340 | % \end{macrocode} | |
341 | % \end{macro} | |
342 | % | |
343 | % \begin{environment}{exercise} | |
344 | % | |
345 | % This is pretty simple. The environment is list-based, with the number set | |
346 | % in bold in a label. | |
347 | % | |
348 | % \begin{macrocode} | |
349 | \def\exercise{% | |
350 | \refstepcounter{exercise}% | |
351 | \exfix% | |
352 | \trivlist\advance\itemindent\labelsep% | |
353 | \item[\textbf{\exercisename\ \theexercise}]% | |
354 | } | |
355 | \let\endexercise\endtrivlist | |
356 | % \end{macrocode} | |
357 | % \end{environment} | |
358 | % | |
359 | % \subsection{Answers} | |
360 | % | |
361 | % We need a file in which to store our answers. | |
362 | % | |
363 | % \begin{macrocode} | |
364 | \newwrite\ex@ansfile | |
365 | % \end{macrocode} | |
366 | % | |
367 | % \begin{macro}{\ex@ansfilename} | |
368 | % | |
369 | % In case anyone has a better idea for a filename than our default, we | |
370 | % provide a hook. | |
371 | % | |
372 | % \begin{macrocode} | |
373 | \def\ex@ansfilename{\jobname.ans} | |
374 | % \end{macrocode} | |
375 | % \end{macro} | |
376 | % | |
377 | % We open the file at the end of the preamble, to give the user a chance to | |
378 | % say |\nofiles|, or change |\ex@ansfilename|. | |
379 | % | |
380 | % \begin{macrocode} | |
381 | \AtBeginDocument{% | |
382 | \if@filesw% | |
383 | \immediate\openout\ex@ansfile=\ex@ansfilename\relax% | |
384 | \answrite\relax% | |
385 | \fi% | |
386 | } | |
387 | % \end{macrocode} | |
388 | % | |
389 | % \begin{macro}{\answrite} | |
390 | % | |
391 | % This writes stuff to the answers file. We make sure that it's | |
392 | % appropriately protected, so that you can insert section headings and so on. | |
393 | % | |
394 | % \begin{macrocode} | |
395 | \def\answrite#1{% | |
396 | \if@filesw% | |
397 | \begingroup% | |
398 | \let\protect\@unexpandable@protect% | |
399 | \immediate\write\ex@ansfile{#1}% | |
400 | \endgroup% | |
401 | \fi% | |
402 | } | |
403 | % \end{macrocode} | |
404 | % \end{macro} | |
405 | % | |
406 | % \begin{macro}{\answer} | |
407 | % | |
408 | % The |\answer| macro needs to read until the end of the enclosing | |
409 | % \env{exercise} environment (or whatever). | |
410 | % | |
411 | % \begin{macrocode} | |
412 | \def\answer{\sv@readenv\ex@answer} | |
413 | % \end{macrocode} | |
414 | % | |
415 | % Now for the main guts. | |
416 | % | |
417 | % \begin{macrocode} | |
418 | \def\ex@answer#1#2{% | |
419 | \begingroup% | |
420 | \@bsphack% | |
421 | % \end{macrocode} | |
422 | % | |
423 | % First of all, check to see whether any counters have changed. | |
424 | % | |
425 | % \begin{macrocode} | |
426 | \ex@ctrcheck% | |
427 | % \end{macrocode} | |
428 | % | |
429 | % Start a \env{doanswer} environment in the file. | |
430 | % | |
431 | % \begin{macrocode} | |
432 | \answrite{\noexpand\begin{doanswer}{\theexercise}}% | |
433 | % \end{macrocode} | |
434 | % | |
435 | % Set catcodes to be strange, and read lines one-at-a-time, writing them to | |
436 | % the file. When finished, continue at |\ex@endanswer|. | |
437 | % | |
438 | % \begin{macrocode} | |
439 | \let\do\@makeother\dospecials% | |
440 | \sv@safespc% | |
441 | \sv@read{#1}\answrite{\ex@endanswer#2}% | |
442 | } | |
443 | % \end{macrocode} | |
444 | % | |
445 | % When that's done, we wind up here. | |
446 | % | |
447 | % \begin{macrocode} | |
448 | \def\ex@endanswer{% | |
449 | \@esphack% | |
450 | \answrite{\noexpand\end{doanswer}}% | |
451 | \endgroup% | |
452 | } | |
453 | % \end{macrocode} | |
454 | % \end{macro} | |
455 | % | |
db127fce | 456 | % \begin{macro}{\skipanswer} |
457 | % | |
458 | % This is much simpler. | |
459 | % | |
460 | % \begin{macrocode} | |
461 | \let\skipanswer\ignore | |
462 | % \end{macrocode} | |
463 | % \end{macro} | |
464 | % | |
86f6a31e | 465 | % \begin{macro}{\answers} |
466 | % | |
467 | % The |\answers| macro closes the file, makes sure that future | |
468 | % \env{exercise}s with answers cause an error, and reads in the file. | |
469 | % | |
470 | % \begin{macrocode} | |
471 | \def\answers{% | |
db127fce | 472 | \@ifnextchar[{\answers@i\input}{\answers@i\@input[\ex@ansfilename]}% |
