1 | # (c) 2005 Ian Bicking and contributors; written for Paste (http://pythonpaste.org) |
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2 | # Licensed under the MIT license: http://www.opensource.org/licenses/mit-license.php |
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3 | """ |
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4 | Fixes the vague error message that you get when calling a function |
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5 | with the wrong arguments. |
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6 | """ |
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7 | import inspect |
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8 | import sys |
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9 | |
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10 | def fix_type_error(exc_info, callable, varargs, kwargs): |
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11 | """ |
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12 | Given an exception, this will test if the exception was due to a |
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13 | signature error, and annotate the error with better information if |
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14 | so. |
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15 | |
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16 | Usage:: |
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17 | |
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18 | try: |
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19 | val = callable(*args, **kw) |
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20 | except TypeError: |
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21 | exc_info = fix_type_error(None, callable, args, kw) |
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22 | raise exc_info[0], exc_info[1], exc_info[2] |
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23 | """ |
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24 | if exc_info is None: |
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25 | exc_info = sys.exc_info() |
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26 | if (exc_info[0] != TypeError |
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27 | or str(exc_info[1]).find('arguments') == -1 |
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28 | or getattr(exc_info[1], '_type_error_fixed', False)): |
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29 | return exc_info |
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30 | exc_info[1]._type_error_fixed = True |
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31 | import inspect |
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32 | argspec = inspect.formatargspec(*inspect.getargspec(callable)) |
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33 | args = ', '.join(map(_short_repr, varargs)) |
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34 | if kwargs and args: |
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35 | args += ', ' |
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36 | if kwargs: |
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37 | kwargs = kwargs.items() |
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38 | kwargs.sort() |
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39 | args += ', '.join(['%s=...' % n for n, v in kwargs]) |
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40 | gotspec = '(%s)' % args |
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41 | msg = '%s; got %s, wanted %s' % (exc_info[1], gotspec, argspec) |
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42 | exc_info[1].args = (msg,) |
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43 | return exc_info |
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44 | |
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45 | def _short_repr(v): |
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46 | v = repr(v) |
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47 | if len(v) > 12: |
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48 | v = v[:8]+'...'+v[-4:] |
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49 | return v |
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50 | |
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51 | def fix_call(callable, *args, **kw): |
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52 | """ |
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53 | Call ``callable(*args, **kw)`` fixing any type errors that come |
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54 | out. |
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55 | """ |
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56 | try: |
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57 | val = callable(*args, **kw) |
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58 | except TypeError: |
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59 | exc_info = fix_type_error(None, callable, args, kw) |
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60 | raise exc_info[0], exc_info[1], exc_info[2] |
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61 | return val |
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