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| 57 | 6.21.4.6 Callback example 3: check option order (generalized) |
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| 59 | |
| 60 | <P> |
| 61 | If you want to re-use this callback for several similar options (set a |
| 62 | flag, but blow up if <code>"-b"</code> has already been seen), it needs a bit of |
| 63 | work: the error message and the flag that it sets must be |
| 64 | generalized. |
| 65 | <div class="verbatim"><pre> |
| 66 | def check_order(option, opt_str, value, parser): |
| 67 | if parser.values.b: |
| 68 | raise OptionValueError("can't use %s after -b" % opt_str) |
| 69 | setattr(parser.values, option.dest, 1) |
| 70 | [...] |
| 71 | parser.add_option("-a", action="callback", callback=check_order, dest='a') |
| 72 | parser.add_option("-b", action="store_true", dest="b") |
| 73 | parser.add_option("-c", action="callback", callback=check_order, dest='c') |
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