## +24 ## Designing a Slimmer Vector of Variants ## CHRISTOPHER FRETZ ## Designing a Slimmer Vector of Variants Engineering CppCon 2024 September 18, 2024 Chris Fretz Senior C++ Engineer TechAtBloomberg code - Original motivating use-case was modeling a time series of market events as a vector of variants, where one of the types in the variant happened to be 10x larger than the rest. TechAtBloomberg operator [] - This is extremely unfortunate, but is an inevitable outcome of not actually storing variants inside the vector • Could theoretically work around this by returning a proxy class, but this seems

84.4.5 LocalToEpoch ..... 2105 84.4.6 StringToPPChar ..... 2105 5 Reference for unit 'Variants' ..... 2107 85.1 Used units ..... 2107 85.2 Overview ..... 2107 85.3 Constants, types pointer, so 32-bit on 32-bit platforms, 64-bit on 64-bit platforms. It is advisable to use unsigned variants of this type. See PtrUInt (1375) for details. NativeUInt = PtrUInt NativeUInt is defined for Delphi information for the current OS. This structure is OS dependent. TError = LongInt Error type, used in variants. TErrorProc = procedure(ErrNo: LongInt; Address: CodePointer; Frame: Pointer) Standard error handler

multiple languages at the same URL, HTTP's caching mechanism makes it possible to cache multiple variants of the same page at the same URL. This is done by the origin server adding a Vary header to indicate indicate which headers must be taken into account by a cache when determining whether two variants are different from one another. If for example, a response is received with a vary header such as; Vary: Multiple variants of the content can be cached side by side, mod cache uses the Vary header and the corresponding values of the request headers listed by Vary to decide on which of many variants to return

multiple languages at the same URL, HTTP's caching mechanism makes it possible to cache multiple variants of the same page at the same URL. This is done by the origin server adding a Vary header to indicate indicate which headers must be taken into account by a cache when determining whether two variants are different from one another. If for example, a response is received with a vary header such as; Vary: Multiple variants of the content can be cached side by side, mod cache uses the Vary header and the corresponding values of the request headers listed by Vary to decide on which of many variants to return

multiple languages at the same URL, HTTP's caching mechanism makes it possible to cache multiple variants of the same page at the same URL. This is done by the origin server adding a Vary header to indicate indicate which headers must be taken into account by a cache when determining whether two variants are different from one another. If for example, a response is received with a vary header such as; Vary: Multiple variants of the content can be cached side by side, mod cache uses the Vary header and the corresponding values of the request headers listed by Vary to decide on which of many variants to return

materials … 139 Generating a Netlist … 144 Design variants … 152 Understanding design variants … 152 Types of variation … 152 Creating and managing variants … 153 Editing variant data … 155 Generating variant-aware variant-aware outputs … 156 Command-line variant support … 156 Text variables … 157 Transferring variants to the PCB editor … 157 Symbols and Symbol Libraries … 158 Managing symbol libraries … 158 Browsing Net-R1-Pad2 1k V1 Net-R1-Pad2 GND AC 1 V2 VDD GND DC 10 V3 GND VSS DC 10 .ac dec 10 1 1Meg .end Design variants Many products share a common circuit board but are sold in different configurations. A consumer

types such as Iterable without first importing them. Note: In some examples we use capitalized variants of types, such as List, and sometimes we use plain list. They are equivalent, but the prior variant need to elide actual logic in regular Python code – for example, when writing methods in overload variants or custom protocols. The recommended style is to use ellipses to do so, just like in stub files function's behavior: from typing import Union, overload # Overload *variants* for 'mouse_event'. # These variants give extra information to the type checker. # They are ignored at runtime

types such as Iterable without first importing them. Note: In some examples we use capitalized variants of types, such as List, and sometimes we use plain list. They are equivalent, but the prior variant need to elide actual logic in regular Python code – for example, when writing methods in overload variants or custom protocols. The recommended style is to use ellipses to do so, just like in stub files function's behavior: from typing import Union, overload # Overload *variants* for 'mouse_event'. # These variants give extra information to the type checker. # They are ignored at runtime

a fixed set of values, and those values are called the enum’s variants. Chapter 6 will cover enums in more detail. For Result, the variants are Ok or Err. Ok indicates the operation was successful, and :cmp::Ordering into scope from the standard library. Ordering is another enum, like Result, but the variants for Ordering are Less, Greater, and Equal. These are the three outcomes that are possible when you handling the error. Remember that parse returns a Result type, and Result is an enum that has the variants Ok or Err. We’re using a match expression here, like we did with the Ordering result of the cmp

html#typing.Iterable] without first importing them. ## Note In some examples we use capitalized variants of types, such as List, and sometimes we use plain list. They are equivalent, but the prior variant need to elide actual logic in regular Python code – for example, when writing methods in overload variants or custom protocols. The recommended style is to use ellipses to do so, just like in stub files the function’s behavior: from typing import Union, overload # Overload *variants* for 'mouse_event'. # These variants give extra information to the type checker. # They are ignored at runtime