473 | } | |
474 | \def\answers@i#1[#2]{% | |
86f6a31e | 475 | \immediate\closeout\ex@ansfile% |
476 | \global\let\answrite\exerr@toolate% | |
db127fce | 477 | \ex@withext{#1}{#2}{ans}% |
478 | } | |
479 | \def\q@delim{\q@delim} | |
480 | \def\ex@withext#1#2#3{% | |
481 | \edef\next@##1{\noexpand\ex@ext@i{##1}{#2}{#3}#2.\noexpand\q@delim}% | |
482 | \next@{#1}% | |
483 | } | |
484 | \def\ex@ext@i#1#2#3#4.#5\q@delim{% | |
485 | \ifx\q@delim#5\q@delim\def\next@{#1{#2.#3}}% | |
486 | \else\def\next@{#1{#2}}\fi% | |
487 | \next@% | |
86f6a31e | 488 | } |
489 | % \end{macrocode} | |
490 | % \end{macro} | |
491 | % | |
492 | % \begin{environment}{doanswer} | |
493 | % | |
494 | % A very simple environment. We set the exercise number in bold and then | |
495 | % just write the text. | |
496 | % | |
497 | % \begin{macrocode} | |
498 | \def\doanswer#1{% | |
499 | \exfix% | |
500 | \trivlist\advance\itemindent\labelsep% | |
501 | \item[\textbf{#1}]% | |
502 | } | |
503 | \let\enddoanswer\endtrivlist | |
504 | % \end{macrocode} | |
505 | % \end{environment} | |
506 | % | |
507 | % \subsection{Lists inside paragraphs} | |
508 | % | |
509 | % \begin{environment}{parlist} | |
510 | % | |
511 | % The \env{parlist} environment is a trimmed-down version of a normal list. | |
512 | % We todge the |\item| command, make |\list| and |\trivlist| make errors, and | |
e8e9e5d8 | 513 | % do various normal list things. |
86f6a31e | 514 | % |
515 | % \begin{macrocode} | |
516 | \def\parlist#1#2{% | |
517 | \let\@trivlist\exerr@parlist% | |
518 | \def\@itemlabel{#1}% | |
519 | \let\makelabel\relax% | |
520 | \@nmbrlistfalse% | |
521 | #2% | |
522 | \let\item\pl@item% | |
523 | \ignorespaces% | |
524 | } | |
525 | % \end{macrocode} | |
526 | % \end{environment} | |
527 | % | |
528 | % \begin{macro}{\pl@item} | |
529 | % | |
530 | % This is the implementation of |\item| within a \env{parlist}. The main | |
531 | % interesting point is the game with boxes, which has the objective of | |
532 | % extracting the text of the item, together with any style changes set by | |
533 | % |\makelabel|, but without any stupid bits of glue, or |\llap| or anything | |
534 | % like that. | |
535 | % | |
536 | % \begin{macrocode} | |
537 | \def\pl@item{\@ifnextchar[\pl@item@i{\pl@item@i[\@itemlabel]}} | |
538 | \def\pl@item@i[#1]{% | |
539 | \if@nmbrlist\refstepcounter{\@listctr}\fi% | |
540 | \setbox\z@\hbox{\makelabel{\global\setbox\@ne\hbox{#1}}}% | |
541 | \ifvmode\leavevmode\else\unskip\hskip1em\fi\box\@ne~\ignorespaces% | |
542 | } | |
543 | % \end{macrocode} | |
544 | % \end{macro} | |
545 | % | |
546 | % \begin{macro}{\useparlist} | |
547 | % | |
548 | % We just set the \env{list} environment to use \env{parlist}. | |
549 | % | |
550 | % \begin{macrocode} | |
551 | \def\useparlist{\let\list\parlist\let\endlist\relax} | |
552 | % \end{macrocode} | |
553 | % \end{macro} | |
554 | % | |
555 | % \begin{environment}{parenum} | |
556 | % | |
557 | % Very simple, this. Note that we don't run |\endenumerate|, because that's | |
558 | % |\let| to |\endlist|. | |
559 | % | |
560 | % \begin{macrocode} | |
561 | \def\parenum{\useparlist\enumerate} | |
562 | \let\endparenum\endparlist | |
563 | % \end{macrocode} | |
564 | % \end{environment} | |
565 | % | |
566 | % \subsection{Errors} | |
567 | % | |
568 | % \begin{macrocode} | |
569 | \def\exerr@toolate{% | |
570 | \PackageError{exercise}{Too late now for \string\answrite}{% | |
571 | You can't write answers after you've read the file in. I've^^J% | |
572 | ignored the text you attempted to write. This is why answers^^J% | |
573 | go at the end of a book!% | |
574 | }% | |
575 | } | |
576 | \def\exerr@parlist{% | |
577 | \PackageError{exercise}{You can't nest a `list' inside a `parlist'.}{% | |
578 | I've found a `list' or `trivlist' environment nested inside^^J% | |
db127fce | 579 | a `parlist'. This isn't allowed. You're probably doomed now.% |
86f6a31e | 580 | }% |
581 | } | |
582 | %</package> | |
583 | % \end{macrocode} | |
584 | % | |
585 | % Done. | |
586 | % | |
587 | % \hfill Mark Wooding, \today | |
588 | % | |
589 | % \Finale | |
590 | % | |
591 | \endinput |