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| 55 | <H1><A NAME="SECTION0052700000000000000000"> |
| 56 | 3.27 <tt class="module">pprint</tt> -- |
| 57 | Data pretty printer</A> |
| 58 | </H1> |
| 59 | |
| 60 | <P> |
| 61 | <A NAME="module-pprint"></A> |
| 62 | |
| 63 | <P> |
| 64 | The <tt class="module">pprint</tt> module provides a capability to ``pretty-print'' |
| 65 | arbitrary Python data structures in a form which can be used as input |
| 66 | to the interpreter. If the formatted structures include objects which |
| 67 | are not fundamental Python types, the representation may not be |
| 68 | loadable. This may be the case if objects such as files, sockets, |
| 69 | classes, or instances are included, as well as many other builtin |
| 70 | objects which are not representable as Python constants. |
| 71 | |
| 72 | <P> |
| 73 | The formatted representation keeps objects on a single line if it can, |
| 74 | and breaks them onto multiple lines if they don't fit within the |
| 75 | allowed width. Construct <tt class="class">PrettyPrinter</tt> objects explicitly if |
| 76 | you need to adjust the width constraint. |
| 77 | |
| 78 | <P> |
| 79 | The <tt class="module">pprint</tt> module defines one class: |
| 80 | |
| 81 | <P> |
| 82 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 83 | <td><nobr><b><span class="typelabel">class</span> <tt id='l2h-762' xml:id='l2h-762' class="class">PrettyPrinter</tt></b>(</nobr></td> |
| 84 | <td><var>...</var>)</td></tr></table></dt> |
| 85 | <dd> |
| 86 | Construct a <tt class="class">PrettyPrinter</tt> instance. This constructor |
| 87 | understands several keyword parameters. An output stream may be set |
| 88 | using the <var>stream</var> keyword; the only method used on the stream |
| 89 | object is the file protocol's <tt class="method">write()</tt> method. If not |
| 90 | specified, the <tt class="class">PrettyPrinter</tt> adopts <code>sys.stdout</code>. Three |
| 91 | additional parameters may be used to control the formatted |
| 92 | representation. The keywords are <var>indent</var>, <var>depth</var>, and |
| 93 | <var>width</var>. The amount of indentation added for each recursive level |
| 94 | is specified by <var>indent</var>; the default is one. Other values can |
| 95 | cause output to look a little odd, but can make nesting easier to |
| 96 | spot. The number of levels which may be printed is controlled by |
| 97 | <var>depth</var>; if the data structure being printed is too deep, the next |
| 98 | contained level is replaced by "<tt class="samp">...</tt>". By default, there is no |
| 99 | constraint on the depth of the objects being formatted. The desired |
| 100 | output width is constrained using the <var>width</var> parameter; the |
| 101 | default is eighty characters. If a structure cannot be formatted |
| 102 | within the constrained width, a best effort will be made. |
| 103 | |
| 104 | <P> |
| 105 | <div class="verbatim"><pre> |
| 106 | >>> import pprint, sys |
| 107 | >>> stuff = sys.path[:] |
| 108 | >>> stuff.insert(0, stuff[:]) |
| 109 | >>> pp = pprint.PrettyPrinter(indent=4) |
| 110 | >>> pp.pprint(stuff) |
| 111 | [ [ '', |
| 112 | '/usr/local/lib/python1.5', |
| 113 | '/usr/local/lib/python1.5/test', |
| 114 | '/usr/local/lib/python1.5/sunos5', |
| 115 | '/usr/local/lib/python1.5/sharedmodules', |
| 116 | '/usr/local/lib/python1.5/tkinter'], |
| 117 | '', |
| 118 | '/usr/local/lib/python1.5', |
| 119 | '/usr/local/lib/python1.5/test', |
| 120 | '/usr/local/lib/python1.5/sunos5', |
| 121 | '/usr/local/lib/python1.5/sharedmodules', |
| 122 | '/usr/local/lib/python1.5/tkinter'] |
| 123 | >>> |
| 124 | >>> import parser |
| 125 | >>> tup = parser.ast2tuple( |
| 126 | ... parser.suite(open('pprint.py').read()))[1][1][1] |
| 127 | >>> pp = pprint.PrettyPrinter(depth=6) |
| 128 | >>> pp.pprint(tup) |
| 129 | (266, (267, (307, (287, (288, (...)))))) |
| 130 | </pre></div> |
| 131 | </dl> |
| 132 | |
| 133 | <P> |
| 134 | The <tt class="class">PrettyPrinter</tt> class supports several derivative functions: |
| 135 | |
| 136 | <P> |
| 137 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 138 | <td><nobr><b><tt id='l2h-763' xml:id='l2h-763' class="function">pformat</tt></b>(</nobr></td> |
| 139 | <td><var>object</var><big>[</big><var>, indent</var><big>[</big><var>, |
| 140 | width</var><big>[</big><var>, depth</var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var>)</td></tr></table></dt> |
