A C++14-compatible physical units library with no dependencies and a single-file delivery option. Emphasis on safety, accessibility, performance, and developer experience.
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Add labels for integer and rational magnitudes #331
Think of this as "just enough of #85 to unblock #105". The fact that
our common unit labels don't tell you the size of the unit (#105) has
really, really been bugging me for a long time. Recently, I realized we
don't need to do all of #85 to get it! Instead, all we need to do is:
Build a mechanism that we can easily extend.
Cover the most important use cases.
This PR creates the MagnitudeLabel trait mechanism (also accessible
via a function/value interface as mag_label). We enumerate the
various categories of magnitudes that we can label, defaulting to
"unsupported". The first two supported categories are integers (that
fit in std::uintmax_t), and rationals.
We also add a trait, has_exposed_slash, looking forward to the obvious
use case of auto-generating labels for scaled units. Those labels will
have the form "[M U]" for a unit of label "U" scaled by a magnitude
of label "M". If has_exposed_slash is true for a given magnitude
label, then we'll know to make this "[(M) U]" instead.
Finally, we move a couple of StringConstant-ish utilities into
"string_constant.hh", so that we can use them in our implementation.
Think of this as "just enough of #85 to unblock #105". The fact that our common unit labels don't tell you the size of the unit (#105) has really, really been bugging me for a long time. Recently, I realized we don't need to do all of #85 to get it! Instead, all we need to do is:
Build a mechanism that we can easily extend.
Cover the most important use cases.
This PR creates the
MagnitudeLabeltrait mechanism (also accessible via a function/value interface asmag_label). We enumerate the various categories of magnitudes that we can label, defaulting to "unsupported". The first two supported categories are integers (that fit instd::uintmax_t), and rationals.We also add a trait,
has_exposed_slash, looking forward to the obvious use case of auto-generating labels for scaled units. Those labels will have the form"[M U]"for a unit of label"U"scaled by a magnitude of label"M". Ifhas_exposed_slashistruefor a given magnitude label, then we'll know to make this"[(M) U]"instead.Finally, we move a couple of
StringConstant-ish utilities into"string_constant.hh", so that we can use them in our implementation.Helps #85.