Initial Util Package

Makefile

@@ -0,0 +1,6 @@
+
+.PHONY: test
+
+test:
+	python3 -m pytest test/
+

test/test_io.py

@@ -0,0 +1,41 @@
+from io import StringIO
+from util.io import readvalue
+
+def test_io_readvalue_int():
+	fin = StringIO("10\n")
+	fout = StringIO()
+
+	result = readvalue("Enter an Integer ", int, fin=fin, fout=fout)
+
+	assert result == 10
+
+def test_io_readvalue_msg():
+	fin = StringIO("10\n")
+	fout = StringIO()
+	readvalue("Enter an Integer ", int, fin=fin, fout=fout)
+	fout.seek(0, 0)
+
+	result = fout.read()
+
+	assert result == "Enter an Integer "
+
+def test_io_readvalue_float():
+	fin = StringIO("10.1\n")
+	fout = StringIO()
+
+	result = readvalue("Enter a Float ", float, fin=fin, fout=fout)
+
+	assert result == 10.1
+
+def test_io_readvalue_int_fail():
+	fin = StringIO("10.1\n10\n")
+	fout = StringIO()
+	readvalue("Enter an Integer ", int, fin=fin, fout=fout)
+	fout.seek(0, 0)
+
+	result = fout.read()
+
+	assert result == ("Enter an Integer " 
+			r"invalid literal for int() with base 10: '10.1'"
+			"\nEnter an Integer ")
+

util/io.py

@@ -0,0 +1,32 @@
+#!/usr/bin/python3
+
+"""
+Input/Output utilities.
+"""
+
+import sys
+
+
+def readvalue(msg, type_, emsg=None, fin=sys.stdin, fout=sys.stdout):
+	"""
+	Basically uses ``input(msg)`` until it has been able to convert 
+	the input to ``type_``. Prints the error message ``emsg``
+	if supplied, else the type error message.
+
+	Reads from ``fin`` and writes to ``fout``. They default to ``sys.stdin``
+	and ``sys.stdout``.
+	"""
+	x = None
+	while(x is None):
+		print(msg, file=fout, flush=True, end="")
+		x_raw = fin.readline()
+		try:
+			# Remove the trailing \n.
+			x = type_(x_raw[:-1])
+		except ValueError as e:
+			if(emsg):
+				print(emsg, file=fout, flush=True)
+			else:
+				print(str(e), file=fout, flush=True)
+
+	return x