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| 53 | <H2><A NAME="SECTION000510000000000000000"></A><A NAME="latex-syntax"></A> |
| 54 | <BR> |
| 55 | 4.1 Syntax |
| 56 | </H2> |
| 57 | |
| 58 | <P> |
| 59 | There are some things that an author of Python documentation needs |
| 60 | to know about <span class="LaTeX">LaTeX</span> syntax. |
| 61 | |
| 62 | <P> |
| 63 | A <i class="dfn">comment</i> is started by the ``percent'' character |
| 64 | ("<tt class="character">%</tt>") and continues through the end of the line and all |
| 65 | leading whitespace on the following line. This is a little |
| 66 | different from any programming language I know of, so an example |
| 67 | is in order: |
| 68 | |
| 69 | <P> |
| 70 | <div class="verbatim"><pre> |
| 71 | This is text.% comment |
| 72 | This is more text. % another comment |
| 73 | Still more text. |
| 74 | </pre></div> |
| 75 | |
| 76 | <P> |
| 77 | The first non-comment character following the first comment is the |
| 78 | letter "<tt class="character">T</tt>" on the second line; the leading whitespace on |
| 79 | that line is consumed as part of the first comment. This means |
| 80 | that there is no space between the first and second sentences, so |
| 81 | the period and letter "<tt class="character">T</tt>" will be directly adjacent in |
| 82 | the typeset document. |
| 83 | |
| 84 | <P> |
| 85 | Note also that though the first non-comment character after the |
| 86 | second comment is the letter "<tt class="character">S</tt>", there is whitespace |
| 87 | preceding the comment, so the two sentences are separated as |
| 88 | expected. |
| 89 | |
| 90 | <P> |
| 91 | A <i class="dfn">group</i> is an enclosure for a collection of text and |
| 92 | commands which encloses the formatting context and constrains the |
| 93 | scope of any changes to that context made by commands within the |
| 94 | group. Groups can be nested hierarchically. The formatting |
| 95 | context includes the font and the definition of additional macros |
| 96 | (or overrides of macros defined in outer groups). Syntactically, |
| 97 | groups are enclosed in braces: |
| 98 | |
| 99 | <P> |
| 100 | <div class="verbatim"><pre> |
| 101 | {text in a group} |
| 102 | </pre></div> |
| 103 | |
| 104 | <P> |
| 105 | An alternate syntax for a group using brackets, <code>[...]</code>, is |
| 106 | used by macros and environment constructors which take optional |
| 107 | parameters; brackets do not normally hold syntactic significance. |
| 108 | A degenerate group, containing only one atomic bit of content, |
| 109 | does not need to have an explicit group, unless it is required to |
| 110 | avoid ambiguity. Since Python tends toward the explicit, groups |
| 111 | are also made explicit in the documentation markup. |
| 112 | |
| 113 | <P> |
| 114 | Groups are used only sparingly in the Python documentation, except |
| 115 | for their use in marking parameters to macros and environments. |
| 116 | |
| 117 | <P> |
| 118 | A <i class="dfn">macro</i> is usually a simple construct which is identified by |
| 119 | name and can take some number of parameters. In normal <span class="LaTeX">LaTeX</span> |
| 120 | usage, one of these can be optional. The markup is introduced |
| 121 | using the backslash character ("<tt class="character">\</tt>"), and the name is |
| 122 | given by alphabetic characters (no digits, hyphens, or |
| 123 | underscores). Required parameters should be marked as a group, |
| 124 | and optional parameters should be marked using the alternate |
| 125 | syntax for a group. |
| 126 | |
| 127 | <P> |
| 128 | For example, a macro which takes a single parameter |
| 129 | would appear like this: |
| 130 | |
| 131 | <P> |
| 132 | <div class="verbatim"><pre> |
| 133 | \name{parameter} |
| 134 | </pre></div> |
| 135 | |
| 136 | <P> |
| 137 | A macro which takes an optional parameter would be typed like this |
| 138 | when the optional parameter is given: |
| 139 | |
| 140 | <P> |
| 141 | <div class="verbatim"><pre> |
| 142 | \name[optional] |
| 143 | </pre></div> |
| 144 | |
| 145 | <P> |
| 146 | If both optional and required parameters are to be required, it |
| 147 | looks like this: |
| 148 | |
| 149 | <P> |
| 150 | <div class="verbatim"><pre> |
| 151 | \name[optional]{required} |
| 152 | </pre></div> |
| 153 | |
| 154 | <P> |
| 155 | A macro name may be followed by a space or newline; a space |
| 156 | between the macro name and any parameters will be consumed, but |
| 157 | this usage is not practiced in the Python documentation. Such a |
| 158 | space is still consumed if there are no parameters to the macro, |
