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4105 :: strformat using a run-time defined format string

• woggy (orginal) [2018-08-05T10:31:55+02:00] view original

  In Python I can do something like this

  f = "{:6e}"
  print(f.format(5))  # '5.000000e+00'
  Run

  I can't figure out how to do something like this in Nim. As far as I can tell this is not possible using strformat. Can someone point me in the right direction?

  Thanks.

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• mratsim (orginal) [2018-08-05T11:18:38+02:00] view original

  strformat is using compile-time macro.

  For runtime have a look at formatFloat and formatBiggestFloat in strutils

  General tips: you can use theindex if you are tracking down proc from the standard library.

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• dom96 (orginal) [2018-08-05T13:54:50+02:00] view original

  To elaborate a bit on @mratsim's answer: you cannot change the format pattern string at runtime. But perhaps that isn't what you are trying to do, in any case the docs actually have some good examples: https://nim-lang.org/docs/strformat.html#formatting-floats

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• jyapayne (orginal) [2018-08-05T14:14:21+02:00] view original

  @woggy, you could also try a library like this one: https://github.com/kaushalmodi/strfmt

  Looking at the docs, it does support runtime evaluation.

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• woggy (orginal) [2018-08-06T05:31:36+02:00] view original

  Thanks peeps.

  What I really wanted is the format function in the strfmt library mentioned above. I went with formatFloat for now as it does what I want and is available in the standard library. The compile time fmt strings are fantastic but I hope in the future something like format will also be in the standard library.

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