Chapter 10: Implementing Subprograms

Actions performed by a called subprogram when it's finished executing. It includes parameter value transferring, potentially copying the function result, restoring the caller's execution state and control transfer.

A set of dynamic links in a stack at a particular moment. This chain allows tracing the call hierarchy of active subprograms.

The distance, measured in terms of memory locations, between a local variable and the beginning of the associated activation record. (Activation record is an area in memory used for a subprogram call.)

A block of memory allocated during a subprogram call. It contains information including local variables and the dynamic link.

A parameter passing method where a value is passed from the caller to the callee, then the callee modifies that value, and the modified value is passed back to the caller.

The combined processes of calling and returning a subprogram, including parameter passing, local variable allocation, execution status management, control transfer, and return.

The actions performed when a subprogram is called, involving saving the caller's execution status, passing parameters, and transferring control to the called subprogram.

The actions performed when a subprogram finishes executing, including transferring modified parameter values, returning the function result, restoring the caller's execution status, and transferring control back to the caller.

Memory space allocated for storing information related to a subprogram call, including execution status, parameters, return address, return value (for functions), and temporary variables.

Local variables that are allocated storage space on the runtime stack when the subprogram is called, and their storage is deallocated when the subprogram returns.

Subprograms defined within other subprograms, allowing for hierarchical organization and data encapsulation.

Code segments within a program where variables and statements are grouped together, providing local variable scoping and control flow.

A scoping rule where the scope of a variable is determined at runtime based on the dynamic call chain, allowing access to variables from enclosing subprograms.

A concrete manifestation of an Activation Record, representing the specific data associated with a particular invocation of a subprogram.

A pointer within an activation record that points to the activation record of the calling subprogram.

A pointer that always points to the base of the current subprogram's activation record.

Actions performed by a called subprogram at the beginning of its execution, including saving the caller's state and allocating local variables.

Actions performed by a called subprogram at the end of its execution, including restoring the caller's state and returning control.

A parameter passing method where a copy of the actual parameter is passed to the called subprogram, modifications are made to the copy, and the modified copy is passed back to the caller.

The process of starting a subprogram's execution. This involves saving the caller's state, passing arguments, and transferring control to the subprogram.

The process of finishing a subprogram's execution and resuming the caller's execution. This involves transferring back any modified values and restoring the caller's state.

The mechanism of transferring data from the caller to the subprogram and potentially back to the caller. Different methods exist, like 'pass-by-value' and 'pass-by-reference'.

A parameter passing method where the caller's parameter value is copied into a new memory location for the subprogram to use. Any changes made to the subprogram's copy do not affect the original value.

A parameter passing method where the caller's parameter location in memory is shared with the subprogram. Any changes made to the subprogram's version also affect the original value.

A value that a subprogram can send back to its caller. This value can be used for various purposes, such as conveying the result of a calculation or a status code indicating success or failure.

Subprograms offer several advantages, including improved code organization, reusability, easier debugging, and abstraction.

A block of code designed to perform a specific task, which can be called and reused multiple times.

The steps involved in starting a subprogram: saving the caller's state, passing parameters, and transferring control to the subprogram.

The steps involved in ending a subprogram: transferring modified values, returning the result, restoring the caller's state, and transferring control back.

A parameter passing method where the caller's value is copied for the subprogram, and any changes to the copy don't affect the original value.

A parameter passing method where the subprogram directly accesses the caller's original memory location, and any changes affect the original value.

The ability of a subprogram to call itself, allowing it to repeatedly break down complex problems into simpler ones.

The stack manages activation records for recursive calls. Each call has its own record, allowing for proper state restoration when returning.

A data structure that grows and shrinks as functions are called and return, managing activation records and ensuring proper memory allocation.

A programming technique where a subprogram calls itself, allowing for the breakdown of complex problems into simpler, repeated subproblems.

The process of allocating and deallocating memory for variables and subprograms, ensuring efficient use and preventing errors like stack overflow.

A chain of links connecting activation records of nested functions, enabling inner functions to access variables declared in their enclosing functions.

Variables declared in an enclosing function that can be accessed by nested subprograms within that function.

Functions that retain access to variables from their surrounding environment, even after the enclosing function has finished execution.

By using the static chain, which connects activation records of nested functions, allowing inner functions to find the variables declared in their enclosing functions.

The static chain enables inner functions to access non-local variables by providing a path to the activation records of their enclosing functions.

Each activation record includes a static link that points to the activation record of the enclosing function. This creates a chain of links that allows nested functions to access variables in their enclosing scopes.

Nested subprograms provide data encapsulation by limiting the scope of helper functions to the enclosing function, they are crucial for creating closures, and they can be used for implementing stateful components.

Variables in an outer function can be accessed by inner nested functions, forming a static scope.

The lifetime of a non-local variable depends on its enclosing function's lifetime, while its visibility is determined by the static nesting structure.

Creating closures in JavaScript or Python, implementing mathematical functions with intermediate calculations, managing state in UI components.

Code segments within a program that have their own local scope, meaning variables declared inside them are only accessible within the block.

They store temporary variables used within a block, ensuring they only exist while the block is executing.

By limiting the lifetime of variables to the scope of the block, resources can be released more effectively.

Python uses blocks with the with statement, allowing programmers to manage resources like files or network connections, ensuring they are properly closed.

A block can be used to declare a temporary variable to hold the value of one array element while the other elements are swapped.

A block is a code segment within a function that encloses a set of statements and variables, creating a separate local scope. Variables declared inside a block are only accessible within that block.

Blocks help manage memory by limiting the lifetime of variables to the block's scope. They ensure that variables and resources are only allocated when needed and deallocated when the block exits.

An activation record is created for each block. This record stores local variables declared within that block, ensuring their values are only accessible within that block.

In C, a block is defined using curly braces {}. For example, { int b = 5; } would create a block with a local variable b that can only be accessed within the block's scope.

Python's with statement uses blocks to manage resources, such as files and network connections. This guarantees that the resources will be closed automatically when the block exits.

A technique for implementing dynamic scoping where non-local variable lookups are done using a central table, making access fast but requiring careful management to avoid conflicts.

An approach to dynamic scoping where non-local variables are located by traversing the call chain, making it slower for deeply nested calls.

Variable visibility depends on the order in which functions are called, allowing more flexible access but potentially introducing unintended side effects.

Dynamic scoping is useful in scripting languages like Lisp, configuration management, and feature toggling, where flexibility in accessing and modifying variables is crucial.