| 159 | in which case inserting an empty group (<code>{}</code>) or explicit |
| 160 | word space ("<tt class="samp">\ </tt>") immediately after the macro name helps to |
| 161 | avoid running the expansion of the macro into the following text. |
| 162 | Macros which take no parameters but which should not be followed |
| 163 | by a word space do not need special treatment if the following |
| 164 | character in the document source if not a name character (such as |
| 165 | punctuation). |
| 166 | |
| 167 | <P> |
| 168 | Each line of this example shows an appropriate way to write text |
| 169 | which includes a macro which takes no parameters: |
| 170 | |
| 171 | <P> |
| 172 | <div class="verbatim"><pre> |
| 173 | This \UNIX{} is followed by a space. |
| 174 | This \UNIX\ is also followed by a space. |
| 175 | \UNIX, followed by a comma, needs no additional markup. |
| 176 | </pre></div> |
| 177 | |
| 178 | <P> |
| 179 | An <i class="dfn">environment</i> is a larger construct than a macro, and can |
| 180 | be used for things with more content than would conveniently fit |
| 181 | in a macro parameter. They are primarily used when formatting |
| 182 | parameters need to be changed before and after a large chunk of |
| 183 | content, but the content itself needs to be highly flexible. Code |
| 184 | samples are presented using an environment, and descriptions of |
| 185 | functions, methods, and classes are also marked using environments. |
| 186 | |
| 187 | <P> |
| 188 | Since the content of an environment is free-form and can consist |
| 189 | of several paragraphs, they are actually marked using a pair of |
| 190 | macros: <tt class='macro'>\begin</tt> and <tt class='macro'>\end</tt>. These macros both take the |
| 191 | name of the environment as a parameter. An example is the |
| 192 | environment used to mark the abstract of a document: |
| 193 | |
| 194 | <P> |
| 195 | <div class="verbatim"><pre> |
| 196 | \begin{abstract} |
| 197 | This is the text of the abstract. It concisely explains what |
| 198 | information is found in the document. |
| 199 | |
| 200 | It can consist of multiple paragraphs. |
| 201 | \end{abstract} |
| 202 | </pre></div> |
| 203 | |
| 204 | <P> |
| 205 | An environment can also have required and optional parameters of |
| 206 | its own. These follow the parameter of the <tt class='macro'>\begin</tt> macro. |
| 207 | This example shows an environment which takes a single required |
| 208 | parameter: |
| 209 | |
| 210 | <P> |
| 211 | <div class="verbatim"><pre> |
| 212 | \begin{datadesc}{controlnames} |
| 213 | A 33-element string array that contains the \ASCII{} mnemonics for |
| 214 | the thirty-two \ASCII{} control characters from 0 (NUL) to 0x1f |
| 215 | (US), in order, plus the mnemonic \samp{SP} for the space character. |
| 216 | \end{datadesc} |
| 217 | </pre></div> |
| 218 | |
| 219 | <P> |
| 220 | There are a number of less-used marks in <span class="LaTeX">LaTeX</span> which are used |
| 221 | to enter characters which are not found in ASCII or which a |
| 222 | considered special, or <em>active</em> in <span class="TeX">TeX</span> or <span class="LaTeX">LaTeX</span>. Given |
| 223 | that these are often used adjacent to other characters, the markup |
| 224 | required to produce the proper character may need to be followed |
| 225 | by a space or an empty group, or the markup can be enclosed in a |
| 226 | group. Some which are found in Python documentation are: |
| 227 | |
| 228 | <P> |
| 229 | <div class="center"><table class="realtable"> |
| 230 | <thead> |
| 231 | <tr> |
| 232 | <th class="center">Character</th> |
| 233 | <th class="left" >Markup</th> |
| 234 | </tr> |
| 235 | </thead> |
| 236 | <tbody> |
| 237 | <tr><td class="center" valign="baseline">^</td> |
| 238 | <td class="left" ><code>\textasciicircum</code></td></tr> |
| 239 | <tr><td class="center" valign="baseline">~</td> |
| 240 | <td class="left" ><code>\textasciitilde</code></td></tr> |
| 241 | <tr><td class="center" valign="baseline">></td> |
| 242 | <td class="left" ><code>\textgreater</code></td></tr> |
| 243 | <tr><td class="center" valign="baseline"><</td> |
| 244 | <td class="left" ><code>\textless</code></td></tr> |
| 245 | <tr><td class="center" valign="baseline">ç</td> |
| 246 | <td class="left" ><code>\c c</code></td></tr> |
| 247 | <tr><td class="center" valign="baseline">ö</td> |
| 248 | <td class="left" ><code>\"o</code></td></tr> |
| 249 | <tr><td class="center" valign="baseline">ø</td> |
| 250 | <td class="left" ><code>\o</code></td></tr></tbody> |
| 251 | </table></div> |
| 252 | |
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