Added timings

pep-XXXX.rst

@@ -197,6 +197,40 @@ reintroducing redundant syntax.  On the other hand, Python already has
 multiple literals for strings with mostly the same behavior (single
 quoted, double quoted, single triple quoted, double triple quoted).
 
+Runtime Overhead of Wrappers
+============================
+
+I did some basic timings on the performance of a ``u()`` wrapper function
+as used by the `six` library.  The implementation of ``u()`` is as
+follows::
+
+    if sys.version_info >= (3, 0):
+        def u(value):
+            return value
+    else:
+        def u(value):
+            return unicode(value, 'unicode-escape')
+
+The intention is that ``u'foo'`` can be turned to ``u('foo')`` and that on
+Python 2.x an implicit decoding happens.  In this case the wrapper will
+have a decoding overhead for Python 2.x.  I did some basic timings to see
+how bad the performance loss would be.  The following examples measure the
+execution time over 10000 iterations::
+
+    u'\N{SNOWMAN}barbaz'            1000 loops, best of 3: 295 usec per loop
+    u('\N{SNOWMAN}barbaz')          10 loops, best of 3: 18.5 msec per loop
+    u'foobarbaz_%d' % x             100 loops, best of 3: 8.32 msec per loop
+    u('foobarbaz_%d') % x           10 loops, best of 3: 25.6 msec per loop
+    u'fööbarbaz'                    1000 loops, best of 3: 289 usec per loop
+    u('fööbarbaz')                  100 loops, best of 3: 15.1 msec per loop
+    u'foobarbaz'                    1000 loops, best of 3: 294 usec per loop
+    u('foobarbaz')                  100 loops, best of 3: 14.3 msec per loop
+
+The overhead of the wrapper function in Python 3 is the price of a
+function call since the function only has to return the argument
+unchanged.
+
+
 References
 ==========
 

timing.py

@@ -0,0 +1,86 @@
+# coding: utf-8
+import sys
+from subprocess import Popen
+
+
+ITERATIONS = 10000
+
+
+def u(value):
+    return unicode(value, 'unicode-escape')
+
+
+def bench_format_literal():
+    """u'foobarbaz_%d' % x"""
+    for x in xrange(ITERATIONS):
+        y = u'foobarbaz_%d' % x
+
+
+def bench_format_wrapped():
+    """u('foobarbaz_%d') % x"""
+    for x in xrange(ITERATIONS):
+        y = u('foobarbaz_%d') % x
+
+
+def bench_simple_literal():
+    """u'foobarbaz'"""
+    for x in xrange(ITERATIONS):
+        y = u'foobarbaz'
+
+
+def bench_simple_wrapped():
+    """u('foobarbaz')"""
+    for x in xrange(ITERATIONS):
+        y = u('foobarbaz')
+
+
+def bench_non_ascii_literal():
+    """u'fööbarbaz'"""
+    for x in xrange(ITERATIONS):
+        y = u'fööbarbaz'
+
+
+def bench_non_ascii_wrapped():
+    """u('fööbarbaz')"""
+    for x in xrange(ITERATIONS):
+        y = u('fööbarbaz')
+
+
+def bench_escaped_literal():
+    """u'\N{SNOWMAN}barbaz'"""
+    for x in xrange(ITERATIONS):
+        y = u'\N{SNOWMAN}barbaz'
+
+
+def bench_escaped_wrapped():
+    """u('\N{SNOWMAN}barbaz')"""
+    for x in xrange(ITERATIONS):
+        y = u('\N{SNOWMAN}barbaz')
+
+
+def list_benchmarks():
+    for name in sorted(globals().keys()):
+        if name.startswith('bench_'):
+            yield name[6:]
+
+
+def run_bench(name):
+    text = globals()['bench_' + name].__doc__.strip().decode('utf-8')
+    sys.stdout.write((u'%-32s' % text).encode('utf-8'))
+    sys.stdout.flush()
+    Popen([sys.executable, '-mtimeit', '-s',
+           'from timing import bench_%s as run' % name,
+           'run()']).wait()
+
+
+def main():
+    print '=' * 80
+    print 'Running benchmarks'
+    print '-' * 80
+    for bench in list_benchmarks():
+        run_bench(bench)
+    print '-' * 80
+
+
+if __name__ == '__main__':
+    main()