Call by value
Call by value is a parameter-passing semantics in which a called operation receives its own copy of an argument’s value.
Object-Oriented Software Design in C++
A parameter-passing mechanism that initializes a function parameter with a copy of the argument value.
- How it is used
- Uses parameter passing to expose hidden copies and explain poor performance in vector-based C++ code.
- How deep it goes
- Traces copy construction, vector growth, allocation, and destruction, then stops short of a complete alternative design.
- Examples
- Demonstrates Date arguments passed to append and Appointments passed to print, using instrumented lifecycle output.
- What you can do after
- Diagnose performance problems by identifying unexpected copies, allocations, and destructions in instrumented C++ programs.
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Go by Example
Pass-by-value is a parameter-passing semantics in which a function receives a copy of each argument's value.
- How it is used
- Uses copied Result values to process synchronous API results without unnecessary shared state.
- How deep it goes
- Explains value-versus-pointer semantics, mutation, goroutine isolation, allocation, stack use, caching, and garbage-collector trade-offs.
- Examples
- Uses Result, Send, SendN, yield, Results, and Summarize to demonstrate copied values in a result-processing pipeline.
- What you can do after
- Evaluate whether functions should receive Result values or pointers based on mutation, isolation, allocation, and garbage-collection concerns.
100 Go Mistakes and How to Avoid Them
A value copy is an independent value produced by copying another value rather than referring to the original value.
- How it is used
- Diagnoses failed mutations in Go range loops and guides the choice between value, index, and pointer access.
- How deep it goes
- Explains struct and pointer copying, then stops at practical slice-update patterns rather than language-runtime internals.
- Examples
- Uses account balances to contrast ineffective value-variable mutation with indexed and pointer-based updates.
- What you can do after
- Apply value-copy rules to choose a loop form that predictably mutates or preserves slice elements.
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Related concepts
- range loopproduced by · A range loop is a Go for-loop form that iterates over values or entries produced by a supported rangeable expression.
- structused by · A struct is a composite data type or structure that groups related fields or values into a single unit.
- array parametercontrasts with · An array parameter is a C function parameter declared with array syntax that is adjusted to a pointer to its element type.
- function argumentuses · A function argument is a value or expression supplied when a function or method is invoked, providing input to the called operation.
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