Magic Numbers are a Production Risk

Production RiskSoftware ResiliencyProgramming Best Practices

Magic Numbers are a Production Risk

This code insight counts one violation each time a litteral numeric constant is encountered, that is not assigned to a constant.

  • interger : (0|0[xX])?[0123456789ABCDEF]+([lL]?
  • decimal : ([0-9]*\.[0-9]+|[0-9]+\.)
  • real : [0-9]+[eE][+-]?[0-9]+


  • one digit integer
  • 0.0, .0, 0.
  • 1.0

Note : a constant is a variable assigned only one time in its scope.


PI = 3.14          # not a violation because assigned to a constant
CONST = 123 * 456  # 2 violations : the assignation is an expression (containing 2 Magics)
a = 12             # violation because assigned to a variable
if (b):
    a = b



Why you should care

It is recommended to use constants as default values for arguments in a function or method. This is cleaner, easier to read and there’s only one place to modify. Make sure, you document your constant, to explain where the value comes from.

Highlight :

Avoid litteral numeric constants.

Business Impacts

Production Risk

CAST recommendations



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