| 141 | <dd> |
| 142 | Return the formatted representation of <var>object</var> as a string. <var>indent</var>, |
| 143 | <var>width</var> and <var>depth</var> will be passed to the <tt class="class">PrettyPrinter</tt> |
| 144 | constructor as formatting parameters. |
| 145 | |
| 146 | <span class="versionnote">Changed in version 2.4: |
| 147 | The parameters <var>indent</var>, <var>width</var> and <var>depth</var> |
| 148 | were added.</span> |
| 149 | |
| 150 | </dl> |
| 151 | |
| 152 | <P> |
| 153 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 154 | <td><nobr><b><tt id='l2h-764' xml:id='l2h-764' class="function">pprint</tt></b>(</nobr></td> |
| 155 | <td><var>object</var><big>[</big><var>, stream</var><big>[</big><var>, |
| 156 | indent</var><big>[</big><var>, width</var><big>[</big><var>, depth</var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var>)</td></tr></table></dt> |
| 157 | <dd> |
| 158 | Prints the formatted representation of <var>object</var> on <var>stream</var>, |
| 159 | followed by a newline. If <var>stream</var> is omitted, <code>sys.stdout</code> |
| 160 | is used. This may be used in the interactive interpreter instead of a |
| 161 | <tt class="keyword">print</tt> statement for inspecting values. <var>indent</var>, |
| 162 | <var>width</var> and <var>depth</var> will be passed to the <tt class="class">PrettyPrinter</tt> |
| 163 | constructor as formatting parameters. |
| 164 | |
| 165 | <P> |
| 166 | <div class="verbatim"><pre> |
| 167 | >>> stuff = sys.path[:] |
| 168 | >>> stuff.insert(0, stuff) |
| 169 | >>> pprint.pprint(stuff) |
| 170 | [<Recursion on list with id=869440>, |
| 171 | '', |
| 172 | '/usr/local/lib/python1.5', |
| 173 | '/usr/local/lib/python1.5/test', |
| 174 | '/usr/local/lib/python1.5/sunos5', |
| 175 | '/usr/local/lib/python1.5/sharedmodules', |
| 176 | '/usr/local/lib/python1.5/tkinter'] |
| 177 | </pre></div> |
| 178 | |
| 179 | <span class="versionnote">Changed in version 2.4: |
| 180 | The parameters <var>indent</var>, <var>width</var> and <var>depth</var> |
| 181 | were added.</span> |
| 182 | |
| 183 | </dl> |
| 184 | |
| 185 | <P> |
| 186 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 187 | <td><nobr><b><tt id='l2h-765' xml:id='l2h-765' class="function">isreadable</tt></b>(</nobr></td> |
| 188 | <td><var>object</var>)</td></tr></table></dt> |
| 189 | <dd> |
| 190 | Determine if the formatted representation of <var>object</var> is |
| 191 | ``readable,'' or can be used to reconstruct the value using |
| 192 | <tt class="function">eval()</tt><a id='l2h-766' xml:id='l2h-766'></a>. This always returns false for |
| 193 | recursive objects. |
| 194 | |
| 195 | <P> |
| 196 | <div class="verbatim"><pre> |
| 197 | >>> pprint.isreadable(stuff) |
| 198 | False |
| 199 | </pre></div> |
| 200 | </dl> |
| 201 | |
| 202 | <P> |
| 203 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 204 | <td><nobr><b><tt id='l2h-767' xml:id='l2h-767' class="function">isrecursive</tt></b>(</nobr></td> |
| 205 | <td><var>object</var>)</td></tr></table></dt> |
| 206 | <dd> |
| 207 | Determine if <var>object</var> requires a recursive representation. |
| 208 | </dl> |
| 209 | |
| 210 | <P> |
| 211 | One more support function is also defined: |
| 212 | |
| 213 | <P> |
| 214 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 215 | <td><nobr><b><tt id='l2h-768' xml:id='l2h-768' class="function">saferepr</tt></b>(</nobr></td> |
| 216 | <td><var>object</var>)</td></tr></table></dt> |
| 217 | <dd> |
| 218 | Return a string representation of <var>object</var>, protected against |
| 219 | recursive data structures. If the representation of <var>object</var> |
| 220 | exposes a recursive entry, the recursive reference will be represented |
| 221 | as "<tt class="samp"><Recursion on <var>typename</var> with id=<var>number</var>></tt>". The |
| 222 | representation is not otherwise formatted. |
| 223 | </dl> |
| 224 | |
| 225 | <P> |
| 226 | <div class="verbatim"><pre> |
| 227 | >>> pprint.saferepr(stuff) |
| 228 | "[<Recursion on list with id=682968>, '', '/usr/local/lib/python1.5', '/usr/loca |
| 229 | l/lib/python1.5/test', '/usr/local/lib/python1.5/sunos5', '/usr/local/lib/python |
| 230 | 1.5/sharedmodules', '/usr/local/lib/python1.5/tkinter']" |
| 231 | </pre></div> |
| 232 | |
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