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Standards Wording Idioms
sdutoit edited this page Nov 7, 2011
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This is a list of some common idioms in the standard that should be used to specify certain cases, and corresponding anti-idioms that should not be used.
When you are writing proposals for changes to the C++ standard, please try to follow these idioms. If you notice an anti-idiom in the current C++ standards draft, please [submit an editorial issue](How to submit an editorial issue).
| Case | Idiom(s) | Anti-idiom(s) | Example |
|---|---|---|---|
|
Normative
requirement Use this idiom when specifying something we require a conforming implementation to do. |
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"Unless it is a bit-field, a most derived object shall have a non-zero size" |
|
Normative encouragement Use this idiom when specifying something we would prefer, but do not require, implementations to do. |
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"Implementations should ensure that all unblocked threads eventually make progress" |
|
Complicated conditional
cases Use this idiom when you are enumerating a set of possibilities, and stating requirements under those possibilities. |
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"If E1 is an lvalue, then E1.E2 is an lvalue; if E1 is an xvalue, then E1.E2 is an xvalue; otherwise, it is a prvalue." |
- Variations on "ill-formed"