November 6, 2025
Not a temp, just a vibe
A prvalue is not a temporary
C++ ‘ghost objects’ spark jargon wars while Rust fans gloat
TLDR: The post explains that prvalues are ideas, not real objects, so C++ avoids making extra copies unless needed. Comments erupted over dense jargon, confusion about old vs new behavior, and a Rust cameo claiming simplicity—making this a key update for anyone chasing performance without pain.
Today’s C++ blog bombshell says a “prvalue” isn’t a real object—more like the idea of an object—and only becomes one when absolutely necessary, cutting copies. Cue comment section chaos. One reader, dzdt, basically begged for subtitles, saying you need a decoder ring to even parse phrases like “move from.” Another chimed in with the classic: “Old habits die hard?” Wasn’t C++ always making “temporaries”? Not anymore (since newer standards), which has veterans nodding and newcomers clutching their keyboards.
Fans like Night_Thastus cheered that this is peak C++: do less copying whenever possible. But the crowd quickly split. On one side: “Please translate the jargon.” On the other: “This is how performance magic works.” Then came the language war cameo: steveklabnik rolled in with a Rust comparison, claiming Rust’s model is simpler—two categories vs C++’s alphabet soup—promptly triggering a mini flame thread.
The vibes got confessional too: p0w3n3d shared exam trauma and a “learn C first” survival arc, sparking jokes that C++ has “boss-level unlocks.” The meme of the day? “Schrödinger’s vector”—not a temp, just a vibe—until a reference forces it to materialize. Whether you love the speed or hate the syntax, the takeaway is clear: fewer copies, more brain knots, and a fresh round of Rust vs C++ cage matches.
Key Points
- •A prvalue is not inherently a temporary; it represents an object idea and materializes only when necessary.
- •lvalues refer to existing objects and cannot be moved from, while rvalues can be moved from.
- •std::move converts an lvalue into an rvalue (xvalue), allowing moves from existing objects.
- •Prvalues can directly initialize variables or by-value parameters without creating extra temporaries or performing copies/moves.
- •Binding a prvalue to a reference parameter triggers temporary materialization; return-by-value calls are prvalues that directly initialize targets.