Whitespaces are a Production Risk

Production RiskSoftware ResiliencyProgramming Best Practices

Whitespaces are a Production Risk

Count one violation each time a format replacement field contains a whitespace.


print "{ what} is {how it is}".format({"what": "life", "how it is": "hard"})
# Output: KeyError; the correct key would be ' what' with a leading whitespace

print "{ what} is {how it is}".format({" what": "life", "how it is": "hard"})
# Output: KeyError; notice the double whitespace in the placeholder


print "{what} is {how_it_is}".format({"what": "life", "how_it_is": "so much easier if you use QuantifiedCode"})
# Output: "life is so much easier if you use QuantifiedCode"


Why you should care

If you use a replacement field like { var} in your format string, which contains a whitespace in its name, the key of the corresponding entry in your dictionary must contain this whitespace, too. Since whitespaces are easy to miss and you should avoid them.

Business Impacts

Production Risk

CAST recommendations




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