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bool.md

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Definition of Bool

Problem

Inconsistent use of bool in various parts of Elektra.

Constraints

Assumptions

  • needs to be string
  • convenience plugins can convert anything to 0 or 1
  • type checker plugins can reject everything not 0 or 1

Considered Alternatives

  • strictly only allow 0 and 1 (would move validation across the code)
  • only check presence or absence (no cascading override of already present key possible)
  • use as in CMake (would move convenience across the code)

Decision

Use, depending on what your default should be:

  • 0 is false, everything else is true (default is true)
  • 1 is true, everything else is false (default is false)

Example:

if ( strcmp(keyString(k), "0")) {/*true*/} else {/*false*/}
if (!strcmp(keyString(k), "1")) {/*true*/} else {/*false*/}

In the documentation it should mention that a bool is used and which is the default.

The type checker plugin should allow

  • non-presence (default)
  • the string "0"
  • the string "1"

The convenience plugin should transform (it might be combined with a plugin that transforms everything lower-case):

  • "false", "off", "no" to "0"
  • "true", "on", "yes" to "1"

Rationale

  • most easy to implement
  • allows presence to be true
  • plugins allow us to convert to any other behavior

Implications

  • change code with different behavior

Related Decisions

Notes

See here