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| 55 | <H3><A NAME="SECTION007232000000000000000"></A><A NAME="doctest-finding-examples"></A> |
| 56 | <BR> |
| 57 | 5.2.3.2 How are Docstring Examples |
| 58 | Recognized? |
| 59 | </H3> |
| 60 | |
| 61 | <P> |
| 62 | In most cases a copy-and-paste of an interactive console session works |
| 63 | fine, but doctest isn't trying to do an exact emulation of any specific |
| 64 | Python shell. All hard tab characters are expanded to spaces, using |
| 65 | 8-column tab stops. If you don't believe tabs should mean that, too |
| 66 | bad: don't use hard tabs, or write your own <tt class="class">DocTestParser</tt> |
| 67 | class. |
| 68 | |
| 69 | <P> |
| 70 | |
| 71 | <span class="versionnote">Changed in version 2.4: |
| 72 | Expanding tabs to spaces is new; previous versions |
| 73 | tried to preserve hard tabs, with confusing results.</span> |
| 74 | |
| 75 | <P> |
| 76 | <div class="verbatim"><pre> |
| 77 | >>> # comments are ignored |
| 78 | >>> x = 12 |
| 79 | >>> x |
| 80 | 12 |
| 81 | >>> if x == 13: |
| 82 | ... print "yes" |
| 83 | ... else: |
| 84 | ... print "no" |
| 85 | ... print "NO" |
| 86 | ... print "NO!!!" |
| 87 | ... |
| 88 | no |
| 89 | NO |
| 90 | NO!!! |
| 91 | >>> |
| 92 | </pre></div> |
| 93 | |
| 94 | <P> |
| 95 | Any expected output must immediately follow the final |
| 96 | <code>'><code>></code>> '</code> or <code>'... '</code> line containing the code, and |
| 97 | the expected output (if any) extends to the next <code>'><code>></code>> '</code> |
| 98 | or all-whitespace line. |
| 99 | |
| 100 | <P> |
| 101 | The fine print: |
| 102 | |
| 103 | <P> |
| 104 | |
| 105 | <UL> |
| 106 | <LI>Expected output cannot contain an all-whitespace line, since such a |
| 107 | line is taken to signal the end of expected output. If expected |
| 108 | output does contain a blank line, put <code><BLANKLINE></code> in your |
| 109 | doctest example each place a blank line is expected. |
| 110 | |
| 111 | <span class="versionnote">Changed in version 2.4: |
| 112 | <code><BLANKLINE></code> was added; there was no way to |
| 113 | use expected output containing empty lines in |
| 114 | previous versions.</span> |
| 115 | |
| 116 | <P> |
| 117 | </LI> |
| 118 | <LI>Output to stdout is captured, but not output to stderr (exception |
| 119 | tracebacks are captured via a different means). |
| 120 | |
| 121 | <P> |
| 122 | </LI> |
| 123 | <LI>If you continue a line via backslashing in an interactive session, |
| 124 | or for any other reason use a backslash, you should use a raw |
| 125 | docstring, which will preserve your backslashes exactly as you type |
| 126 | them: |
| 127 | |
| 128 | <P> |
| 129 | <div class="verbatim"><pre> |
| 130 | >>> def f(x): |
| 131 | ... r'''Backslashes in a raw docstring: m\n''' |
| 132 | >>> print f.__doc__ |
| 133 | Backslashes in a raw docstring: m\n |
| 134 | </pre></div> |
| 135 | |
| 136 | <P> |
| 137 | Otherwise, the backslash will be interpreted as part of the string. |
| 138 | For example, the "\" above would be interpreted as a |
| 139 | newline character. Alternatively, you can double each backslash in the |
| 140 | doctest version (and not use a raw string): |
| 141 | |
| 142 | <P> |
| 143 | <div class="verbatim"><pre> |
| 144 | >>> def f(x): |
| 145 | ... '''Backslashes in a raw docstring: m\\n''' |
| 146 | >>> print f.__doc__ |
| 147 | Backslashes in a raw docstring: m\n |
| 148 | </pre></div> |
| 149 | |
| 150 | <P> |
| 151 | </LI> |
| 152 | <LI>The starting column doesn't matter: |
| 153 | |
| 154 | <P> |
| 155 | <div class="verbatim"><pre> |
| 156 | >>> assert "Easy!" |
| 157 | >>> import math |
| 158 | >>> math.floor(1.9) |
| 159 | 1.0 |
| 160 | </pre></div> |
| 161 | |
| 162 | <P> |
| 163 | and as many leading whitespace characters are stripped from the |
| 164 | expected output as appeared in the initial <code>'><code>></code>> '</code> line |
| 165 | that started the example. |
| 166 | </LI> |
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