33 lines
708 B
Python
33 lines
708 B
Python
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#!/usr/bin/python3
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"""
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Input/Output utilities.
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"""
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import sys
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def readvalue(msg, type_, emsg=None, fin=sys.stdin, fout=sys.stdout):
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"""
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Basically uses ``input(msg)`` until it has been able to convert
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the input to ``type_``. Prints the error message ``emsg``
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if supplied, else the type error message.
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Reads from ``fin`` and writes to ``fout``. They default to ``sys.stdin``
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and ``sys.stdout``.
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"""
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x = None
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while(x is None):
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print(msg, file=fout, flush=True, end="")
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x_raw = fin.readline()
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try:
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# Remove the trailing \n.
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x = type_(x_raw[:-1])
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except ValueError as e:
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if(emsg):
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print(emsg, file=fout, flush=True)
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else:
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print(str(e), file=fout, flush=True)
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return x
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