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Don't use argument unpacking on strings#57
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eric-wieser wants to merge 2 commits intoros:indigo-develfrom
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Don't use argument unpacking on strings#57eric-wieser wants to merge 2 commits intoros:indigo-develfrom
eric-wieser wants to merge 2 commits intoros:indigo-develfrom
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Ouch! In [1]: import struct
In [2]: data = b" "*100000
In [3]: % timeit struct.pack('100000s',data) # with this patch
The slowest run took 4.30 times longer than the fastest. This could mean that an intermediate result is being cached
100000 loops, best of 3: 15.3 µs per loop
In [4]: % timeit struct.pack('100000B',*data) # without it
100 loops, best of 3: 7.48 ms per loop |
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And at the extreme: In[1]: import struct
In[2]: data = b" " * 1000000000
In[3]: %timeit struct.pack('s', data)
The slowest run took 7.66 times longer than the fastest. This could mean that an intermediate result is being cached
1000000 loops, best of 3: 487 ns per loop
In[4]: %timeit struct.pack('B', *data)
MemoryError |
test/test_genpy_generator.py
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| assert "chr(0)*1" == default_value(msg_context, 'uint8[1]', 'roslib') | ||
| assert "chr(0)*4" == default_value(msg_context, 'uint8[4]', 'roslib') | ||
| assert b'\0' == eval(default_value(msg_context, 'uint8[1]', 'roslib') |
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Invalid syntax: lacks trailing ).
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Thanks! I had no idea why the marker was pointing at the start of the line in the traceback
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I think it would make a lot more sense for every assertion in this test of be of the form |
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These tests now fail because the python output of the generator has changed. At some point I'll update the expected output files to match the new output |
`struct.pack('5s', b'abcde')` works just fine for me on 3.5.0
And so `chr` is also not safe. `b'\0' works fine in both versions.
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Thank you for the patch. Merged to kinetic-devel in #63. |
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struct.pack('5s', b'abcde')works just fine for me on 3.5.0. Argument unpacking a string is going to be a big performance hit for long strings too