forked from mpusz/mp-units
refactor: quantity cration helpers are not opt-out rather than opt-in
Resolves #277
This commit is contained in:
Mateusz Pusz
+1
-1
@@ -6,7 +6,6 @@
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- (!) refactor: Refactored the library file tree
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- (!) refactor: `quantity::count()` renamed to `quantity::number()`
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- (!) refactor: `data` system renamed to `isq::iec80000` (quantity names renamed too)
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- (!) refactor: quantity UDLs support has to be enabled with `UNITS_LITERALS` preprocessor define
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- refactor: quantity (kind) point updated to reflect latest changes to `quantity`
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- refactor: basic concepts, `quantity` and `quantity_cast` refactored
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- refactor: `abs()` definition refactored to be more explicit about the return type
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@@ -17,6 +16,7 @@
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- feat: CTAD for dimensionless quantity added
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- feat: `modulation_rate` support added (thanks [@go2sh](https://github.com/go2sh))
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- feat: SI prefixes for `isq::iec80000` support added (thanks [@go2sh](https://github.com/go2sh))
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- feat: a possibility to disable quantity UDLs support with `UNITS_NO_LITERALS` preprocessor define
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- perf: preconditions check do not influence the runtime performance of a Release build
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- perf: `quantity_cast()` generates less assembly instructions
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- perf: temporary string creation removed from `quantity::op<<()`
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@@ -91,15 +91,3 @@ WARN_AS_ERROR = NO
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# The default value is: NO.
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QUIET = YES
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# The PREDEFINED tag can be used to specify one or more macro names that are
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# defined before the preprocessor is started (similar to the -D option of e.g.
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# gcc). The argument of the tag is a list of macros of the form: name or
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# name=definition (no spaces). If the definition and the "=" are omitted, "=1"
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# is assumed. To prevent a macro definition from being undefined via #undef or
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# recursively expanded use the := operator instead of the = operator.
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# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
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PREDEFINED = UNITS_REFERENCES \
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UNITS_LITERALS \
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UNITS_ALIASES
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@@ -70,7 +70,7 @@ Unit-Specific Aliases (Experimental)
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Additionally to the dimension-specific aliases there are also ones provided for
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each and every :term:`unit` in the library::
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#ifdef UNITS_ALIASES
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#ifndef UNITS_NO_ALIASES
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namespace units::aliases::isq::si::inline length {
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@@ -86,7 +86,7 @@ each and every :term:`unit` in the library::
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}
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#endif // UNITS_ALIASES
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#endif // UNITS_NO_ALIASES
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Using the above our code can look as follows::
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@@ -116,7 +116,7 @@ Quantity References (Experimental)
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Quantity References provide an alternative and simplified way to create quantities.
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They are defined using the `reference` class template::
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#ifdef UNITS_REFERENCES
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#ifndef UNITS_NO_REFERENCES
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namespace length_references {
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@@ -131,7 +131,7 @@ They are defined using the `reference` class template::
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} // namespace references
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#endif // UNITS_REFERENCES
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#endif // UNITS_NO_REFERENCES
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With the above our code can look as follows::
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@@ -157,7 +157,7 @@ User Defined Literals (Experimental)
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Alternatively, to construct quantities with compile-time known values the library provides
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:abbr:`UDL (User Defined Literal)` s for each :term:`unit` of every :term:`dimension`::
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#ifdef UNITS_LITERALS
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#ifndef UNITS_NO_LITERALS
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inline namespace literals {
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@@ -169,7 +169,7 @@ Alternatively, to construct quantities with compile-time known values the librar
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}
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#endif // UNITS_LITERALS
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#endif // UNITS_NO_LITERALS
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Thanks to them the same code can be as simple as::
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@@ -185,13 +185,6 @@ Thanks to them the same code can be as simple as::
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language (i.e. ``F`` (farad), ``J`` (joule), ``W`` (watt), ``K`` (kelvin),
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``d`` (day), ``l`` or ``L`` (litre), ``erg``, ``ergps``). This is why the
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``_q_`` prefix was consistently applied to all the UDLs.
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.. important::
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As one can read in the next section UDLs, are considered to be inferior to `Quantity References`_
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and their definition affects compile-time performance a lot. This is why they are an opt-in feature
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of the library and in order to use them one has to provide a `UNITS_LITERALS` preprocessor definition.
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UDLs vs Quantity References
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+++++++++++++++++++++++++++
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@@ -473,6 +466,19 @@ Summary
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+-----------------------------------------------+-------------+------------+---------------+
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Don't pay for what you don't use (compile-time performance)
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+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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As noted in the previous chapter, each quantity creation helper has a different impact on the compile-time
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performance. Aliases tend to be the fastest to compile but even their definition can be expensive for some
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if it is not used in the source code. This is why it is possible to opt-out from each or every quantity
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creation helper with the following preprocessor defines::
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#define UNITS_NO_ALIASES
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#define UNITS_NO_REFERENCES
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#define UNITS_NO_LITERALS
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Dimension-specific Concepts
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---------------------------
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@@ -3,8 +3,6 @@ Quick Start
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Here is a small example of possible operations::
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#define UNITS_REFERENCES
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#include <units/isq/si/area.h>
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#include <units/isq/si/frequency.h>
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#include <units/isq/si/length.h>
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@@ -34,7 +32,7 @@ Here is a small example of possible operations::
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.. admonition:: Try it on Compiler Explorer
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`Example #1 <https://godbolt.org/z/53bTahKd8>`_
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`Example #1 <https://godbolt.org/z/5dvY8Woh1>`_
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This library requires some C++20 features (concepts, classes as
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:abbr:`NTTP (Non-Type Template Parameter)`, ...). Thanks to them the user gets a powerful
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@@ -42,10 +40,6 @@ but still easy to use interface where all unit conversions and dimensional analy
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performed without sacrificing on accuracy. Please see the below example for a quick preview
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of basic library features::
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#define UNITS_ALIASES
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#define UNITS_LITERALS
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#define UNITS_REFERENCES
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#include <units/format.h>
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#include <units/isq/si/international/length.h>
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#include <units/isq/si/international/speed.h>
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@@ -92,7 +86,7 @@ of basic library features::
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.. admonition:: Try it on Compiler Explorer
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`Example #2 <https://godbolt.org/z/jKnPPPEx6>`_
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`Example #2 <https://godbolt.org/z/9fnzfbhb6>`_
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.. seealso::
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